Key Concepts in Evolution and Natural Selection

Evolution

Any change in the inherited traits of a population that occurs from one generation to the next

Natural Selection

The process where organisms adapted to their environment tend to survive and produce more offspring

Adaptation

The biological mechanism by which organisms can adjust to new environments or to changes in their current environment

Adaptive Radiation

A single species evolves into an array of descendants that differ greatly in form and/or behavior

Key Innovation

A newly evolved trait in a species that allows members to use resources or other aspects of the environment that were previously inaccessible

Character Displacement

When natural selection favors individuals in a species that use resources not used by other species

Population

Smallest unit for evolution

Punctuated Equilibrium

Species experience long periods of little to no evolutionary change punctuated by bursts of change

Divergent Evolution

The process where a group from a common ancestor evolve and accumulate differences, resulting in the formation of new species or subspecies

Convergent Evolution

Organisms look similar due to similar habitats or environments

Stabilizing Selection

Favors middle phenotypes (reduces the amount of variation in a trait by favoring the average)

Directional Selection

Favors extreme phenotypes (changes average value)

Disruptive Selection

Favors one or more different phenotypes (increases amount of variation)

Oscillating Selection

Fluctuates based on the environment

Anisogamy

Differential investment in reproduction between males and females

Sexual Dimorphism

Differences in secondary characteristics (male cardinals have red feathers and females have brown feathers)

Ornaments

Attractive traits that increase mating success

Armaments

Weaponry used to outcompete other individuals

Monogamy

One male with one female

Polygyny

Males mate with multiple females

Polyandry

Females mate with multiple males