AP Biology - Ecology Summer Notes PDF

Ecology Summer Notes By: Arush Gupta Teacher: Period: KEY: j YELLOW - Definitions and key terms GREEN - Examples BLUE - Photos with reference letters PINK - Main idea/summary of the lesson Chapter 34 (sections 1-...

Ecology Summer Notes By: Arush Gupta Teacher: Period: KEY: j YELLOW - Definitions and key terms GREEN - Examples BLUE - Photos with reference letters PINK - Main idea/summary of the lesson Chapter 34 (sections 1-5 only) Chapter 35 (all sections) Chapter 36 (sections 1-8 only) Chapter 37 (all sections) Chapter 38 (sections 1-6 only) 34.1 - Ecologists study how organisms interact with their environment at several levels Ecology - The study of interactions between organisms and their environment Variables/Factors that affect organisms: photo (a) ○ Biotic Factors - The living components of the environment Examples: Bacteria, fungi, protists, plants, animals ○ Abiotic Factors - The non-living components of the environment Examples: Temperature, water, nutrients Habitat - The place/environment in which an organism lives in Levels of Organization/Study: photo (b) ○ Organism - Studying one organism and its behaviors in an environment Examples: Adaptations of the blue poppy to temperature in its environment ○ Population - Groups of individuals of the same species in a particular area Examples: How nutrient availability affects the size of the blue poppy population ○ Community - All populations in an area (all the biotic factors) Examples: Impact of plant-eaters on poppies OR poppies interacting with other plants ○ Ecosystem - All the biotic and abiotic factors in an ecosystem Examples: How chemicals cycle and how energy flows within an ecosystem ○ Biosphere - All areas of Earth that support life Landscape - Many different ecosystems connected with exchanges of energy, materials, and organisms (a) (b) 34.2 - The science of ecology provides insight into environmental problems The study of DDT shed light on problems with chemicals interacting with the environment ○ DDT is a chemical pesticide (used against crop pests and disease-carrying insects, like mosquitos and fleas) ○ It was determined that DDT had negative consequences on the environment and organisms living in it (particularly the bird populations whose shells were weakened by an accumulation of DDT in their fatty tissues) ○ DDT remains in the soil long after its application Rachel Carson wrote a famous book called Silent Spring, published in 1962, which brought attention to these concerns and raised public awareness. This led to new laws in the 1970’s aimed towards curbing pollution and cleaning up the environment 34.3 - Physical and chemical factors influence life in the biosphere Energy Sources ○ Energy is required for all living things ○ Solar energy from sunlight powers most ecosystems, influencing competition and location for aquatic photosynthesis ○ In dark environments where sunlight isn’t available, inorganic chemicals are used instead of light Temperature ○ There is a narrow temperature range in which organisms can thrive ○ Mammals and birds can exist in a wider range of temperatures than amphibians and reptiles, which factors into where they can be distributed ○ Few organisms can maintain a sufficiently active metabolism at temperatures close to 0°C, and temperatures above 45°C (113°F) destroy the enzymes of most organisms Water ○ Water is essential to all organisms ○ Dehydration needs to be avoided, so many organisms have adaptations to help regulate their water balance Inorganic Nutrients ○ Nitrogen and phosphorus are important inorganic nutrients  ○ The amount of available N and P determines where plants, algae and bacteria can live Other Aquatic Factors ○ Dissolved oxygen, salinity, currents and tides are factors that affect only aquatic organisms (not terrestrial) Other Terrestrial Factors ○ Wind is an important terrestrial factor because it can increase water loss Major factors include energy sources, temperature, the presence of water, and inorganic nutrients 34.4 - Organisms are adapted to abiotic and biotic factors through natural selection Examples through the Pronghorn ○ “The biotic environment, which includes what the animal eats and any predators that threaten it, is also a factor in determining which members of a population survive and reproduce” ○ Pronghorn’s mainly eat small broadleaf plants, grasses, and woody shrubs, so their teeth has evolved to be specialized for biting/chewing tough plant material ○ The Pronghorn has evolved to be the fastest mammal on the continent and run at a top speed of 60mph to escape the wolf, its main predator, so it can survive ○ The Pronghorn has also evolved to survive while living in herds, and keep a tan and white coat, which provides camouflage. It also has keen eyes, which can detect movement at great distances, and once one Pronghorn runs due to danger, the entire pack does the same, being alerted by the white rump patch ○ “Thus, the adaptations shaped by natural selection in the distant past still serve as protection from the predators of today’s environment” The pronghorn’s adaptations show the variety of factors that can affect an organism’s fitness 34.5 - Regional climate influences the distribution of terrestrial communities Earth receives an uneven distribution of solar energy, as shown in photo (c), leaving areas of water/land near the equator to absorb more heat than anywhere else around the world  Tropics - The region surrounding the equator between latitudes 23.5° north (the Tropic of Cancer) and 23.5° south (the Tropic of Capricorn) Temperature Zones - Latitudes between the tropics and the Arctic Circle in the north, and the Antarctic Circle in the south; region with milder climates than the tropics or polar regions Photo (d) shows how the intense sunlight near the equator affects global patterns of rainfall and winds. Arrows indicate air movements. The tropic’s high temperatures evaporate water from Earth’s surface and cause warm/moist air masses to rise and flow toward the poles. As rising air cools, its ability to hold moisture lowers. The water vapor condenses into clouds and rain falls.High temperatures throughout the year and ample rainfall largely explain why rain forests are concentrated near the equator Prevailing Winds - Major global air movements; winds that result from the combined effects of Earth’s rotation and the rising and falling of air masses ○ Trade Winds flow from east to west; located in the tropics ○ Westerlies flow from west to east; located in the temperature zones Ocean Currents - Combination of prevailing winds, the planet’s rotation, unequal heating of surface waters, and the locations/shapes of the continents; ­river-like flow patterns at the oceans’ surface Ocean currents have a profound effect on regional climates. Landforms can also affect local climate. Climate and other abiotic factors of the environment control the global distribution of organisms Biomes - Major types of ecological associations that occupy broad geographic regions of land or water and is characterized by organisms adapted to the particular environment Most climatic variations are due to the uneven heating of Earth’s surface as it orbits the sun, setting up patterns of precipitation and prevailing winds. Ocean currents influence coastal climate. Landforms such as mountains affect rainfall (d) (c) 35.1 - Proximate and ultimate factors cause behavior Behavior - An action carried out by muscles or glands under the control of the nervous system in response to an environmental cue ○ Behavioral ecology - Study of behavior in an evolutionary context. Proximate Questions - In animal behavior, a question that concerns the immediate reason for a behavior; how is it triggered by stimuli ○ Stimuli - (1) In the context of a nervous system, any factor that causes a nerve signal to be generated. (2) In behavioral ecology, an environmental cue that triggers a specific response Example: Researchers studying the mating pattern of prairie voles might ask, “How do voles choose their mates?” or “How does the act of mating cause voles to form lifelong bonds with their partners?” Proximate Cause - In animal behavior, a condition in an animal’s internal or external environment that is the immediate reason or mechanism for a behavior Ultimate Question - In animal behavior, a question that addresses the evolutionary basis for behavior Ultimate Cause - In animal behavior, the evolutionary reason for a behavior Behavioral ecology is the study of behavior in an evolutionary context, considering both proximate (immediate) and ultimate (evolutionary) causes of an animal’s actions. Natural selection preserves behaviors that enhance fitness 35.2 - Fixed action patterns are innate behaviors Innate Behavior - Behavior that is under strong genetic control and does not have to be learned Fixed Action Patterns (FAPs) - A genetically programmed, predictable behavioral sequence performed in response to a certain stimulus ○ Example: Coffee Machine. A person feeds money into the machine and presses a button. Having received this stimulus, the machine performs a series of actions: drops a cup into place; releases a specific volume of coffee; adds cream; adds sugar. Once the stimulus—in this case, the money—triggers the mechanism, it carries out its complete program. Likewise, FAPs are behavioral routines that are completed in full Humans perform FAPs, too  The proximate cause of a FAP is often a simple environmental cue. The ultimate cause is that natural selection favors behaviors that enable animals to perform tasks essential to survival without any previous experience Innate behavior is performed a similar way by all members of a species. A fixed action pattern (FAP) is a predictable series of actions triggered by a specific stimulus. FAPs ensure that activities essential to survival are performed correctly without practice 35.3 - Both genetics and environment influence behavior Genetic engineering has been used to investigate genes that influence behavior. Cross-fostering experiments are useful for studying environmental factors that affect behavior 35.4 - Habituation is a simple type of learning Learning - modification of behavior as a result of specific experiences ○ There are many types of learning, check photo (e) Learning is a change in behavior resulting from experience. Habituation is learning to ignore a repeated, unimportant stimulus (e) Example of Habituation: Your friend hums while studying. You …….. found this habit extremely annoying at iiii… first, but after a while you stopped ……… noticing it. 35.5 - Imprinting requires both innate behavior and experience Imprinting - Learning that is limited to a specific time period in an animal’s life and that is generally irreversible Sensitive Period - A limited phase in an individual animal’s development when learning of particular behaviors can take place Example of both the above: When an incubator-hatched bird spends its first few hours with a human, it behaves as if the human is its mother Imprinting is irreversible learning limited to a sensitive period in the animal’s life 35.6 - Imprinting poses problems and opportunities for conservation programs In attempting to save species that are at the edge of extinction, biologists sometimes try to increase their numbers in captivity Generally, the strategy of a captive breeding program is to provide a safe environment for infants and juveniles, the stages at which many animals are most vulnerable to predation and other risks Appropriate imprinting is important to any captive breeding program because animals must develop appropriate behaviors if they are to survive/reproduce in the wild. Exposure during the critical period doesn't just influence the species that juveniles follow around. Young animals can imprint on habitats, food, and future potential mates What behaviors can be influenced by imprinting? Species that juveniles will follow, habitat preference, food preference, and eventual mate choice 35.7 - Animal movement may be a response to stimuli or require spatial learning Kinesis - Random movement in response to a stimulus Taxis - A response directed toward (positive taxis) or away from (negative taxis) a stimulus Spatial Learning - Modification of behavior based on experience of the spatial structure of the environment Kineses and taxes are simple movements in response to a stimulus. Spatial learning involves using landmarks to move through the environment 35.8 - A variety of cues guide migratory movements Migration - Regular back-and-forth movement of animals between two geographic areas at particular times of the year ○ Get food during the year; breed/winter in areas for their survival Migratory animals use external cues to move between areas 35.9 - Animals may learn to associate a stimulus or behavior with a response Associative Learning - check 35.4, photo (e) ○ Example: A cat will learn to associate particular sounds/words/ gestures (stimulus) with specific punishment/reward (outcome). For  example, the sound of a can being opened may bring a cat running for food Trial-and-Error Learning - An animal learns to associate one of its own behaviors with a positive or negative effect ○ Example: Predators learn to associate certain kinds of prey with painful experiences, like a coyote getting hit by a porcupine’s spikes Memory is the key to all associative learning In associative learning, animals learn by associating external stimuli or their own behavior with positive or negative effects 35.10 - Animals can learn from each other Social Learning - check 35.4, photo (e) Many predators learn some hunting tactics from seeing their mothers 35.11 - Problem-solving behavior relies on cognition Cognition - Process carried out by an animal’s nervous system to perceive, store, integrate, and use information gathered by the senses Problem Solving - Process of applying past experience to overcome obstacles One way many animals learn to solve problems is by observing other individual’s behavior Cognition is the process of perceiving, storing, integrating, and using information. Problem-solving behavior involves complex cognitive processes 35.12 - Optimal foraging depends on cost-benefit tradeoffs Foraging - Behavior used in recognizing, searching for, capturing, and consuming food Search Image - A mental picture of the desired food item that enables an animal to find particular foods efficiently ○ If the favored food item becomes scarce, the animal may develop a search image for a different food item ○ Example: People often use search images; for example, when you look for something on a pantry shelf, you probably scan rapidly to find a package of a certain size and color rather than reading all the labels  Optimal Foraging Model - The basis for analyzing behavior as a compromise between feeding costs and feeding benefits Foraging includes identifying, obtaining, and eating food. The optimal foraging model predicts that feeding behavior will maximize energy gain and minimize energy expenditure and risk 35.13 - Communication is an essential element of interactions between animals Signal - A stimulus transmitted by one animal to another animal Communication - Animal behavior including the transmission of, reception of, and response to signals ○ Example: Nocturnal (active at night) mammals use odor/sound signals, which work well in the dark. Diurnal (active at day) mammals use visual/auditory signals. Humans are also diurnal and likewise use mainly visual and auditory signals. ○ Example: Territorial fishes erect their fins. Electrical signals produced by certain fishes communicate hierarchy or status. Fish also use sound to communicate ○ Example: Honeybees use a dance to communicate the location of the food source, as in photo (f) Animals often use more than one type of signal simultaneously (f) Waggle Dance: The bee runs a half circle, then turns and runs in a iiiiiiiiiiiii straight line back to her starting point, buzzing her wings iiiiiii and waggling her abdomen as she goes. She then runs a iii…. half circle in the other direction, followed by another ………………. waggling run to the starting point. The length of the straight. run and the number of waggles indicate the distance to the. food source. The angle of the straight run relative to the ……… vertical surface of the hive is the same as the horizontal …….... angle of the food in relation to the sun Signaling in the form of sounds, scents, displays, or touches provides means of communication 35.14 - Mating behavior often includes elaborate courtship rituals Animals of many species tend to view members of their own species as competitors to be driven away. Even animals that forage/travel in groups often maintain a distance from their companions Careful communication is an essential prerequisite for mating In many species, prospective mates must perform an elaborate courtship ritual, which confirms that individuals are of the same species, of the opposite sex, physically primed for mating, and not threats to each other Differences in courtship behavior are often an effective reproductive barrier between closely related species Courtship rituals reveal the attributes of potential mates 35.15 - Mating systems and parental care enhance reproductive success Courtship and mating are not the only elements of reproductive success. For genes to be passed on to successive generations, the offspring produced by the union must themselves survive and reproduce. Therefore, the needs of the young are an important factor in the evolution of mating systems Animal Mating Systems: ○ Promiscuous - No strong pair-bonds or lasting relationships between males and females ○ Example: Pheasant/Quail/other birds whose young can feed and care for themselves almost immediately after hatching ○ Monogamous - A bond between one male and one female, with shared parental care ○ Example: Most birds ○ Polygamous - An individual of one sex mating with several