Ecology: Populations

What is ecology?

the study of how organisms interact with their environments

What are the levels of organization?

biosphere, ecosystem, community, population, species

Biosphere:

portion of the earth that supports life

ecosystem:

community + abiotic factors

population:

a group of interacting individuals of the same species occupying a specific area

species:

group of organisms that can reproduce

what is population?

science that deals with measuring changes in population size and composition

methods of determining population size?

1. directly count

2. sampling

3. capture, mark, recapture

sampling:

count small area extrapolate to a large area

Capture- recapture method:

• mark the animal

• release them in the wild

assumptions in capture- recapture

• marking has no effect on mortality

• marking has no effect on likelihood to being captured

• there is no immigration or emigration between sampling times

what are the 3-population distribution?

clumped, nearly uniform, random

Clumped distribution:

• most common in plants and animals

• protection, resources

uniform:

may result from direct interactions between individuals in the population

random pattern:

the individuals in a population are spaced in an unpredictable way

2 types of growth curves?

• exponential growth

• logistic growth

exponential growth:

• ideal conditions

• no limiting factors

• constant growth rate

• j shaped curve

logistic growth:

• limiting factors present

• falling growth rate

• s shaped curve

• resources become less available