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Transcript
ECOSYSTEM ORGANIZATION And POPULATIONS OVERVIEW Ecosystem Organization Ecology is the study of the interactions of organisms with one another and their physical environment. Ecosystem Organization Every organism has a habitat, where organism lives, and a niche, role or job of organism in the ecosystem. Ecosystem Organization The interactions of the organisms may be studied as populations, communities, ecosystems or the entire biosphere. Ecosystem Organization Organism is a single living thing. Ecosystem Organization Population is the number of individuals of the same species in the same place at the same time. Factors That Control Population Growth Populations don’t grow indefinitely because of Limiting Factors. The major limiting factors are FWSS: – Food – Water – Shelter – Space Other Factors That Control Population Growth Other Limiting Factors: Competition Predation Parasitism Crowding Natural disasters Disease What dynamics might be involved in predicting population growth? Population Size Population Growth Rate Carrying Capacity Limiting Factors Population Size Number of individuals in a population Growth occurs when the birthrate is greater than the death rate. Population Growth Curves Exponential growth: Population increases by a constant proportion per unit of time At this growth rate the population exhibits a Jshaped curve 70 60 50 40 Exponential 30 B 20 10 Lag 0 A 0 1 2 3 4 Time 5 6 Population Growth Curves At this growth rate the population exhibits an S-shaped curve. K (carrying capacity) = maximum population size that an environment can support 600 500 K carrying capacity K 400 Population Logistic growth: Population increases rapidly for a period of time, its growth begins to slow, and ultimately, growth stops. stabilization 300 200 100 exponential 0 lag 0 10 20 Time (in days) 30 Natural Selection and Populations Relate the five concepts of natural selection to Logistic Graph. Genetic variation Numbers increase Competition Survival of the fittest Descent with modification Event A Event B Event C Event D Ecosystem Organization Community is all of the different populations living in a given area and time. Biodiversity Number of different species living within an ecosystem. How Biodiversity Impacts Population Growth 6 forces that cause populations to evolve: Mutation – ultimate source of all variation Migration – movement of organisms from one population to another, creates gene flow. Nonrandom mating – when individuals prefer to mate with others of their own genotype, inbreeding is an example. Genetic drift – random change in response to their environment. Natural selection –Survival of the fittest. Extinction- species that have disappeared permanently. Ecosystem Organization Ecosystem is all of the communities (biotic) and all of the physical factors (abiotic) in an area. Biotic & Abiotic Factors Biotic = Living organisms Abiotic = Nonliving Include air, water, temperature, moisture, light, and soil. Ecosystem Organization Biosphere is all of the areas on Earth where organisms live. Energy Flow in Ecosystems Energy flows into the biological world from SUN, the ultimate source of all energy. Producers Producers are autotrophs… they can make their own food through photosynthesis or chemosynthesis Plants, some bacteria, and algae Consumers Eat other organisms to obtain energy; also known as heterotrophs Example: cows, humans… Decomposers Consume organic wastes (feces, urine,dead leaves or bodies) Receive energy from every other type Responsible for the final step in the food chain Example: Earthworms, maggots, fungi, and some bacteria