of the other (1 male + multiple female OR 1 female + multiple male) ○ Example: Pheasant/Quail/other birds whose young can feed and care for themselves almost immediately after hatching 35.16 - Chemical pollutants can cause abnormal behavior Endocrine disruptors enter ecosystems from many of sources ○ Example: Discharge from paper and lumber mills and factory wastes such as dioxin (a by-product of many industrial processes), PCBs  (organic compounds used in electrical equipment until 1977), and methylmercury (from plastic production and coal-fired power plants) Endocrine disruptors are chemicals in the environment that may cause abnormal behavior as well as reproductive abnormalities 35.17 - Social behavior can increase individual fitness Social Behavior - Any kind of interaction between two or more animals, usually of the same species Even social behaviors that benefit others evolve by natural selection. Behaviors that don't benefit an individual or its close kin will be selected against 35.18 - Territorial behavior is a type of resource defense Territory - A specific area that one or more individuals defend and from which other members of the same species are usually excluded The size of the territory varies with the species, the function of the territory, and the resources available. Territories are typically used for feeding, mating, rearing young, or combinations of these activities 35.19 - Agonistic behavior can decrease the costs of aggression Agonistic Behavior - Confrontational behavior involving a contest waged by threats, displays, or actual combat that settles disputes over limited resources, such as food or mates More commonly, animals engage in exaggerated posturing and other symbolic displays that make the individual look large or aggressive 35.20 - Dominance hierarchies are maintained by agonistic behavior Dominance Heirarchy - The ranking of individuals within a group, based on social interactions and usually maintained by agonistic behavior ○ Example: In a wolf pack, there is a dominance hierarchy among the females, and this hierarchy may control the pack’s size. When food is abundant, the alpha female mates and also allows others to do so. When food is scarce, she usually suppresses mating by other females Dominance hierarchies are common, especially in vertebrate populations 35.21 - Altruistic acts can often be explained by the concept of inclusive fitness Many social behaviors are selfish. Behavior that maximizes an individual’s survival and reproductive success is favored by selection, regardless of how much the behavior may harm others Altruism - Behavior that reduces an individual’s fitness while increasing the fitness of others in the population Inclusive Fitness - An individual’s success at perpetuating its genes by producing its own offspring and helping close relatives produce offspring ○ Altruism increases inclusive fitness when it maximizes the reproduction of close relatives Kin Selection - The natural selection that favors altruistic behavior by enhancing reproductive success of relatives Kin selection is a form of natural selection favoring altruistic behavior that benefits relatives. Thus, an animal can propagate its own genes by helping relatives reproduce 35.22 - Jane Goodall revolutionized our understanding of chimpanzee behavior In 1960, paleoanthropologist Louis Leakey, who discovered Homo habilis and its stone tools, thought that studying our closest relatives behavior might provide insight into early human behavior. He hired Jane Goodall to observe chimpanzees in the wild near Lake Tanganyika, Tanzania What she discovered: ○ Chimpanzees make and use tools by fashioning plant stems into probes for extracting termites from their mounds. Until that time, scientists thought only humans had the skill of toolmaking ○ Chimpanzees eat meat as well as plants ○ Close bond between chimpanzee mothers and their offspring ○ Male dominance hierarchy through agonistic displays ○ Lots of fights between the alpha and a regular male ○ They would groom eachother Grooming - Picking through the fur and removing debris or parasites; social glue of a chimpanzee community In decades of fieldwork, she described many aspects of chimpanzee cognition and social behavior 35.23 - ​Human behavior is the result of both genetic and environmental factors Variations in behavioral traits such as personality, temperament, talents, and intellectual abilities make each person a unique individual The abilities to learn, to innovate, to advance technologically, and to participate in complex social networks have been key elements in the phenomenal success of the human species. It is much more likely that natural selection favored mechanisms that enabled humans to operate on the fly, that is, to use experience and feedback from the environment to adjust their behavior according to changing circumstances 36.1 - Population ecology is the study of how and why populations change Population - A group of individuals belonging to one species that live in the same geographic area and can potentially interbreed ○ These individuals rely on the same resources, are influenced by the same environmental factors, and are likely to interact and breed with one another Population Ecology - The study of how members of a population interact with their environment, focusing on factors that influence population density and growth Statistics used to describe a population Population ecologists also examine population dynamics, the interactions between biotic and abiotic factors that cause variation in population sizes One important aspect of population dynamics is population growth Population ecologists might investigate how various environmental factors, such as availability of food, hunting by humans, or forest fires affect the size, distribution, or dynamics of the population Population ecology plays a key role in applied research. Data from population ecology are used to manage wildlife populations, develop sustainable fisheries, and gain insight into controlling the spread of pests and pathogens. Conservationists use these concepts to help identify and save endangered species. Population ecology also includes the study of human population growth, one of the most critical environmental issues of our time A population is a localized group of individuals of a single species 36.2 - Density and dispersion patterns are important population variables Population Density - Number of individuals of a species per unit area or volume ○ Example: Number of oak trees per square kilometer (km2) in a forest Because it is impractical or impossible to count all individuals in a population in most cases, ecologists use a variety of sampling techniques to estimate population densities. ○ Example: They might base an estimate of the density of alligators in the Florida Everglades on a count of individuals in a few sample plots of 1 km2 each The larger the number and size of sample plots, the more accurate the estimates Dispersion Pattern - The manner in which individuals in a population are spaced within their area. There are 3 types: ○ Clumped Dispersion Pattern - A pattern in which the individuals of a population are aggregated in patches; most common in nature; photo (g) ○ Uniform Dispersion Pattern - A pattern in which the individuals of a population are evenly distributed over an area; photo (h) ○ Random Dispersion Pattern - A pattern where individuals of population are spaced in unpredictable way; varying habitat conditions/social interactions make random dispersion rare; photo (i) Population density is the number of individuals in a given area or volume. Environmental and social factors influence the spacing of individuals in various dispersion patterns: clumped (most common), uniform, or random (g) (h) (i) 36.3 - Life tables track survivorship in populations Life Table - A listing of survivals and deaths in a population in a particular time period and predictions of how long, on average, an individual of a given age will live; photo (j) Survivorship Curve - A plot of the number of members of a cohort that are still alive at each age; one way to represent age-specific mortality; photo (k) Life tables and survivorship curves predict an individual’s statistical chance of dying or surviving during each interval in its life. The three types of survivorship curves reflect differences in species’ reproduction and mortality (j) (k) 36.4 - Idealized models predict patterns of population growth Per Capita Rate of Increase - The average contribution of each individual in a population to population growth for a time interval Population growth reflects the number of births minus the number of deaths Exponential Growth Model - A mathematical description of idealized, unlimited population growth; typically a “J” shaped curve The lower part of the J, where the slope of the line is almost flat, results from slow growth when N is small. As the population increases, the slope becomes steeper; photo (l) Limiting