Disease Detective And Ecology Notes PDF

Ecology Ecology Definition: the scientific study of the relationship of living organisms with each other and with their environment - The term ecology was first named in 1869 by the German biologist Ernst Haeckel. It has been derived from two Greek words, ‘oikos’,...

Ecology Ecology Definition: the scientific study of the relationship of living organisms with each other and with their environment - The term ecology was first named in 1869 by the German biologist Ernst Haeckel. It has been derived from two Greek words, ‘oikos’, meaning home or estate, and ‘logos’ meaning study. Levels of Ecological Organization Organism Any living thing that has living characteristics and is composed of one or more cells. Population Populations are groups of individuals of the same species taking up a common geographical area. Community More than 2 populations of different species are living together at the same time and place. Ecosystem Communities of organisms that are interacting together in their physical environment. Biome The community of plants and animals that occur naturally in an area; sometimes share common characteristics depending on their specific area. Biosphere A thin layer around and on the earth that contains life. All of the organisms in the biosphere are indirectly or directly dependent on each other including the physical parts of the earth. The atmosphere, lithosphere, and hydrosphere (air, land, and water) are the three physical parts of the earth. Environment - Environment denotes all the physical, chemical, and biotic conditions surrounding and influencing a living organism. Favorable environmental conditions are required to sustain life on Earth. - The environment can be divided into two main components: Non-living and Living 1. Abiotic or Non-living components - The physical (climatic), edaphic (nature of soil), and chemical. For example, temperature, light, pressure, humidity, precipitation, wind, soil mineral elements, and air composition. Some of these environmental factors serve as resources(air, soil, and water)While others act as regulatory factors (light, temperature, pressure, etc.) 2. Biotic or Living components include All living organisms found in the environment including plants, animals, and microorganisms Organization of life Various levels or organizations exist in the living systems starting from the molecules such as DNA (genes) to the whole biosphere. The levels of organization are as follows: Genes - Cell - Organ - Organism -Species Population - Community -Ecosystem - Biome - Biosphere Niche and Organism In nature, many species occupy the same habitat but perform different functions. The functional characteristics of a species in its habitat are referred to as niches. While the habitat of a species is like its address, a niche can be thought of as its profession. The term niche means the sum of all the activities and relationships of a species by which it uses the resources in its habitat for its survival and reproduction. A niche is unique for a species while many species may share the same habitat. No two species can have the same niche, otherwise, they will compete with one another until one is displaced. For example, different species of insects may be pests of the same plant but they can co-exist because they feed on different parts of the same plant that is because their niches are different. When animals co-exist, but neither help nor hurt other species is called commensalism. Adaptation Every organism is suited to live in its particular habitat. You know that coconuts are adapted for growing in water while a camel is adapted for life in the desert. An adaptation is thus, the appearance, behavior, structure, or mode of life of an organism that allows it to survive in a particular environment. Population Population is defined as the group of freely interbreeding individuals, often the same species present in a specific geographical area at a given time. A population has traits of its own that are different from those of the individuals forming the population. For example,(1) an individual is born and dies but a population continues. Population may change in size depending on birth and death rates of the population,(2) an individual is either female or male, young or old, but a population has a sex ratio which means, the ratio of male to female in the population which also has,(3) age structure, which means the various age groups into which population may be divided. The characteristics of any population depend on the following factors. (1)density of the population,(2)natality,or birth rate,(3) mortality, or death rate.