Ecology Unit 1.2 PDF

1.2 Interdependence Interdependence ▪ No species can survive by itself. ▪ Each species is dependent on many other species in its ecosystem in order to survive and prosper. ▪ Coevolution: the evolution of two or more species that interact with each other in a mutually dependent way ▪ E...

1.2 Interdependence Interdependence ▪ No species can survive by itself. ▪ Each species is dependent on many other species in its ecosystem in order to survive and prosper. ▪ Coevolution: the evolution of two or more species that interact with each other in a mutually dependent way ▪ Ex. predators and prey may reciprocally affect each other’s evolution through the process of natural selection Food Chains/Webs/Pyramids ▪ Food chains and food webs, which represent different types of ongoing relationships between and among all the organisms, within a particular environment. They show interdependence. ▪ Food chain: a model that shows the linear pathways through which food is transferred from producer to primary consumer to higher trophic levels. ▪ Energy relationships in a real ecosystem are too complex to be illustrated by a single food chain. Most consumers eat a variety of foods, and more than one consumer species will eat the same species of organisms. A food web represents many cross-linked food chains. ▪ Nutrients and energy move from producers to consumers ▪ Energy flows in one direction through the community and eventually leaves therefore, a continuous source of energy is required. ▪ Nutrients are recycled through a process called biodegradation. Biogeochemical cycles refer to nutrient cycles. There is an oxygen cycle, water cycle, carbon cycle, phosphate cycle etc. ▪ Animals breathe in oxygen and release carbon dioxide during respiration. Plants consume carbon dioxide and release oxygen during photosynthesis. ▪ Water cycles through the atmosphere, oceans, ground water, surface water, and organisms. Water precipitates from the atmosphere into ecosystems, flows through them, and evaporates back into the atmosphere. ▪ Phosphate is taken from the soil by the roots of plants. Animals eat plants. The phosphate is released via animal feces or decomposition after death, and is absorbed back into the soil. ▪  Food Chains/Webs/Pyramids ▪ Producers ▪ autotrophic organisms that provide food to other organisms in ecosystems Ex. plants, algae ▪ autotrophs: “self-feeders”, make their own food ▪ photosynthetic - use sunlight (energy from the Sun) Ex. phytoplankton (microscopic algae), ENERGY FLOW algae, almost all plants ▪ chemosynthetic- use chemicals Ex. organisms that live on the ocean floor or in caves where there is a total absence of light use the thermal and chemical energy from Earth’s interior instead of sunlight  Food Chains/Webs/Pyramids ▪ Consumers ▪ heterotroph: “other feeders”; consume other organisms or biotic waste to survive ENERGY FLOW ▪ Primary consumer- usually herbivores who consume only producers Ex. grazing animals, small animals and insects, zooplankton (eat phytoplankton) ▪ Secondary consumer - consume primary consumers; include omnivores (consume producers and small consumers), scavengers (consume pros and cons from others’ kill), carnivores (only consume consumers) Ex. racoons, humans ▪ Tertiary consumer- consume secondary consumers; often predators and top of the food chain (apex predator); carnivore Ex. cougar, tiger, shark ▪ Decomposers ▪ Consume dead organisms or absorb some of their nutrients themselves but return other nutrients to the soil to be used by producers Ex. bacteria and fungi ▪ Type of decomposer, detritivores -consume detritus (waste material) such as the bodies of other organisms, plant debris, and animal feces ▪ A high number of decomposers is linked to rich fertile soils. A low number of decomposers results in little decay and the soil is thin and low in nutrients. ▪ Very important for recycling nutrients (biodegradation is the process that makes nutrients contained in waste and dead matter available to producers by breaking down organic matter or substances into simpler substances)  Food Chains/Webs/Pyramids Food Chains Top carnivore (apex predator) is at the highest trophic level, has no natural predator and its body will eventually decompose Producer Primary Secondary Tertiary Consumer Consumer Consumer Trophic Trophic Trophic Trophic Level Level Level Level 1 2 3 4 The arrows indicate that the first organism is food for the next. Trophic level = feeding level; the position of an organism in relation to the order of nutrient and energy transfers in an ecosystem **Decomposers are at all trophic levels because they consume material from all trophic levels  Food Chains/Webs/Pyramids Ecological Pyramid or Food Web Food Pyramid (Pyramid of Energy) The pyramid of energy is always a pyramid shape. The energy at each level is presented by the size of the box. Producers are at the bottom and successively higher trophic levels are on top. ~10% of energy from one level gets passed to the next (90% remains in the level to be used for basic life processes