ENVS 1308 Lecture 2: Evolution, Species Interactions, and Biological Communities

Vocabulary flashcards for ENVS 1308 Lecture 2 covering species interactions, competitive outcomes, population growth models, trophic dynamics, and life-history strategies.

Competitive Exclusion

An outcome of species interaction where two competitors share the same limiting resource with persistent overlap, leading to the local decline, displacement, or exclusion of the poorer competitor.

Resource Partitioning

The division of limited environmental resources by species across space, food, time, feeding depth, or habitat layers, allowing for coexistence through differentiated resource use.

Coevolution

Reciprocal evolutionary change occurring across interacting lineages, where evolutionary adaptations in one species directly influence natural selection and trait response in another.

Convergent Evolution

The process where independent lineages evolve similar phenotypic traits under similar selective pressures without requiring reciprocal evolutionary interactions.

Keystone Species

A species whose effect on community structure or ecosystem function is disproportionately large relative to its total abundance or biomass, revealed by the community consequences of its loss.

Trophic Cascade

An ecological process where indirect effects propagate across multiple trophic levels, driven by top-down or bottom-up initiating changes.

Ecosystem Engineer

An organism that physically modifies habitat or environmental conditions, defining a structural mechanism regardless of its population size or keystone status.

Top-Down Control

An ecological regulation direction where predator changes directly drive herbivore abundance or behavior, propagating further to alter producer levels.

Bottom-Up Control

An ecological regulation direction where producer or resource availability directly limits consumer performance and higher trophic level abundance.

Density-Dependent Limits

Population regulation factors whose intensity or likelihood increases as population density rises, including resource competition, disease transmission, predation, and territorial conflict.

Density-Independent Limits

Environmental factors that reduce population numbers regardless of population density, such as droughts, floods, freezes, wildfires, and catastrophic habitat destruction.

$r$-Selected Species

Organisms adapted to unstable environments that favor rapid growth, short life spans, early maturity, low investment per offspring, high reproductive output, and lower trophic position.

$K$-Selected Species

Organisms adapted to stable environments near carrying capacity ($K$) that favor slower growth, long life spans, late maturity, high parental care, and fewer, larger offspring.

Exponential Growth

Rapid population acceleration occurring under unlimited favorable conditions, represented mathematically as \n\frac{dN}{dt} = rN\n.

Logistic Growth

Population trajectory subject to negative feedback as population size ($N$) approaches carrying capacity ($K$), modeled mathematically as \n\frac{dN}{dt} = rN \frac{(K - N)}{K}\n.

Predation Population Lag

A coupled population feedback pattern wherein prey population peaks precede corresponding predator population peaks over time.