(4) dispersal,(5) biotic potential,(6)age distribution,(7)dispersion,(8) growth form. Density The number of individuals per unit area at a given time is termed population density which may vary from time to time and place to place. The density of a particular organism in a region is determined by selecting random samples from an area of a particular dimension called a quadrat from that region. In the case of large mobile animals like tigers, leopards, lions, deer, etc. the density may be determined by counting individual animals directly or by the pugmarks left by the animals in a defined area. Birth Rate of Natality The rate at which new individuals are born and added to a population under given environmental conditions is called natality. Death rate or Mortality Loss of individuals from a population due to death under given environmental conditions is called mortality. Dispersal The movement of individuals of a population out of a region permanently is termed emigration. Immigration refers to the movement of individuals into a new area. Dispersal includes both emigration (going away permanently from an area) and immigration(influx of new individuals into an area) Variation -Variations are heritable -Species are generally composed of several distinct; populations that freely interbreed even though they appear to be different in appearance -Differences in the color of skin, type of hair; curly or straight, eye color, and blood type among different ethnic groups represent variation within the human species, similarly, different shapes and sizes of cows, dogs, and cats, etc. Interdependence -the survival of species is dependent on other living organisms and nonliving component Generalists -eat a variety of food (ex:pig) Taxonomy -field of biology that classifies organisms, organizing them based on similar characteristics Domain Kingdom Phylum Class Order Family Genus Species Natural Selection is a type of evolution(change over time) Natural Selection is a type of evolution(change over time) Same species -can breed with each other -can pass down DNA to offspring -have variety of traits -some can blend in better Density-Dependent Factors -limiting resources (e.g.,food & shelter) -production of toxic wastes -infectious diseases -predation -stress -emigration -severe storms and flooding -sudden unpredictable severe cold spells -earthquakes and volcanoes -catastrophic meteorite impacts K-Selected Species -poor colonizers -Slow maturity -long-lived -low fecundity -high investment in care for the young specialist -good competitors R-Selected Species -Good colonizers -Reach sexual maturity rapidly -Short-lived -High fecundity -Generalists -Poor competitors Specialists -eat few or even one type of food (ex:panda) Characteristics of Life -be composed of one (unicellular) or more cells (multicellular) -contain either DNA or RNA as their genetic material -be capable of growth/become bigger -be capable of reproducing -demonstrate the ability to respond to outside stimuli -as a population,be able to adapt to the environment and evolve -have a metabolism, meaning bothe consume energy and produce waste -”Cells, Cells, Cells, Respond, Grow and Reproduce, Use Energy, Have DNA, Adaptive Living Dudes. Stimulus -a change in organism’s environment Evolution A valid theory of evolution was proposed by Charles Darwin and Alfred Wallace in 1859. This theory has been extended in the light of progress in genetics and is known as Neo-Darwinism. (1) Organisms tend to produce more offspring that can be supported by the environment. (2) An evolutionary force (natural selection), selects among variations Speciation Is the process by which new species are formed and evolution is the mechanism by which speciation is brought about -A species comprises many populations. Often different populations of a species remain isolated due to some geographic barrier -Isolation occurs when a physical barrier develops between two populations of a species. The most common way a population undergoes species isolation is by geographic isolation. The members of a population of a species live in a particular environment and are capable of breeding with the members of another population of the same species. -The population then becomes separated into two completely isolated populations by a barrier that prevents their interbreeding and gene exchange, Geographical isolation-water, mountain, ocean Ecological isolation-temperature, humidity, pH Reproductive isolation-interference in interbreeding between members of different populations of species Reproductive isolation can occur due to one of the following reasons (1) When two different populations become sexually receptive at different times of the year (2) Members of different populations are not attracted by courtship behavior toward one another (3) Pollination mechanism fails, between flowers of two populations (4) Cross-fertilization is prevented as sex organs of different populations of a species do not match Mutations -Mutation(a change in the genetic material that results from an error in the replication of DNA)causes new genes to arise in a population, Farthing in a sexually reproducing population, meiosis and fertilization produce a new combination of genes every generation, which is termed recombination. Thus members of the same species show variation and are not identical -Mutations occur randomly in isolated populations leading to new variation within each subpopulation of these mutations those that help to adapt the the environment are reproduced in greater numbers in the next generation due to natural selection An Example of Formation of New Species A current example of specifications can be seen in the two species of squirrels Kaibab squirrels and Abert squirrels that live on opposite sides of the Grand Canyon. Biologists assume that the two squirrel populations became separate species when about one million years ago, the Colorado River changed its course, splitting the original population of squirrels into two. Since the environment