Ecology & Evolution Flashcards

Vocabulary flashcards for Ecology and Evolution unit.

Ecology

The study of interactions among living things (biotic factors), and between biotic factors and their environment (abiotic factors)

Ecosystem

A geographic area where biotic and abiotic factors interact.

Community

Two or more populations of different species occupying the same geographic area at the same time.

Population

A group of organisms that belong to the same species and live in a particular place at the same time.

Population Density

How crowded a population is. The number of individuals per unit area or volume.

Population Size

The number of individuals a population contains.

Population distribution

The location of individuals relative to one another.

Exponential Growth Rate

The accelerating increase that occurs during a time when growth is unregulated (an abundance of resources and no predators)

Logistic Growth Model

Growth rate decreases the larger the population becomes and eventually stabilizes it.

Carrying Capacity

The maximum population that a given area can sustain

Evolution

Change in a population over time

Fitness

Individuals in a population with more successful adaptations survive and reproduce more and pass on their traits to their offspring

Adaptation

A trait that allows an organism to survive better in the environment

Natural Selection

A mechanism to account for changes in a species: Natural Selection

Directional Selection

This type of selection shifts the overall makeup of the population by acting against individuals at one of the phenotypic extremes.

Stabilizing Selection

Occurs when the environment favors intermediate phenotypes

Disruptive Selection

Typically occurs when environmental conditions vary in a way that favors individuals at both ends of a phenotypic range over individuals with intermediate phenotypes.

Genetic Equilibrium

A condition in which the allele frequencies and genotype frequencies in a population do not change over time. Meaning, evolution does not occur.

Genetic Drift

It is a change in allele frequencies due to random events

Bottleneck Effect

A random catastrophe kills off most of a population and only a few random individuals survive.

Founder Effect

A loss of genetic diversity when a small group of individuals establish a new population

Gene Flow

The migration of individuals between populations (immigration and emigration)

Sexual selection

A type of selection that acts on an organism’s ability to obtain (by any means necessary) and reproduce with a mate.

Species

A group of organisms that can interbreed with one another and produce fertile offspring.

Allopatric Speciation

Organisms become geographically isolated.

Sympatric Speciation

Organisms live in the same area, but become reproductively isolated due to behaviors etc.

Habitat isolation

Lack of opportunities to encounter each other.

Temporal isolation

Breeding at different times or seasons.

Behavioral isolation

Different courtship rituals.

Gametic isolation

Molecular incompatibility of eggs and sperm or pollen and stigma.

Reduced hybrid fertility

Vigorous hybrids that cannot produce viable offspring.

Microevolution

The change in allele frequencies in a population; can be observed over short periods of time

Macroevolution

Patterns of evolution above the species level that occur over long periods of time

Adaptive Radiation

Many new species derive from a single species; can occur after individuals colonize a new environment that has a variety of different habitats with few or no competitors.

Coevolution

Joint evolution of two closely interacting species; each is a selective agent for traits of the other; each adapts to changes in the other

Predation

Members of one species (predator) capture kill, and feed on another species (prey)

Parasitism

One organism (parasite) lives on part of another organism (host)

Mutualism

Two species interact in a way that benefits both

Commensalism

One organism benefits from another, but neither helps nor harm that other organism

Interspecific Competition

One species gains more resources (space, food, etc) than the other species.

Biodiversity

Is a measure of variation at the genetic, species, and ecosystem levels.

Keystone species

A species that has a disproportionately large effect on community structure; are often top predators

Homologous Structures

Parts of different organisms, that may look dissimilar, but that developed from the same ancestral body parts

Analogous structures

Body parts that look alike in different groups of organisms (and often have similar functions) but evolved independently

Vestigial Structures

Organs, structures, or parts that are incomplete or have no apparent function -- remaining parts of once functioning organs.