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Lecture 22

BIOL 190 Lecture 22: Ecology 2

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BIOL 190
Angela Cox

If we study interactions between lobsters and other local species in Maine, what level of ecology are we studying? ● Communities Why might some of these penguins die? ● An important idea in our study of evolution is that the environmental impacts which individuals will survive and reproduce… and the environment constantly changes Evidence for Environmental Change ● Long term (slow change, millions of years) ○ Plate tectonics ● Short term (faster) ○ Succession Plate Tectonics ● Plate tectonics explains: ○ Why mesozoic reptiles in Ghana (West Africa) and Brazil look so similar ○ How marsupials were free to evolve in isolation in Australia Primary succession - starts with bare rock ******************* Secondary succession - response to a disturbance Human impact on the environment…. Geological time frame: climate cycles Global Climate Change Rising Temperatures ● 1991-2012 average temperatures compared with 1901-1960 average Bottom line- there is tremendous variation in the environment, and the environment changes over time Population Ecology How and why do populations change? ● Important to our study of evolution because populations evolve Population Ecology ● Population- a group of animals of the same species that live in the same general area ○ Populations must be defined ■ All the trout in one river, one part of a river, all rivers in the US ● Population ecology- study of factors affecting population ○ Size- number of individuals ○ Density- number of individuals per unit of area ○ Structure- how many individuals in each age group ○ Growth rate- how fast the population is growing Population density= size, the number of individuals Population growth rate ● How fast the size of a population increases ● Influenced by ○ Exponential growth rate of a species ○ Population limiting factors ○ Carrying capacity Exponential growth ● Maximum rate of annual growth (rmax) ○ Assumes no limits! ○ Characteristic for each species ○ Determined by: ■ Age at sexual maturity ■ # reproductive cycles per year ■ # offspring per cycle ■ % offspring that survive and reproduce Logistic growth ● Accounts for population limiting factor(s) Population Limiting factors ● Environmental factors that may affect reproductive success ○ Biotic ■ Infectious diseases ■ Predators ■ Pathogens ■ Competition ■ Parasites ● Abiotic ○ Flood, fi
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