on opposite sides of the canyon is different, different characteristics were favored on each side of the canyon, by natural selection, After many years of separation, the genetic differences between the populations became so large that the two squirrel populations became two separate species. They look different and can no longer interbreed Under the 2nd law of thermodynamics, there is a decrease in the amount of energy available to each succeeding organism in a food chain or web. Every time a predator eats prey, the energy they get is 10% of the prey’s energy. (90% lost; 10% gained)  Symbiosis Mutualism = Both organisms benefit. Commensalism = One benefits, other unharmed nor helped Parasitism = One benefits, other gets harmed or hurt(benefits community biodiversity) Week 2 What is a population? A population includes all the organisms that belong to the same species that are living within a designated area and can interact, breed, and have offspring Population ecology is the study of these populations Population ecologists study different species around the world for many important reasons including -determining which species need protection, such as endangered species -Managing economically valuable species, such as commercial fisheries -Controlling pest species and invasive species Range = the geographic area where a species can be found -Factors such as the time of year, breeding activity, and where a species historically originated can all determine its range -A range map shows the distribution and boundary line of a population Population Distribution = spacing and location of individuals within their range -Both behavioral and ecological factors can influence a population distribution -Understanding a population’s distribution is essential for healthy population management Clumped Distribution Organisms are grouped in clusters -Found in environments with unevenly distributed resources -Organisms may be clustered together due to social factors, such as family groups -Organisms may also group to hunt more effectively or to protect themselves from predators Uniform Distribution Organisms are evenly spaced from one another -Found in populations where the distance between organisms is maximized -Spacing is often a result of competition -Farming and agricultural practices showcase man-made uniform distribution Random Distribution ORganism is random speed. -Occurs when organisms of a species are in environments where the position of each individual is independent of all other individuals -Often a lack of social interaction within the species -More likely to occur where environmental conditions are consistent Factors affecting species distribution Abiotic factors -Climatic factors (precipitation, sunlight, humidity, sunlight, temperature, pH) -Local geography(soil, terrain, elevation) -Resource availability(nutrients, water) Population Growth Exponential growth: Populations that increase without any limits to their growth Logistic growth: Limits that get introduced to reproductive growth which becomes way more intense as the population size is increasing The population growth rate (sometimes called the rate of increase or per capita growth rate, r) equals the birth rate (b) minus the death rate (d) divided by the initial population size N(o) The population growth rate (r) -r=(b-d)/N(0) The doubling time is how long it will take for a population to become twice its initial size. Doubling time: t Growth rate: r The doubling time is equal to t=0.69/r Sometimes population ecologists round this equation to 0.70 for simplicity. Four factors determine the population growth rate using 4 factors Births Deaths Immigration Emmigration - Populations with unlimited natural resources overgrow, and then population growth decreases as resources become depleted. This accelerating pattern of increasing population size is called exponential growth. - Bacteria are prokaryotes that reproduce quickly, about an hour for many species. - If 1000 bacteria are placed in a flask (unlimited supplies), in one hour, there will be 2000 bacteria. - When a species is introduced into a new habitat that it finds suitable, it may show exponential growth for a while. - Exponential growth is only possible when infinite natural resources are available; this is not the case in the real world. - In the real world, exponential growth is limited by resources. Initially exponential, the growth rate slows and levels off at carrying capacity. - Carrying capacity is the number of organisms that an ecosystem can sustainably support. - The logistic growth formula includes carrying capacity to moderate growth. "K-N" shows potential population growth. "K-N" divided by "K" is the available capacity for growth. This factor limits exponential growth, forming logistic growth.  - - When N is small, (K-N)/K is close to 1, resulting in exponential growth unaffected by carrying capacity. In large populations, (K-N)/K approaches 0, significantly slowing or stopping growth. Negative growth occurs when the population exceeds carrying capacity. - The resulting competition between population members of the same species for resources is termed intraspecific competition (intra- = “within”; -specific = “species”). - Interspecific competition is the competition between individuals of different species. - Population growth in some groups can be rapid until resources dwindle, causing a sudden decline rather than a gradual decrease. - The logistic model of population growth simplifies real-world dynamics, as it assumes a constant carrying capacity in the environment, which varies due to factors like seasons and natural events. Populations also interact with other species through competition, impacting growth. Nature regulates population growth through density-dependent and density-independent factors, which affect growth rate and mortality, regardless of population density. Conservation biologists study these factors to manage populations effectively and prevent extinction or overpopulation. Density-dependent Regulation - Most density-dependent factors are biological biotic and include predation, inter- and intraspecific competition, accumulation of waste, and diseases such as those caused by parasites -.Higher population density leads to increased mortality rates - A study on the giant intestinal roundworm showed that denser populations had lower fecundity, with fewer eggs - One theory suggested smaller females in denser populations produced fewer eggs due to limited resources, but a 2009 study disproved this - The reason behind the density-dependence of fecundity in this parasite remains unknown and requires more research - Density-dependent factors are typically biological and are known as biotic factors - Examples of density-dependent factors include predation, parasitism, herbivory, competition, and the accumulation of waste - These factors generally increase in impact as a population becomes more dense, leading to higher mortality rates - As a population grows, predators can more effectively hunt their prey - Low prey density can increase predator mortality - Parasites spread more easily in high population densities, causing severe epidemics in cities. - Cities historically relied on continual immigration to maintain population due to disease outbreaks.s - The development of sanitation and public health measures helped cities avoid sharp population declines from epidemics.cs - The plague in Europe during the fourteenth century caused a significant population decline  - Strip cropping(planting and growing alternating strips of erosion-resistant crops with strips of erosion-prone annual crops) can help control pests by preventing the spread of herbivores or plant pathogens among dense plant populations. - In 1980, southern New England experienced a gypsy moth infestation, leading to defoliation of forests due to competition for food, causing a sharp drop in population. - Various physical or chemical factors, such as weather, natural disasters, and pollution, can affect the mortality of a population regardless of its density.y - For example, a deer in a forest fire has the same chance of survival whether there are many other deer around or not. - Abiotic factors not only restrict population growth but can also decrease populations significantly below their previous level.s - These are known as density-independent factors as they impact the population regardless of size when the catastrophe strik.es - Population regulation in real-life situations is complex, with density-dependent and independent factors interacting - A dense population reduced by environmental factors will recover differently than a sparse population. - For instance, deer populations recover faster from harsh winters if more deer remain to reproduce.e Island populations - The smaller an island, the smaller the population of species on it (greater risk of extinction.on Terrestrial Ecology - Species diversity: the number of different species it contains (species richness) combined with the abundance of individuals within each of those species (species evenness) - Niche: - The total way of life or role of a species in an ecosystem. - All the physical, chemical, and biological conditions a species needs to live & reproduce in an ecosystem. - A common-property resource is a resource that is owned by no one but free to all, mostly renewal. - Biomass - The organic matter produced by plants; is dry weight. - Energy from wood, garbage & agricultural waste. - Ecological efficiency: percentage of useable energy transferred as biomass from one trophic level to the next. - Population control: the act of limiting the size of an animal population so that it remains manageable - Resource partitioning: the division of resources to avoid interspecific competition for limited resources in an ecosystem - Limited Resources: A population can grow until competition for limited resources increases & the carrying capacity (C.C.) is reached. - Typical Phases - 1. The population overshoots the C.C. - 2. This is because of a reproductive time lag (the period required for the birth rate to fall & the death rate to rise).  - 3. The population has a dieback or crashes. - 4. The carrying capacity is reached. - Macronutrients: Chemicals organisms need in large numbers to live, grow, and reproduce. - Ex. carbon, oxygen, hydrogen, nitrogen - Micronutrients: These are needed in small or even trace amounts - Ex. sodium, zinc copper, chlorine, and iodine. Cyclic movement of chemicals Carbon Cycle - - Effects of Human Activities on Carbon Cycle - We alter the carbon cycle by adding excess CO2 to the atmosphere through: - Burning fossil fuels. - Clearing vegetation faster than it is replaced. Phosphorous Cycle  - Effects of Human Activities on the Phosphorous Cycle - We remove large amounts of phosphate from the earth to make fertilizer. - We reduce phosphorous in tropical soils by clearing forests. - We add excess phosphates to aquatic systems from the runoff of animal wastes and fertilizers. - Phosphorus - Bacteria are not as important in the phosphorus cycle as in the nitrogen cycle. - Phosphorus is not usually found in the atmosphere or a gas state only as dust. - The phosphorus cycle is slow and is usually found in rock formations and ocean sediments. - Phosphorus is found in fertilizers because most soil is deficient in it and plants need it. - Phosphorus is usually insoluble in water and is not found in most aquatic environments. Nitrogen Cycle - Effects of Human Activities on the Nitrogen Cycle - We alter the nitrogen cycle by: - Adding gases that contribute to acid rain. - Adding nitrous oxide to the atmosphere through farming practices can warm the atmosphere and deplete ozone. - Contaminating groundwater from nitrate ions in inorganic fertilizers. - Releasing nitrogen into the troposphere through deforestation. - Effects of Human Activities on the Nitrogen Cycle  - Human activities such as the production of fertilizers now fix more nitrogen than all natural sources combined. - Nitrogen Fixation - First step - Specialized bacteria convert gaseous nitrogen to ammonia for plants to use - Cyanobacteria or bacteria in plant roots help with this process - Nitrification - Ammonia is converted to nitrite, then to nitrate - Assimilation - Plant roots absorb ammonium and nitrate ions - These ions are used to create important molecules like DNA, amino acids, and proteins.s - Ammonification - Nitrogen in living organisms is converted by decomposing bacteria into simpler compounds like ammonia after its use. - Denitrification - Nitrate ions and nitrite ions are converted into nitrous oxide gas and nitrogen gas. This happens when a soil nutrient is reduced and released into the atmosphere as a gas. The Sulfur Cycle - Effects of Human Activities on the Sulfur Cycle - We add sulfur dioxide to the atmosphere by: - Burning coal and oil - Refining sulfur-containing petroleum. - Convert sulfur-containing metallic ores into free metals such as copper, lead, and zinc, releasing sulfur dioxide into the environment. Biodiversity - Def. The many forms of life found on the Earth. “Wildness”  - Genetic Diversity – the variety of genetic make-up w/in a single species Species Diversity – the variety of species in different habitats on the Earth - Importance: It gives us food, wood, energy, free recycling, purification & natural pest control. - Measurement: Genetic tests, count/release, and tagging. The Gaia Hypothesis: Is the Earth Alive? - Some believe that life on Earth can have an impact on its chemical cycles and other processes - The strong Gaia hypothesis: life controls the earth’s life-sustaining processes. - The weak Gaia hypothesis: life influences the earth’s life-sustaining processes. Biomes - The most important factors in a biome are temperature and precipitation. - Biomes tend to converge around latitude lines on the globe. Climate Reclamation -Returingin vegetation to an area taht has been mined or disturbed by human use -THis can be done by re-planting, cleaning up pollution, regulations(laws) or any other activity designed to “fix” a destroyed area Invasive Species -They displace native species -They lower biodiversity -They can adapt very quickly to local habitats -They contribute to habitat fragmentation -They can reproduce very quickly Types of Species -Navtive nonatie, indicator, keystone, and foundation species play different ecological roles in communities Native:those that normally live and thrive ina particular community Nonnative species:those that migrate, deliberately or accidentally introduced into a community Human Impacts on Terrestrial biomes -Human activities have damaged or disturbed more than half of the world’s terrestrial ecosystems -Humans have had a number of specific harmful effects on the world’s deserts, grasslands, forests, and mountains. Desert: -Large desert cities -soil destruction by off-road vehicles -Soil saliniztion from irrigation -Depletion of groundwater -land disturbance and pollution from mineral extraction Grasslands: -conversion to cropland -Release of CO2 to atmosphere from grassland burning -Overgrazing by livestock -Oil production and off-road vehicles in arctic tundra Forests: -Clearing for agriculture, livestock grazing, timber, and urban development -Conversion of diverse forests to tree plantations -Damage from off-road vehicles -Pollution of forest streams Mountains: -Griculture -Timber extraction -Mineral extraction -Hydroelectric dams and reservoirs -Increasing tourism -Urban air pollution -Increased ultraviolet radiation from oone depletion -Soil damage from off-road vechicles Succession –the process wher plants and animals of a particular area are replaced by other more complex species over time Primary vs. Secondary succession -Primary begins with a lifeles area where ther is no soil(ex. Bare rock) Soil formation begins with lichens or moss -Secondary begins in an area where the naturalcommunity has been disturbed, removed, or destroyed, but soil or bottom sediments remain. Biomes -The most