of the organisms at that level (ex. movement, reproduction, and maintaining body temperature) or is lost as heat) The low rate of energy transfer limits the number of trophic levels (rarely more than 4 trophic levels)  Food Chains/Webs/Pyramids ▪ Other types of ecological pyramids exist too. ▪ Pyramid of biomass ▪ Biomass: dry mass of living, or once living, organisms per unit area ▪ Can be pyramid shaped or inverted ▪ Inverted shapes can occur when a small biomass of producers (ex. algae) supports a large biomass of herbivores (ex. fish). The algae reproduce quickly and can replenish the numbers consumed by herbivores. ▪ Pyramid of numbers ▪ Represents the actual number of organisms at each trophic level ▪ Shape can be inverted or pyramid shaped. ▪ Ex. Grasslands have very large numbers of small producers whereas a forest of similar size may only contain a few trees. A single tree may support a large number of insects. Predator-Prey Interaction (Predation) ▪ Predator-prey interactions (predation), where one organism (the predator) captures and eats the other organism (the prey). ▪ Creates a predator-prey cycle ▪ Cyclic rise and fall in both populations ▪ Prey population decreases as the predators eat the prey. ▪ The predator population decreases as the available prey (food) runs out. ▪ The decreased number of predators allows more prey to survive and the prey population rebounds. ▪ The predator population now increases as it has an abundant food supply. ▪ Predators reduce the size of the prey population, preventing the prey from outstripping their food supply, resulting in starvation for the prey population. ▪ Predators tend to capture the old, sick, or weak members of the prey population, thus the healthy and strong members of the prey population survive to reproduce, producing healthy strong offspring. ▪ Shows interdependence. ▪ Example ▪ Great white shark eating a seal ▪ Mountain lion captures, kills, and eats deer Predator-Prey Interaction (Predation) Canadian lynx (predator) Time lag =the delay as the consumes snowshoe hare (prey) predator population responds to the changes in the prey population Symbiosis ▪ This is where two or more organisms live on or in close proximity to one another and share a close relationship ▪ Can be another type of interdependence where there is an association between members of different species ▪ “Symbiosis” means “living together” ▪ There are different types of symbiotic relationships. The 3 main types include: ▪ Commensalism ▪ Mutualism ▪ Parasitism Commensalism ▪ This is a relationship in which one of the participating members benefits, but the other does not. However, there is no harm done to the second organism. ▪ +/ (one benefits and other is unaffected) ▪ Examples ▪ a bird using a tree to build its nest but doesn’t affect the tree ▪ barnacles on a whale receive transportation but don’t affect the whales ▪ flowering orchids live on tree trunks but don’t affect the tree ▪ the clown fish gets protection from predators by swimming around the stinging tentacles of the sea anemone but the sea anemone isn’t affected Mutualism ▪ This is a relationship in which both organisms benefit from the relationship. ▪ ++ (both benefit) ▪ Examples ▪ lichen (algae and fungi) growing in the Arctic Tundra ▪ Algae produces food for both ▪ Fungi protects algae from dehydration ▪ the flower Clusia provides medicine (antibiotic) to bees and the bee pollinates the flower Parasitism ▪ This is a relationship in which one organism benefits while the other organism (the victim) is harmed. ▪ The parasite meets it needs at the expense of the host ▪ Usually, the parasite doesn’t kill the host because the host represents the parasite’s food supply. ▪ Usually one organism lives on/in another organism and feeds on it. ▪ Not limited to two organisms. ▪ + - (one benefits and other is harmed) ▪ Examples ▪ the tapeworm in a human host absorbs nutrients and harms host because they don’t get the nutrients they need ▪ the Mexican bean beetle in a plant eats the leaves of the plant and harms host ▪ leeches on a human host get blood from the human and harms host ▪ lice which live and feed on the body of their host  Parasite Video Symbiotic Relationships ▪ There are many examples of these types of symbiotic relationships, which show the importance of adaptations, helping particular species survive. Competition ▪ Competition happens when two or more species need the same limited resource. It is created between organisms when their niches overlap. ▪ There are two types of competition. ▪ Interspecific competition (interspecies competition) ▪ Competition for limited resources between members of two or more different species ▪ Examples ▪ lions and elephants at the same watering hole ▪ plants competing for light ▪ Intraspecific competition (intraspecies competition) ▪ Competition for limited resources among members of the same species ▪ Example ▪ Competition for mates ▪ There is one type of interaction species in which neither species benefits. ▪ Competition helps to limit the population sizes of the competing species. ▪ When there’s competition, populations tend to become more specialized and this may lead to something called resource partitioning.  