Ecology - Populations

Ecology

The study of how organisms interact with their environment

Habitat

The location where a population lives

Individual

One single organism

Population

A group of individuals that belong to the same species and live in the same area

Community

All the different populations that live and interact together in an area

Ecosystem

A community of organisms and their abiotic environment

Biosphere

Part of Earth in which life exists including land, water, and air or atmosphere

Populations are described by their

Distribution and abundance

Random Population Distribution

Haphazardly located individuals, with no pattern (Ex. Trees)

Clumped Population Distribution

Individuals living in large groups for better food, water, and protection (Ex. Elephants)

Uniform Population Distribution

Individuals are evenly spaced since they are competing for a limited resource (Ex. Penguins, Redwood Trees)

Populations can either optimize __ or __.

Survival or Fecundity

Fecundity

Reproductive potential

Fitness Trade-off

The process through which a trait increases in fitness at the expense of decreased fitness in another trait (fitness cost)

Fitness

Ability of an organism to survive and reproduce in its environment

Fitness Trade-Offs

Lead to different life strategies

Fitness Type 1

Maximize longevity and survivorship, with fewer offspring (Ex. Humans)

Fitness Type 2

Same probability of dying each year (Ex. Songbird)

Fitness Type 3

Short life span and high death rate for seedling/larvae, produce large number of offspring (Ex. Most fish, rabbits, mice)

Life History

How individuals allocate resources for growth, reproduction, and survivorship

Can life history change in a species?

Yes, life history in species can change depending on the environment of the individual. This is NOT evolution, just different traits are expressed

Population growth is

Exponential

Density-Dependent Factors

Limit population size by altering birth and death rates (Ex. Competing for resources)

Density-Independent Factors

Mainly abiotic factors that affect population (Ex. Temperature, Natural Disaster)

Predation increases as

Prey populations increase

Carrying Capacity

Largest number of individuals of a population that a environment can support

Logistic Growth Equation

Populations grow exponentially, and the growth rate decreases as you approach carrying capacity

Can carrying capacity change?

Yes, depending on the amount of resources in an environment at a particular time.

Population overshoot

Population growth above carrying capacity