Population ecology & Community ecology

Ecology

the study of interactions between living things and the environment

Population

members of the same species living in the same place at the same time

Population ecology

the study of change in populations over time

Population size

the number of individuals within a population

Population density

the number of individuals per unit area or volume at a given time

Change in population size

(births + immigration) - (death + emigration)

Changes in population over time

change in population size (N) / change in T (B - D)

Per capita birth rate (b)

the average number of births per individual in a population over time

Per capita death rate (m)

the number of deaths per individual in a population over time

Per capita rate of increase (r)

the average growth rate per individual in a population 

r-inst

instantaneous growth rate 

r-max

the maximum rate at which populations can increase

Population growth models

evaluate differences to determine why populations change

Exponential growth model

growth rate increases over time in proportion to the size of the population 

Logistic growth model

growth rate decreases as the population approaches its maximum size 

r-selection

Species that produce many offspring with little / no parental care

k-selection

Species that produce a few offspring with high parental care

Community

 populations that live in the same place and interact with each other

Community ecology

studies interactions among members of a community and how they affect the ecology of the community 

Resource

anything from the environment that meets the needs of a species 

Ecological niches

the role of a species within the structure and function of a community 

Competition

when two or more individuals attempt to use the same resource

Negative/negative interaction

both species get hurt 

Infraspecific competition

competition between members of the same species

Interspecific competition

competition between members of different species 

Competitive exclusion

competition forces one species to stop competing with another species for the same resource 

Fundamental niche

species use resources that won't cause competition 

Realized niche

species use resources that they actually need 

Resource partitioning

competing species use different resources so they can coexist

Predation

the consumption of one species by another species

Positive/negative interaction

one species benefits and one species gets hurt  

Coevolution

evolution due to the interaction between competing species 

• Predator gets better at catching prey

• Prey gets better at avoiding predators

Aposematic coloration

warning camouflage

Cryptic coloration

blending camouflage

Mimicry

visual similarity of one species to another

Batesian mimicry

a defenseless species resembles a dangerous species

Mullerian mimicry

different species resemble each other

Symbiosis

a long-term relationship between two different species

Parasitism

positive/negative interaction

Mutualism

positive/positive interaction

Commensalism

positive/neutral interaction