Niche ▪ Regardless of what relationship an organism has with others, they all play a role within an ecosystem. ▪ As biotic and abiotic factors interact, ecological niches for each species develop. ▪ A species’ adaptations are like its superpowers/characteristics that allow it to succeed or flourish in its ecological niche, and thus usually go hand-in-hand with its niche ▪ A niche is the role of an organism within a particular ecosystem. ▪ An organism’s niche includes: ▪ What it eats ▪ What eats it ▪ How and when it reproduces ▪ Its habitat ▪ Nesting site, range and habits ▪ What effect it has on the other populations (ex. What it competes with for food, mates etc.) ▪ What effect it has on the environment/the habitat ▪ What limits of environmental change it can tolerate (broad or narrow)  Niche ▪ The niche occupied by a population in one area may not be the same as that in a different area because the food supply and competitors may be different. ▪ In addition, the niche occupied by a species may change throughout its lifetime. ▪ Organisms also interact in their food chains and take on different niches depending on their place in the food chain. ▪ Example ▪ the frog changes its environment and what it eats as it matures ▪ fish evolved gills because gills help it succeed in its aquatic ecological niche Example Black Bear’s Niche Black bear’s niche includes: ○ occupying the understory of dense forest areas ○ eating berries, nuts, shoots & buds (controls the spread of those plants) ○ eating fish and larger mammals ○ helping make game trails ○ providing food for scavengers Video Niche The ecological niche demonstrates the range of environmental change that a species can tolerate and thrive in. This limit is called the range of tolerance of a species. ○ The range of tolerance determines if an ecological niche is broad or narrow. Broad Niche Some organisms are generalists and have a broad niche. ○ This means they can survive under many different environmental conditions, eat a large variety of food and are spread over large areas. Thus they do not have specific needs/requirements. ○ Flexible and able to withstand a great deal of change ○ High range of tolerance ○ Examples Racoons can eat anything and live in all kinds of climates Dandelions tolerate all kinds of climate fluctuations Others- cockroaches, mice, squirrels, rats, bobcats, coyotes *very tolerant to changes Narrow Niche Some organisms are specialists and have a narrow niche. ○ This means they use a few or only one dependable food source and can’t spread over large areas. This the species lives within a very limited (low number) of conditions with very specific needs/requirements ○ Specific and not able to withstand much change ○ Low range of tolerance ○ Examples Koalas only eat (able to digest) eucalyptus tree leaves (often have a threatened status) Pandas only eat bamboo’ Others- Canada lynx *Can’t survive on anything else and very sensitive to environmental changes *In the tropics, temperature and food supplies are relatively stable, therefore most organisms there are specialists, which means they have adaptations that make them very efficient at surviving in their own environments. This specialization allows many different species to inhabit a single area, and prevents any one species from spreading over too large of an area. Many adaptations that make a species successful in one niche may prevent it from inhabiting other environments - “trap of specialization.” Resource Partitioning ▪ Resource partitioning is a method for similar species to coexist in the same area. ▪ The division of resources among two or more coexisting species causes each species to have a slightly different niche. There is still some overlap between species but not enough to cause the species to compete directly for resources. ▪ Examples ▪ different species may eat from different parts of the tree ▪ different species may share an area based on their nesting preference or heat tolerance. Assignment ▪ Read textbook pages: ▪ Focus: 16-25 ▪ Science in Action: 14-19 ▪ 1.2 Worksheet Assignment 1. List three different types of interdependence among living organisms. Provide an example of each. 2. How does the prey population benefit when individuals in this population are eaten by a predator? 3. Classify the following symbiotic relationships. Create a chart to record your data, use the coding “+” to represent a benefit, “–” to represent harm, and “n” to represent no benefit or harm. How would you use this coding to represent each organism involved in the following relationships? Explain your answer. a) mutualism b) parasitism c) commensalism 1. A student observes the following organisms in a 30 cm2 section of the front lawn of your school: a dandelion; a small butterfly on the flower of the dandelion; a caterpillar eating the leaves of the dandelion; and a worm in the soil. Describe the niche of each organism.