Factors - Environmental factors that restrict population growth Logistic Growth Model - A description of idealized population growth that is slowed by limiting factors as the population size increases; photo (m) Carrying Capacity - Maximum population size that a particular environment can sustain Exponential growth is the accelerating increase that occurs when growth is unlimited. The equation G = rN describes this J-shaped growth curve, where G = the population growth rate, r = an organism’s inherent capacity to reproduce, and N = the population size. Logistic growth is the model that represents the slowing of population growth as a result of limiting factors  and the leveling off at carrying capacity, which is the number of individuals the environment can support. The equation G = rN(K−N)/K describes a logistic growth curve, where K = carrying capacity and the term (K − N)/K accounts for the leveling off of the curve l m 36.5 - Multiple factors may limit population growth Density-Dependent Factor - A population-limiting factor whose intensity is linked to population density. For example, there may be a decline in birth rates or a rise in death rates in response to an increase in the number of individuals living in a designated area ○ Density-dependent factors may also depress a population’s growth by increasing the death rate Intraspecific Competition - Competition between members of a population for a limited resource As a limited food supply is divided among more and more individuals, birth rates may decline because individuals have less energy available for reproduction Density-Independent Factor - A population-limiting factor whose intensity is unrelated to population density Over the long term, most populations are probably regulated by a mixture of factors. Some populations remain fairly stable in size and are presumably close to a carrying capacity that is determined by biotic factors such as competition or predation. Most populations for which we have long-term data, however, show fluctuations in numbers. Thus, the dynamics of many populations result from a complex interaction of both density-dependent factors and density-independent abiotic factors such as climate and disturbances Some factors that may reduce birth rate/increase death rate as population density increases are limited food and nutrients, insufficient space, increase in disease and predation  As a population’s density increases, factors such as limited food supply and increased disease or predation may increase the death rate, decrease the birth rate, or both. Abiotic, density-independent factors such as severe weather may limit many natural populations. Most populations are probably regulated by a mixture of factors, and fluctuations in numbers are common 36.6 - Some populations have “boom-and-bust” cycles “Booms” characterized by rapid exponential growth are followed by “busts,” during which the population falls back to a minimal level 36.7 - Evolution shapes life histories Life History - The traits that affect an organism’s schedule of reproduction and death, including age at first reproduction, frequency of reproduction, number of offspring, and amount of parental care Natural selection cannot optimize all of these traits simultaneously because an organism has limited time, energy, and nutrients ○ Example: An organism that gives birth to a large number of offspring will not be able to provide a great deal of parental care R-Selection - Selection for life history traits that maximize reproductive success in environments where resources are abundant Most r-selected species have an advantage in habitats that experience unpredictable disturbances, such as fire, floods, hurricanes, drought, or cold weather, which create new opportunities by suddenly reducing a population to low levels. Human activity is a major cause of disturbance, producing road cuts, freshly cleared fields and woodlots, and poorly maintained lawns that are commonly colonized by r-selected plants and animals K-selection - Selection for life history traits that produce relatively few offspring that have a good chance of survival; occurs when population size is near carrying capacity (K). Natural selection shapes a species’ life history, the series of events from birth through reproduction to death. Populations with so-called r-selected life history traits produce many offspring and grow rapidly in unpredictable environments. Populations with K-selected traits raise few offspring and maintain relatively stable populations. Most species fall between these extremes 36.8 - Principles of population ecology have practical applications Sustainable Resource Management - Management practices that allow use of a natural resource without damaging it  To effectively manage any population, we must identify those variables, account for the unpredictability of the environment, consider the organism’s interactions with other species, and weigh the economic, political, and conservation issues 37.1 - A community includes all the organisms inhabiting a particular area Community - An assemblage of all the populations of organisms living close enough together for potential interaction Community ecology is necessary for the conservation of endangered species and the management of wildlife, game, and fisheries. It is vital for controlling diseases, such as malaria, Zika, and Lyme disease, that are carried by animals. Community ecology also has applications in agriculture, where people attempt to control the species composition of communities they have established Community ecology is concerned with factors that influence the species composition of communities and with factors that affect community dynamics 37.2 - Interspecific interactions are fundamental to community structure Interspecific Interactions - Relationships with individuals of other species in the community; photo (n) Interspecific Competition - When populations of two different species compete for the same limited resource; photo (n) Mutualism - Both partners benefit; photo (n) Predation - One species(predator) kills/eats another species(prey); photo (n) Herbivory - Consumption of plant parts or algae by an animal; photo (n) Interspecific interactions can be categorized according to their effect on the interacting populations (n) (n) 37.3 - Competition may occur when a shared resource is limited Ecological Niche - The role of a species in its community; the sum total of a species’ use of the biotic and abiotic resources of its environment In 1934, Russian ecologist G. F. Gause demonstrated the effects of interspecific competition using three closely related species of ciliates: Paramecium caudatum, P. aurelia, and P. bursaria. He first determined the carrying capacity for each species under laboratory conditions. Then he  grew cultures of two species together. In a mixed culture of P. caudatum and P. bursaria, population sizes stabilized at lower numbers than each achieved in the absence of a competing species—competition lowered the carrying capacity of the environment. On the other hand, in a mixed culture of P. caudatum and P. aurelia, only P. aurelia survived. Gause concluded that the requirements of these two species were so similar that they could not coexist under those conditions; P. aurelia outcompeted P. caudatum for essential resources 37.4 - Mutualism benefits both partners Example: Reef-building corals and photosynthetic dinoflagellates (unicellular algae) provide a good example of how mutualists benefit from their relationship 37.5 - Predation leads to diverse adaptations in prey species Predation benefits the predator but kills the prey. Since predation has such a negative impact on reproductive success in prey populations, numerous adaptations for predator avoidance have evolved in prey populations through natural selection. Examples: Adaptions for predator avoidance ○ Camouflage and color patterns ○ Sharp quills of a porcupine ○ Animals with effective chemical defenses usually have bright color patterns, often yellow/ orange/red with black. Predators learn to associate these color patterns with undesirable consequences, such as noxious taste or a painful sting, and avoid potential prey with similar markings ○ The bright orange/black pattern of monarch butterflies warns potential predators of a nasty taste. Monarchs acquire and store unpleasant chemicals during larval stage, when the caterpillars eat milkweed plants Predation is a powerful factor in the adaptive evolution of prey species because prey that avoid being eaten will most likely survive/reproduce, ­passing alleles for antipredator adaptations on to their offspring 37.6 - Herbivory leads to diverse adaptations in plants Although herbivory isn’t usually fatal, a plant whose body parts have been eaten by an animal must expend energy to replace the loss. Consequently, numerous defenses against herbivores have evolved in plants. Thorns(roses) or spines(cactus) are obvious antiherbivore