Ecology

ecology

interaction between organisms and their environment factors affecting distribution and abundance

population

group of individuals living in particular place

populations are dynamic

abundance and distribution changes over time

population growth rate

(birthrate +immigration rate)-(death rate + emigration rate)

theory exponential growth

• assumes no limits to resources

• birthrate and death rate do not change

Reality Exponential growth

• growth is affected by abiotic and biotic factors that move impact on crowded populations

• birth rates and death rates do change at higher population sizes

limited resources have density dependent effect

• depends on size of population

• changes in birth and death rates

Carrying capacity

k, maximum population size environment can sustain, measure of resources, oscillate around K, k is not fixed

population is small

most resources are still available, exponential growth

population at k

no unused resources are available, growth will decrease

ecology of communities

how do other organisms interact within a communities, multiple populations living in an environment and their interactions

food chains and food webs

• follow the flow of energy in a system

• food webs dont fallow the trophic laws well

trophic levels

functional position organisms occupy in a food chain

commensalism

relationship between 2 species where 1 organism benefits while the other is neither helped nor harmed

mutualism

both are helped

predator prey

animals consuming others for food

parasites

where 1 organism benefits by living on or inside another organism causing it harm

effects of competition

no one gains and leads extinction

symbiosis

any type of a close and long term biological interaction between two different biological organisms be it mutualistic, communalistic, or parasitic

long term effects of competition

• extinction of 1 species from area where both species occur

• niche = all the resources used by an organism

• 1 will used the resources more efficiently

• less efficient species will go extinct

evolution of adaptations that reduce competition

behavioral adaptatopns

specialist species evolve

each species use different resources

ecology of ecosystems

study of nutrient and energy flows through living and nonliving components

biogeochemical cycles

nutrients more between inorganic (soil, rock) components and biological components

4 reservoirs of carbon

• atmosphere

• terrestrial biosphere

• geological

• oceans

energy flow

light energy, chemical energy, heat energy

what limits trophic levels

• highest trophic small amounts of energy

• less energy supports fewer individuals

energy and population size

species at top levels are rare

• specialist species are also rare