Unit 2: De-Extinction Study Guide Speciation Quiz

Biological Species Concept

Defines a species as a group of organisms that can interbreed and produce fertile offspring, but are reproductively isolated from other groups.

Reproductive isolation

When populations cannot successfully interbreed due to physical, behavioral, or genetic barriers.

Allopatric speciation

Formation of new species when populations are geographically separated.

Sympatric speciation:

Formation of new species within the same geographic area, often due to ecological or behavioral differences.

Prezygotic barriers

Prevent fertilization (e.g., mating behaviors, physical incompatibility, temporal isolation).

Postzygotic barriers 

Occur after fertilization, leading to infertile or nonviable offspring (e.g., mule sterility).

Adaptive radiation

Rapid diversification of a species into multiple new forms to exploit different ecological niches.

Gradualism

Evolutionary change occurs slowly and steadily over long periods.

Punctuated equilibrium

Long periods of little change interrupted by short bursts of rapid evolution.

Natural Selection

Process where individuals with advantageous traits survive and reproduce more successfully.

Selective pressure

Environmental factors that influence which traits are favorable (e.g., predators, climate).

Adaptation

A heritable trait that increases an organism’s survival or reproductive success.

Evolutionary fitness

An organism’s ability to survive and reproduce, passing on its genes.

Directional selection

Favors one extreme phenotype (e.g., giraffes with longer necks).

Stabilizing selection

Favors intermediate traits, reducing variation (e.g., human birth weight).

Disruptive selection

Favors both extremes over intermediate traits (e.g., very light and very dark mice in a patchy environment).

Sexual selection

Traits that improve mating success, even if they reduce survival (e.g., peacock feathers).

Genetic variation

Differences in DNA among individuals in a population, providing raw material for evolution.

Genetic drift

Random changes in allele frequencies, especially in small populations.

Bottleneck effect

Sharp reduction in population size due to events like disasters, reducing genetic diversity.

Founder effect

a genetic phenomenon where a new population is established by a small number of individuals from a larger population, resulting in a loss of genetic diversity and a different frequency of certain alleles than the original population

Explain the processes and mechanisms that drive speciation and describe the conditions that may lead to new species

Speciation is the evolutionary process by which populations diverge to form new species, driven by mechanisms that reduce or eliminate gene flow between groups. It occurs when reproductive isolation develops, preventing interbreeding, and is shaped by environmental, genetic, and behavioral factors

Predict the rate of evolution and speciation under different ecological conditions

The rate of evolution and speciation varies widely depending on ecological conditions: stable environments tend to slow evolutionary change, while dynamic or stressful environments accelerate divergence and the formation of new species.

Explain how genetic diversity in a population affects its ability to withstand environmental pressures

Genetic diversity strengthens a population’s ability to survive environmental pressures because it provides the raw material for adaptation. Populations with high genetic variation are more resilient to challenges like climate change, disease, and habitat loss, while low diversity increases vulnerability to extinction.