devices. Chemical toxins are also common defensive adaptations in plants Coevolution - Evolutionary change in which adaptations in one species act as a selective force on a second species, inducing adaptations that in turn act as a selective force on the first species; a series of reciprocal evolutionary adaptations in two interacting species Some herbivore-plant interactions illustrate coevolution or reciprocal evolutionary adaptations 37.7 - Parasites and pathogens can affect community composition Parasite - Lives on or in a host from which it obtains nourishment ○ Internal parasites live inside a host organism’s body. Examples: Flukes, tapeworms, variety of nematodes ○ External parasites attach to their victims temporarily to feed on blood or other body fluids. Examples: Arthropods like ticks, lice, mites, and mosquitoes ○ Plants are also attacked by parasites. Examples: Nematodes and aphids (tiny insects that tap into the phloem and suck plant sap) Pathogens - ­Disease-causing bacteria, viruses, fungi, or protists that can be thought of as microscopic parasites 37.8 - Trophic structure is a key factor in community dynamics Trophic Structure - A pattern of feeding relationships in a community Food Chain - A sequence of food transfers from producers through one to four levels of consumers in an ecosystem; photo (o) This transfer of food moves chemical nutrients and energy from organism to organism up through the trophic levels in a community  Level of Consumers: photo (o) ○ Producers - An organism that makes organic food molecules from CO2, H2O, and other inorganic raw materials Example: Land - plants; Water - phytoplankton ○ Primary Consumers - An herbivore; an organism that eats plants or other autotrophs Example: Land - grasshoppers/other insects, snails, and certain vertebrates like grazing mammals and birds that eat seeds and fruits; Water - variety of zooplankton (mainly protists and microscopic animals such as small shrimps) that eat phytoplankton ○ Secondary Consumers - An animal that eats herbivores Examples: Land - small mammals and a great variety of birds, frogs, and spiders, as well as lions, wolves, and other large carnivores that eat grazers; Water - small fishes that eat zooplankton ○ Tertiary Consumer - An animal that eats secondary consumers ○ Quaternary Consumer - An animal that eats tertiary consumers Detritus - Dead organic matter, including animal wastes, plant litter, and the bodies of dead organisms ○ Examples: Animal wastes, plant litter, bodies of dead organisms Scavenger - An animal that feeds on the carcasses of dead animals ○ Examples: Crows, vultures Detritivore - An organism that consumes decaying organic material ○ Examples: Earthworms, millipedes Decomposer - A prokaryote or fungus that secretes enzymes that digest molecules in organic material and convert them to inorganic forms ○ Examples: Prokaryotes and fungi ○ Lots of microscopic decomposers in the soil/mud at the bottom of lakes/oceans break down most of the community’s organic materials to inorganic compounds that plants/phytoplankton can use Decomposition - The breakdown of organic materials into inorganic ones ○ By breaking down detritus, decomposers link all trophic levels. Their role is essential for all communities and, indeed, for the continuation of life on Earth Eating cheese pizza feeding on these tropic levels: Primary consumer (flour/tomato sauce), and secondary consumer (cheese from cows, which are primary consumers)  Trophic structure can be represented by a food chain 37.9 - Food chains interconnect, forming food webs Food Web - A network of interconnecting food chains; photo (p) Photo (p) - A consumer may eat more than one type of producer, and several species of primary consumers may feed on the same species of producer. Some consumers weave into the food web at more than one trophic level p o 37.10 - Species diversity includes species richness and relative abundance Species Diversity - The variety of species that make up a community. ○ Species richness - the total number of different species ○ Relative abundance of the different species in the community Species diversity also has consequences for pathogens. Most pathogens infect a limited range of host species or may even be restricted to a single host species. When many potential hosts are living close together, it is easy for a pathogen to spread from one to another. More isolated things could escape infection Monoculture - single species grown over a wide area ○ Most modern agricultural systems ○ Low genetic variation = especially vulnerable to pathogens and herbivorous insects ○ Example: Between 1845 and 1849, a pathogen wiped out a monoculture of genetically uniform potatoes throughout Ireland. A million people died of starvation, and well over a million more left the country ○ Farmers/forest managers use 1. Chemical pesticide and 2. Genetic engineering against common pathogens Thus, diversity takes into account both the number of species in a community and the proportion of the community that each species represents 37.11 - Some species have a disproportionate impact on diversity Ecologist Robert Paine hypothesized that the species diversity of a community is directly related to the ability of predators to prevent any one species from monopolizing local resources Keystone Species - A species whose impact on its community is much larger than its abundance or total biological mass would indicate ○ Keystone is the ∩-shaped stone at the top of an arch that holds other pieces in place. If removed, the arch collapses. A keystone species holds a community together Although a keystone species has low biomass or relative abundance, its removal from a community results in lower species diversity 37.12 - Disturbance is a prominent feature of most communities Disturbance - In ecology, an event that changes a biological community by removing organisms from it or altering the availability of resources ○ Example: Storms, fires, floods, droughts, human activities, etc ○ The types of disturbances and their frequency and severity vary from community to community Disturbances aren’t always negative! Example: New habitats are created when a large tree is uprooted in a windstorm. More light reaches the forest floor, giving small seedlings the opportunity to grow, or the hole left by the tree’s roots may fill with water and be used as egg-laying sites by frogs, salamanders, and numerous insects ○ Communities change drastically following a severe disturbance that strips away vegetation and even soil Ecological Succession - The process of biological community change resulting from disturbance; transition in the species composition of a biological community Primary Succession - A type of ecological succession in which a biological community arises in an area without soil ○ Example: Rubble left by a retreating glacier, fresh volcanic lava flows ○ Primary succession can take hundreds or thousands of years Secondary Succession - A type of ecological succession that occurs where a disturbance has destroyed an existing biological community but left the soil intact ○ Example: This occurs as areas recover from fires or floods ○ Some disturbances are caused by human activities. Whenever human intervention stops, secondary succession begins Disturbances may also create opportunities for undesirable plants and animals that people transport to new habitats Ecological succession is a transition in species composition of a community. Primary succession is the gradual colonization of barren rocks. Secondary succession occurs after a disturbance has destroyed a community but left the soil intact 37.13 - Invasive species can devastate communities For as long as people have traveled from one region to another, they have carried organisms along, both intentionally and by accident. Many of these  non-native species have established themselves firmly in their new locations. Invasive Species - A non-native species that spreads beyond its original point of introduction and causes environmental or economic damage ○ Example: Burmese Python brought from Asia to the US. They found their way to the Florida Everglades and now have grown to a huge population. Populations of native mammals (deer/marsh rabbits/bobcats) have declined steeply in the park since they are prey ○ These species spread far beyond their original point of introduction and causing environmental or economic damage by colonizing and dominating wherever they find a suitable habitat ○ In the United States alone, there are hundreds of invasive species, including plants, mammals, birds, fishes, arthropods, and molluscs. Worldwide, there are thousands more. Invasive species are a leading cause of local extinctions ○ The ­economic costs of invasive species are enormous - more than $100 billion a year in the US. Regardless of where you live, an invasive plant or animal is probably nearby Every population in a community is subject to harmful interspecific interaction from