Transcript Populations
Populations Ms. Lowrie Science 10 Definitions Community Ecosystem Habitat Population Species We will correct them in another order! Ecosystem A group of communities that share a physical environment Including air, land, water, living organisms Species A group of organisms that can reproduce only among themselves Habitat Characteristics of the environment where an organism lives Ex: A giraffe’s habitat is the African savannah Population A group of individuals of the same species living in the same area Ex: A population of giraffes in eastern Africa OR a population of giraffes in southern Africa Community Includes all populations of organisms in an area Ex: A community of giraffe, elephant, lion, tiger, insect and plant populations How they all connect: Species Populations How did the killer whale’s feeding habits affect the sea otter? Food Chains (#1, a-c) Draw the ocean food chain (before). Draw the kelp food chain (after). How are the two food chains mentioned in (a) and (b) different? Killer whale Seals Sea Lions Fish (perch & herring) Ducks Sea Gulls Sea Stars Kelp Food Web (d) Sea Otters Sea Urchins Eagles Mussels Killer whale Seals Sea Lions Fish (perch & herring) Kelp Food Web (simple) Sea Otters Sea Urchins Populations (#1, e-g) e. Why did killer whales change their feeding habits? f. What effects did these changes have on the ocean ecosystem? g. What effects did these changes have on the kelp ecosystem? Killer whale Seals Sea Lions Fish (perch & herring) Food Web (#1, f) Populations (e-g) e. Why did killer whales change their feeding habits? f. What effects did these changes have on the ocean ecosystem? g. What effects did these changes have on the kelp ecosystem? Killer whale Sea Otters Sea Urchins Kelp Food Web (#1, g) Populations 2. Explain how each organism survives in a food web. 3. Outline how the population size in each trophic level (feeding level) is continually adjusted or changing. Carrying Capacity Maximum amount of individuals that an environment can support Example: Paramecia Carrying Capacity 4 Factors that affect: Materials & Energy Food chains Competition Density Factor: Materials & Energy Populations are limited by the amount of abiotic factors available Such as: sunlight, water, oxygen, etc. E.g. Too little sunlight reduces plant growth Factor: Materials & Energy Another example: Layer of algae on pond blocks sunlight from reaching organisms at bottom of pond Factor: Food Chains Availability of food If organisms in one trophic level are affected it will affect organisms in other trophic levels E.g. Killer whales & seaotters Factor: Competition Due to the demand for resources Such as: food, water, mates, space, etc. Types of Competition Intraspecific Between individuals of same species Types of Competition Interspecific Between individuals from different species Factor: Density More organisms in a space makes it more difficult to survive Population Density Number of organisms that can live in an area Population Density Based on an organism’s need for space E.g. Bears & elk need more space than some birds Factors that Limit Population Growth Density-Dependent Factors Any factor that affects growth that DEPENDS on the number of individuals in a population Examples? Factors that Limit Population Growth Density-Dependent Factors E.g. competition, disease, parasites, predation, overcrowding (leads to: stress, offspring neglect, aggression), etc. Factors that Limit Population Growth Density-Independent Factors Any factor that affects growth that DOES NOT depend on the number of individuals in a population Examples? Factors that Limit Population Growth Density-Independent Factors E.g. extreme weather, earthquake, volcanic eruption, forest fire, flood, drought, pollution, etc. Check Your Understanding A. How might overcrowding lead to a reduction in population size? B. How might an increase in the population of hawks in an area lead to an increase in the population of plants? Explain the graph: Any Questions???