De-Extinction Study Guide

Biological Species Concept

A definition that describes a species as a group of organisms that can interbreed and produce viable, fertile offspring.

Reproductive isolation

is a method of defining a species based on its ability to interbreed and produce viable, fertile offspring under natural conditions.

• Allopatric speciation

is the process of speciation that occurs when populations are geographically isolated from each other, leading to reproductive isolation and evolutionary divergence.

• Sympatric speciation

is the process of speciation that occurs within a shared habitat, often through mechanisms like polyploidy or behavioral changes that reduce gene flow.

• Prezygotic barriers

are mechanisms that prevent mating or fertilization between species before the formation of zygotes, thus contributing to reproductive isolation.

• Postzygotic barriers

are mechanisms that occur after fertilization, preventing the successful development or reproduction of hybrid offspring, thus also contributing to reproductive isolation.

• Adaptive radiation

is the rapid evolution of diversely adapted species from a common ancestor in response to varying environmental conditions.

Gradualism

a cautious, step-by-step approach to species reintroduction that emphasizes incremental change and careful monitoring to avoid ecological harm. 

• Punctuated equilibrium

a theory in evolution that says new species appear in relatively rapid bursts of change, separated by long periods of little to no change

Natural Selection

the process where organisms with traits better suited to their environment survive and reproduce more successfully than others

Selective pressure

any factor in the environment that affects an organism's ability to survive and reproduce

• Adaptation

developing features—anatomical, physiological, or behavioral—that increase the chances of survival and reproduction

• Evolutionary fitness

how good a particular genotype is at leaving offspring in the next generation relative to other genotypes

• Directional selection

a type of evolution where traits at both extremes of a spectrum are favored, while intermediate traits are selected against

• Stabilizing selection

a form of natural selection wherein individuals with moderate or average phenotypes are more fit

• Disruptive selection

a specific type of natural selection that actively selects against the intermediate in a population, favoring both extremes of the spectrum

• Genetic variation

the difference in DNA sequences among individuals within a population

• Genetic drift

the change in frequency of an existing gene variant in the population due to random chance

• Bottleneck effect

when a population's size is suddenly and drastically reduced due to a catastrophic event, which then limits the genetic diversity of the surviving population

• Founder effect

when a small group of individuals becomes isolated from a larger population and establishes a new one