competitors/predators/herbivores/pathogens. Without biotic factors (as above) to stop the growth, it will continue to grow until limited by abiotic factors. The damage caused by invasive species often results from interspecific interactions between it and native species Organisms that have been introduced to non-native habitats by human actions and have established themselves at the expense of native communities are considered invasive 37.14 - Ecosystem ecology emphasizes energy flow and chemical cycling Ecosystem - All the organisms in a given area, along with the nonliving factors with which they interact; a biological community and its physical environment Energy Flow - The passage of energy through the components of an ecosystem Chemical Cycling - The transfer of materials, such as carbon, within an ecosystem In photo (q) - Energy enters the terrarium in the form of sunlight (↝). Plants (producers) convert light energy to chemical energy (→) through the process  of photosynthesis. Animals (consumers) take in some of this chemical energy, which is stored in organic compounds, when they eat the plants. Decomposers, such as bacteria and fungi in the soil, obtain chemical energy when they decompose the dead remains of plants and animals. Every use of chemical energy by organisms involves a loss of some energy to the surroundings in the form of heat (↝). In contrast to energy flow, chemical cycling (↻) involves the transfer of matter within the ecosystem. While most ecosystems have a constant input of energy from sunlight, the supply of the chemical elements used to construct molecules is limited. Chemical elements such as carbon and nitrogen are cycled between the abiotic components of the ecosystem, including air, water, and soil, and the biotic component of the ecosystem (the community). Plants acquire these chemical elements in inorganic form from the air and soil and use them to build organic molecules. Animals, such as the snail, consume some of these organic molecules. When the plants and animals become detritus, decomposers return most of the elements to the soil and air in inorganic form. Some elements are also returned to the soil and air as the by-products of plant and animal metabolism Both energy flow and chemical cycling involve the transfer of substances through the trophic levels of the ecosystem. However, energy flows through, and ultimately out of, ecosystems, whereas matter is recycled within ecosystems An ecosystem includes a community and the abiotic ­factors with which it interacts; photo (r) q r 37.15 - Primary production sets the energy budget for ecosystems Each day, Earth receives about 1019 kcal of solar energy, the energy equivalent of 100 million atomic bombs. Most of this energy is absorbed, scattered, or reflected by the atmosphere or by Earth’s surface. Of the  visible light that reaches plants, algae, and cyanobacteria, only about 1% is used for primary production Primary Production - The conversion of solar energy to chemical energy as organic compounds by photosynthesis Gross Primary Production - The total primary production of an ecosystem during a given time period; expressed in units of energy/biomass (mass of vegetation) Earth’s gross primary production is roughly 165 billion tons of organic material per year. Producers use some of this organic material to fuel their own cellular respiration Net Primary Production - The gross primary production of an ecosystem minus the energy used by the producers for respiration; the stored chemical energy that is available to consumers in an ecosystem Different ecosystems vary …………considerably in their primary …………production as well as in their …………contribution to the total production of …………the biosphere; photo (s) s 37.16 - Energy supply limits the length of food chains When organic material is transferred from one trophic level to the next (that is, when one organism consumes another), much of its stored energy is lost ○ Example: A caterpillar might digest/absorb only about half the organic material it eats, turning the rest into feces An energy pyramid shows the loss of energy with each transfer in a food chain. Each tier represents the chemical energy present in all organisms at one trophic level of a food chain. The width of each tier indicates how much of the chemical energy of the tier below is actually incorporated into the biomass of that trophic level. Idealized energy pyramid - photo (t) Energy pyramids show us why food chains are limited from three-five levels; there isn’t enough energy at the top to support another trophic level An energy pyramid shows the flow of energy from producers to primary consumers and to higher trophic levels. Only about 10% of the energy stored at each trophic level is available to the next level  t u 37.17 - An energy pyramid explains the ecological cost of meat Primary Consumers - grain/fruit; Secondary Consumers - beef/other meat from herbivores; Tertiary/Quaternary Consumers - fish like trout/salmon (which eat insects and other small animals) 37.18 - Chemicals are cycled between organic matter and abiotic reservoirs Biogeochemical Cycle - Any of the various chemical circuits that involve both biotic and abiotic components of an ecosystem; can be local or global Abiotic Resevoirs - The part of an ecosystem where a chemical, such as carbon or nitrogen, accumulates or is stockpiled outside of living organisms In photo (u) - 1) Producers incorporate chemicals from abiotic reservoirs into organic compounds. 2) Consumers feed on producers, incorporating some chemicals into their bodies. 3) Both producers and consumers release some chemicals back to environment in waste products (CO2/nitrogenous wastes of animals). 4) Decomposers play a central role by breaking down complex organic molecules in detritus such as plant litter/animal wastes/dead organisms. The products of this metabolism are inorganic compounds such as nitrates (NO3−)/phosphates (PO43−)/CO2, which replenish abiotic reservoirs. Geologic processes like erosion/weathering of rock also contribute to abiotic reservoirs. Producers use inorganic molecules from abiotic reservoirs as raw materials for synthesizing new organic molecules (carbohydrates, proteins, etc.) and the cycle continues 37.19 - The carbon cycle depends on photosynthesis and respiration Carbon - Major ingredient of all organic molecules; has an atmospheric reservoir; cycles globally; resides in plant/animal biomass, fossil fuels, soils, sedimentary rocks, and dissolved carbon compounds in oceans In photo (v) - 1) Photosynthesis removes CO2 from atmosphere and turns it to organic molecules, which are 2) passed along food chain by consumers. 3) CR by producers/consumers returns CO2 to atmosphere. 4) Decomposers break down carbon compounds in detritus; that carbon is also released as  CO2. The return of CO2 to atmosphere by CR balances its removal by photosynthesis. However, 5) increased burning of wood/fossil fuels (coal/petroleum) is raising level of CO2 in atmosphere v w CR↑ 37.20 - The phosphorus cycle depends on the weathering of rock In photo (w) - 1) Breakdown of rock gradually adds inorganic phosphate (PO43−) to soil. 2) Plants assimilate dissolved phosphate ions in soil and build them into organic compounds. 3) Consumers obtain phosphorus in organic form by eating plants. 4) Phosphates are returned to soil by action of decomposers on animal waste and remains of dead plants/animals. 5) Some phosphate drains from terrestrial ecosystems into sea, where it settles, becoming part of new rocks. This phosphorus won’t cycle back into living organisms until 6) geologic processes uplift rocks and expose them to weathering, a process that takes millions of years Phosphates are transferred from terrestrial-aquatic ecosystems faster than they’re replaced so amount in terrestrial ecosystems lowers over time. Also, much of soluble phosphate released by weathering quickly binds to soil particles, making it inaccessible to plants. As a result, phosphate availability is low and a limiting factor 37.21 - The nitrogen cycle depends on bacteria As an ingredient of proteins/nucleic acids, nitrogen is essential to the structure and functioning of all organisms. It is crucial and a limiting plant nutrient. Nitrogen has 2 abiotic reservoirs, the atmosphere/the soil. The atmospheric reservoir is huge; almost 80% of the atmosphere is nitrogen gas (N2). However, plants cannot absorb nitrogen in the form of N2. Nitrogen  fixation, which is performed by bacteria, converts N2 to compounds of nitrogen that plants can use. Without these organisms, the natural reservoir of usable soil nitrogen would be limited Nitrogen Fixation - The conversion of atmospheric nitrogen (N2) to nitrogen compounds (NH4+, NO3−) that plants can absorb and use In photo (x) - 1) Some bacteria live symbiotically in roots of certain plants, supplying their hosts with a direct source of usable nitrogen. The largest group of plants with this mutualistic relationship is the legumes (peanuts/soybeans/alfalfa). A number of nonlegume plants that live in nitrogen-poor soils have a similar relationship with bacteria. 