History of Ecology/Population Growth

natural history

description of nature (primarily taxonomy)

natural philosophy

discovering the laws of nature

Ernst Haeckel

created the term “ecology”

“ontogeny recapitulates phylogeny”

Alexander Humboldt

conceived “terrestrial physics” was the first to study relationship between organisms and their environment

Charles Darwin

highlighted the complexity of species interactions

Eugene Odum

father of ecosystem and modern ecology. created the unifying concept of the ecosystem

population

a group of interbreeding organisms of the same species living within the same area

demography

study of things that affect population growth

r

per capita rate of increase

λ

growth rate per unit of time

exponential growth

models that assume density-independent growth. J-shaped curve, unlimited resources

logistic growth

assumes density-dependent growth

time lags

delayed responses between an environmental change (cause) and the corresponding ecological effect

stochasticity

temporal variation due to unexpected events. Increases density-independent mortality

environmental stochasticity

temporary environmental fluctuations that led to changes in population growth rates

endogenous

internal density-dependence

exogenous

external density-independence

demographic stochasticity

within-individual variation in a population across years

Theta Logistic Model

modifies the logistic model by altering the shape of density dependent relationships

allee effects

positive density dependence; when populations have a minimum population size below which birth rates collapse or death rates are extremely high; affects small populations

population dynamics

changes in size and shape of populations due to survivorship and reproduction