important factors in a biome are temperature and precipitation -Biomes tend to converge around latitude lines on the globe Climate -weather is a local area’s short-term physical conditions such as temperature and precipitation -Climate is a region’s average weather conditions over a long time -Latitude and elevation help determine climate -Different climates lead to different communities of organisms, especially vegetation  -Biomies=large terrestrial regions characterized by similar climate, soil, plants, and animals -Each biome contains many exosystems whose communities have adapted to differences in climate, soil, and other environmental factors Types of biomes -Biome type is determined by precipitaiton, temperature and soil type Desert -The everportaion is grater than the precipitation(covers 30% of earth) Variations in annual temperature(red) and precipitation(blue) in tropical , temperate and cold deserts Forests -Foresets have enough precipitation to support stands of trees and are found in tropical, temperate, and polar regions Taiga(evergreen coniferous forest) -Just south of the tundra (northern part of North America), it covers 11% of earth’s land. Its winters are long, dry and cold. Some places have sunlight 6 to 8 hours a day. The summers are short and mild, with sunlight 19 hours a day MOuntain biomes(Taiga) -High-elevation islands of biodiversity -Often have snow covered peaks that reflect solar radiation and gradually release water to lower-elevation streams and ecosystems Evergreen Coniferous Forests -Consist mostly of conebearing evergreen trees that keep there needles year-round to help the trees survive long and cold winters Tropical Rainforest -Near the equator, has warm temperatures, high humidity and heavy rainfall -Have heavy rainfall and rich diversity of species -have year-round uniformity warm temperatures and high humidity Temperate Rain Forests -Coastal areas support huge cone-bearing evergreen trees such as redwood and Douglas fir in a cool moist environment Temperat Deciduous Forest -It has moderate temperatures, long, warm summers, sold winters and lots of rain. Trees include oaks, hickory, maple, and beech -Most of the trees survive winter by dropping their leaves, which decay and produce a nutrient-rich soil Grassland -The rainfall is erratic and fires are common, has shrubs that are good for grazing animals Savanna -The tropical and subtropical grassland -warm all year long with alternating wet and dry seasons Chaparral These are coastal areas -winters are mild adn wet, with summer eing long, hot, and dry -has a moderate climate but its dense thickets of spiny shrubs are subject to periodic fires Tmperate Grasslands -THe cold winters and hot dry summer have deep adn fertile soil atht make them ideal for growing crops and grazing cattle Tundra Cover 10% of earth’s land. Most of the yaer, these treeless plains are bitterly cold with ice and snow. Has 6 to 8 week summer with sunlight nearly 24 hours a day Polar Grasslands -covered with ice and snow except during a brief summer Intraspecific Competition -simultaneous demand between members of the same species Interspecific Competition -Simultaneous demand for resources between members of different species Law of Tolerance -if any factor exceeds the minimum or maximum tolerance of that organism or population, it will fail to thrive >Zone of Physiological Stress -Organisms Infrequent >Zone of Intolerance -No Organisms Present History of Environmental Disasters, Protection, and Legislation 1854 - Henry David Thoreau writes Walden, inspiring many to live simply and in harmony with nature 1864 - George Perkins Marsh publishes Man and Nature, described by some environmentalists as the fountainhead of the conservation movement. 1872 - Yellowstone becomes the nation's first National Park 1892 - John Muir founds Sierra Club to protect the Sierra Nevada 1905 - National Audubon Society formed  1949 - Aldo Leopold publishes A Sand County Almanac, in which he sets guidelines for the conservation movement and introduces the concept of a land ethic. 1962 - Rachel Carson writes Silent Spring, about the use of DDT as a pesticide and how it hurt bird species' eggs 1969 - Garrett Hardin writes Tragedy of the Commons, showing that although an area might not be abused by its users, without a true limit and caretakers its resources eventually are depleted 1970 - EPA Act passed by Nixon, creating the Environmental Protection Agency 1970 - Clean Air Act bans certain aerosols in the USA 1973 - Endangered Species Act Passed 1979 - Three Mile Island meltdown in Pennsylvania of nuclear reactor 1984 - Bhopal poisoning in India 1986 - Chernobyl incident in Ukraine 1987 - Montreal Protocol signed by Reagan and Thatcher - attacks CFC disruption of ozone layer 1989 - Exxon Valdez spill in Prince William Sound off Alaska dumps millions of gallons of crude oil 1997 - Kyoto Protocol in Japan confronts global warming, USA doesn't sign 2010 - BP oil spill in Gulf of Mexico, biggest oil spill in US history 2010 - The Cove, documentary, released, revealing the horrors of Japanese cetacean killing Where dN/dt is basically the change in population divided by change in time, and K being the carrying capacity, and r-max being the maximum growth rate (biotic potential of the organisms) (rmax is sometimes just r). N is population size.