2) Free-living ­nitrogen-fixing bacteria in soil or water convert N2 to ammonia (NH3), which then picks up another H+ to become ammonium (NH4+). 3) After nitrogen is “fixed,” some of the NH4+ is taken up and used by plants. 4) Nitrifying bacteria in soil also convert some NH4+ to nitrate (NO3−) which is readily 5) assimilated by plants. Plants use the nitrogen they assimilate to synthesize molecules like amino acids, which are incorporated into proteins. 6) When an herbivore eats a plant, it digests proteins into amino acids, then uses them to build proteins it needs. Higher-order consumers gain nitrogen from prey. Nitrogen-containing waste products are formed during protein metabolism; consumers excrete some nitrogen and incorporate some into their body tissues. Mammals excrete nitrogen as urea; industrially produced urea is widely used as agricultural fertilizer. Organisms that aren’t consumed eventually die and become detritus, which is decomposed by prokaryotes/fungi. 7) Decomposition releases NH4+ from organic compounds back into soil, replenishing soil reservoir of NH4+ and, with nitrifying bacteria (step 4), NO3−. Under low-oxygen conditions, however, 8) soil bacteria known as denitrifiers strip oxygen atoms from NO3−, releasing N2 back in the atmosphere and depleting soil reservoir of usable nitrogen Some NH4+/NO3− are made in atmosphere by chemical reactions involving N2 and ammonia gas (NH3). These ions reach soil in precipitation/dust, which are crucial sources of nitrogen for plants in some ecosystems Human activities are disrupting nitrogen cycle by adding more nitrogen to biosphere each year than that added by natural processes. Combustion of fossil fuels in motor vehicles/coal-fired power plants produces nitrogen oxides (NO/NO 2). Nitrogen oxides react with other gases in lower atmosphere to increase production of ozone (O3). Unlike ozone layer in upper atmosphere, which protects Earth from  harmful ultraviolet radiation, ground-level ozone is a health hazard. It irritates respiratory system and causes coughing/breathing difficulties. High ozone levels are especially dangerous for people with respiratory problems like asthma. In many regions, ozone alerts are common during hot/dry summer weather. Nitrogen oxides also combine with water in atmosphere to become nitric acid. The Clean Air Act Amendments of 1990 led to diminished acid precipitation from sulfur emissions, but environmental damage from nitric acid precipitation is causing new concern Modern agricultural practices are another source of nitrogen. Animal wastes from intensive livestock production release ammonia in atmosphere. Farmers use amounts of nitrogen fertilizer to supplement natural nitrogen fixation by bacteria. Worldwide, application of synthetic nitrogen fertilizer has increased 100-fold since late 1950s. However, less than half fertilizer is taken up by crop plants. Some nitrogen escapes to atmosphere, where it forms NO2/nitrous oxide (N2O), an inert gas that lingers in atmosphere and contributes to global warming. Nitrogen fertilizers also pollute aquatic systems Various bacteria in soil (and root nodules of some plants) convert gaseous N2 to ­compounds that plants can use, such as ammonium (NH4+) and nitrate (NO3−) x 37.22 - A rapid inflow of nutrients degrades aquatic ecosystems Low levels of nutrients, especially phosphorus/nitrogen, limit growth of algae/cyanobacteria and primary ­production in aquatic ecosystems. Standing-water ecosystems (lakes/ponds) accumulate nutrients from decomposition of organic matter/fresh influx from land. Result = primary production increases naturally over time in eutrophication. Human activities  that add nutrients to aquatic ecosystems accelerate this/cause eutrophication in rivers/estuaries/coastal waters/coral reefs Rapid eutrophication lowers species diversity. In some ecosystems, cyanobacteria replace green algae as primary producers. These prokaryotes, which are encased in slimy coating, form extensive mats on surface of the water that prevent light from penetrating the water. Some species of cyanobacteria can fix nitrogen, which gives them additional advantage when phosphate is pollutant and nitrogen is scarce. Other ecosystems are overrun by blooms of unicellular diatoms, toxin-producing dinoflagellates. These heavy growths of cyanobacteria/algae reduce oxygen levels at night, when photosynthesizers respire. As cyanobacteria, or algae die, microbes consume lots of oxygen as they decompose extra biomass. Thus, rapid nutrient enrichment results in oxygen depletion of water. Fishes that have high oxygen requirement can’t survive in this environment Oxygen depletion disrupts benthic communities, displacing fishes and invertebrates that move and killing organisms attached to the substrate Nutrient input from fertilizer and other sources causes rapid eutrophication, resulting in decreased species diversity and oxygen depletion of lakes, rivers, and coastal waters 37.23 - Ecosystem services are essential to human well-being Natural ecosystems provide direct benefits to people by supplying us with fresh water/food. Natural vegetation helps retain fertile soil/prevent landslides/mudslides. We need healthy ecosystems to recycle nutrients, decompose wastes, and regulate climate/air quality. Wetlands buffer coastal populations against tidal waves/hurricanes, reduce impact of flooding rivers, and filter pollutants. We need the ecosystems we make, like agricultural ecosystems supply most of our food/fibers Soil fertility (foundation for crop growth) depends on nutrient cycling. Large inputs of chemical fertilizers are needed to supplement soil nutrients. Synthetic pesticides are used to control population growth of crop-eating insects/pathogens that take advantage of vast monocultures of crop species. Herbicides are used to kill weeds that compete with crop plants for water/nutrients. Crops also need more water from irrigation  The growing demand of the human population for food, fibers, and water has largely been satisfied at the expense of other ecosystem services Climate change brings more torrential rains so inland wetlands provide essential flood protection for farms/cities downstream. They also store water in soil and help recharge aquifers, ensuring survival of biological ­communities and crops during periods of drought. However, half of the world’s wetlands have been lost since 1900, destroyed by development, invasive species, nutrient pollution, drainage for agriculture, damming rivers, and siphoning off freshwater for burgeoning populations. In 2009 ( last year for which data is available), coastal wetlands were disappearing from US at 325 km2 per year Sustainability - The goal of developing, managing, and conserving Earth’s resources in ways that meet the needs of people today without compromising the ability of future generations to meet theirs We depend on services provided by natural ecosystems 38.1 - Loss of biodiversity includes the loss of ecosystems, species, and genes Biodiversity - The variety of living things; includes genetic diversity, species diversity, and ecosystem diversity 20% of the world’s coral reefs have been destroyed by human activities, and 15% are in danger of collapse within the next two decades. Tens of thousands of species live in lakes and rivers, and they supply food and water for many species like us Nearly half of Earth’s forests are gone, and thousands more square kilometers disappear every year. Grassland ecosystems in North America have been lost to agriculture and development Extirpation - The loss of a single population of a species Extinction - The irrevocable loss of a species The loss of one species can have a negative impact on the overall species richness of the ecosystem. Keystone species illustrate this effect Two reasons to be concerned about the impact of the biodiversity crisis on human welfare are that the environmental degradation threatening other species may also harm us. We are dependent on biodiversity, both directly through the use of organisms and their products and indirectly through ecosystem services Although valuable for its own sake, biodiversity also provides food, fibers, medicines, and ecosystem services 38.2 - Habitat loss, invasive species, overharvesting, pollution, and climate change are major threats to biodiversity Human alteration of habitats poses the greatest threat to biodiversity throughout the biosphere. Agriculture/urban development forestry/mining/environmental pollution have brought massive destruction and fragmentation of habitats. Deforestation continues rapidly in tropical and coniferous forests. The amount of land surface altered by people is approaching 50%, and we use more than half of all accessible surface fresh water. The natural courses of most of the world’s major rivers have been changed. Worldwide, tens of thousands of dams constructed for flood control, hydroelectric power, drinking water, and irrigation have damaged river and wetland ecosystems. Some of the most productive aquatic habitats in estuaries and intertidal wetlands have been overrun by commercial and residential development. The loss of marine habitat is severe, especially in coastal areas and coral reefs Invasive species disrupts communities by competing with/preying on/parasitizing native species. A lack of interspecific interactions that keep the newcomer populations in check is often a key factor in a non-native species becoming invasive. Meanwhile, newly arrived species is an unfamiliar biotic factor in environment of native species. Natives are vulnerable when new species pose unprecedented threats. In absence of evolutionary history with predators, animals may lack defense mechanisms/a fundamental recognition of danger. Pollutants released by human activities can have local/regional/global effects. Some pollutants, like oil spills, contaminate limited region. The global water cycle can transport pollutants. Pollutants emitted in atmosphere, like nitrogen oxides from burning of fossil fuels, may be carried aloft for miles before falling to Earth in form of acid precipitation Ozone Layer - The layer of ozone (O3) in the upper atmosphere that protects life on Earth from the harmful ultraviolet rays in sunlight Biological Magnification - The increasing concentration of harmful chemicals that are retained in the living tissues at each level of a food chain Human alteration of habitats is the single greatest threat to biodiversity. Invasive species disrupt communities by competing with, preying on, or parasitizing native species. Harvesting at rates that exceed a population’s  ability to rebound is a threat to many species. Human activities produce diverse pollutants that may affect ecosystems far from their source. Biomagnification concentrates synthetic toxins that cannot be degraded by organisms 38.3 - Rapid warming is changing the global climate Rising concentrations of greenhouse gases in the atmosphere, such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), resulting from human activities, are changing global climate patterns The main effect of increasing greenhouse gases is the rapid increase in the average global temperature, which has risen about 1.8°F since 1900 at an accelerating pace. A 2018 Intergovernmental Panel on Climate Change (IPCC) report predicts that keeping the rise to below 2.7°F is possible only with extreme reductions in greenhouse gas emissions. Temperature increases aren’t distributed evenly around the globe. The largest increases are in the northernmost regions of the Northern Hemisphere. In picture (y/z), red and dark orange areas indicate the greatest temperature increases. In parts of Alaska and Canada, the average winter temperature has risen more than 6°F since 1961 More than 90% of heat trapped by greenhouse gases is stored in ocean. From 1995 to 2015, the heat content of upper ocean increased by 1.3 × 1017 kcal per year, energy roughly equivalent to over 5 million atomic bombs. Water expands as it warms, causing sea level to rise. Melting of massive ice sheets of Greenland/Antarctica and mountain glaciers contributes to sea level rise. As this trend accelerates, rising sea level will cause flooding of coastal areas worldwide Consequences of global warming include more extreme weather events. Precipitation patterns are changing, bringing longer/more intense drought to areas. In other regions, a greater proportion of total precipitation is falling in torrential downpours that cause flooding. Hurricane intensity is increasing, fueled by higher sea surface temperatures Seasonal changes are occurring. Warm weather is beginning earlier each year. Cold days/nights and frosts have become less frequent; hot days and nights have become more frequent. Deadly heat waves are increasing in frequency/duration Increased global temperature caused by rising concentrations of greenhouse gases is changing climate patterns, with grave consequences  y z 38.4 - Human activities are responsible for rising concentrations of greenhouse gases {photo (1b) is just a diagram to show increase over time} In photo (1a) - CO2 is removed from atmosphere by the photosynthesis and stored in organic molecules like carbohydrates (↓). Thus, all of the organic material in an ecosystem is a carbon reservoir. (⤴) represent carbon released in the form of CO2. The carbon-containing molecules in living organisms may be used in process of cellular respiration. Cellular respiration by microorganisms/fungi as they decompose nonliving organic material also releases CO2. Overall, uptake of CO2 by photosynthesis roughly equals release of CO2 by cellular respiration. In addition, CO2 is exchanged between atmosphere and surface waters of oceans Fossil fuels consist of dead organisms buried under sediments for years without being decomposed. The burning of fossil fuels/wood (organic material) is a form of decomposition. Whereas CR releases energy from organic molecules slowly and harnesses it to make ATP, combustion liberates energy rapidly as heat/light. In both processes, the carbon atoms that make up the organic fuel are released in CO2 The CO2 flooding into atmosphere from combustion of fossil fuels may be absorbed by photosynthetic organisms and incorporated into biomass. But deforestation has decreased number of CO2 molecules that can be accommodated by this pathway. CO2 may be absorbed into the ocean. For decades, the oceans have been absorbing considerably more CO2 than they have released, and they will continue to do so, but the excess CO2 is beginning to affect ocean chemistry. When CO2 dissolves in water, it becomes carbonic acid. Recently, measurable decreases in ocean pH have raised concern among biologists. Organisms that construct shells/exoskeletons out of calcium carbonate (CaCO3), including  corals/many plankton, are most likely to be affected, as decreasing pH reduces concentration of carbonate ions 1b 1a 38.5 - Climate change affects biomes, ecosystems, communities, and populations The distribution of terrestrial biomes, which is primarily determined by temperature/rainfall, is changing as consequence of global warming. Researchers have documented more than a dozen locations around the world where ranges of shrubs/conifers have stretched into regions that were once tundra. Prolonged droughts will increasingly extend the boundaries of deserts. Great expanses of Amazonian tropical rain forest will gradually become savanna as increased temperatures dry out the soil The earlier arrival of warm weather in the spring is disturbing ecological communities in other ways. In many species, certain events are triggered by rising spring temperatures. Earlier temperature increases have hastened breeding season for some animal species. Earlier greening of the landscape occurs, and flowering occurs sooner. For other species, day length is cue that spring has arrived. Because global warming affects temperature but not day length, interactions between species may become out of sync. Plants may bloom before pollinators have emerged, or eggs may hatch before dependable food source for the young is available. Because magnitude of seasonal shifts increases from tropics to poles, migratory birds may also experience timing mismatches. For instance, birds arriving in Arctic to breed may find that period of peak food availability has passed Warming oceans threaten tropical coral reef communities. When stressed by high temperatures, corals expel symbiotic algae in bleaching. Corals can recover if temperatures return to normal, but cannot survive prolonged temperature increases. When corals die, the community is overrun by large algae, and species diversity plummets  Climate change has helped some organisms, but so far the beneficiaries have been species that have a negative impact on humans Organisms that live at high latitudes and high elevations are experiencing the greatest impact 38.6 - Climate change is an agent of natural selection Phenotypic Plasticity - The ability of an organism’s physiology and anatomy to adjust to local environmental conditions Phenotypic plasticity allows organisms to cope with short-term environmental changes. On the other hand, phenotypic plasticity is itself a trait that has a genetic basis and can evolve. Researchers studying the effects of climate change on populations have detected microevolutionary changes in phenotypic plasticity The rate of climate change is incredibly fast compared with major climate shifts in evolutionary history, and if it continues on its present course, thousands of species will likely become extinct Phenotypic plasticity has minimized the impact on some species, and several cases of microevolutionary change have been observed. However, the rapidity of the environmental changes makes it unlikely that evolutionary processes will save many species from extinction