Evolution and Natural Selection Vocabulary

Flashcards covering vocabulary terms related to evolution, natural selection, and speciation.

Natural Selection

A process in which individuals that have certain traits tend to survive and reproduce at higher rates than other individuals because of those traits.

Evolution

Change in the genetic makeup of a population over time; descent with modification.

Adaptations

Inherited characteristics of organisms that enhance their survival and reproduction.

Artificial selection

The selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits.

Gene pool

A population's genetic makeup, consisting of all copies of every type of allele.

Microevolution

Small scale genetic changes in a population.

Genetic drift

Chance events that cause a change in allele frequency from one generation to the next.

Bottleneck effect

When a large population is drastically reduced by a non-selective disaster.

Founder effect

When a few individuals become isolated from a large population and establish a new small population with a gene pool that differs from the large population.

Gene flow

The transfer of alleles into or out of a population due to fertile individuals or gametes.

Relative fitness

The number of surviving offspring that an individual produces compared to the number left by others in the population.

Directional selection

Selection towards one extreme phenotype.

Stabilizing selection

Selection towards the mean and against the extreme phenotypes.

Disruptive selection

Selection against the mean; both phenotypic extremes have the highest relative fitness.

Sexual selection

A type of natural selection that explains why many species have unique/showy traits.

Hardy Weinberg Equilibrium

A model used to assess whether natural selection or other factors are causing evolution at a particular locus.

Systematics

Classification of organisms and determining their evolutionary relationships.

Taxonomy

Naming and classifying species.

Phylogenetics

Hypothesis of evolutionary history using phylogenetic trees to show evolution.

Phylogenetic trees

Diagrams that represent the evolutionary history of a group of organisms.

Cladograms

Diagrams where each line represents a lineage and each branching point is a node representing common ancestors.

Synapomorphy

A derived character shared by clade members.

Parsimony

The principle of using the hypothesis that requires the fewest assumptions when there are conflicting characters.

Outgroup

A lineage that is the least closely related to the rest of the organisms in a cladogram or phylogenetic tree.

Monophyletic group

Includes the most recent common ancestor of the group and all of its descendants.

Paraphyletic group

Includes the most recent common ancestor of the group, but not all its descendants.

Polyphyletic group

Does not include the most recent common ancestor of all members of the group.

Speciation

Formation of new species.

Allopatric speciation

Physical barrier divides population or a small population is separated from main population, preventing gene flow.

Sympatric speciation

A new species evolves while still inhabiting the same geographic region as the ancestral species.

Prezygotic barriers

Prevent mating or hinder fertilization.

Postzygotic barriers

Prevent a hybrid zygote from developing into a viable, fertile adult.

Habitat isolation

Species live in different areas or they occupy different habitats within the same area.

Temporal isolation

Species breed at different times of the day, year, or season.

Behavioral isolation

Unique behavioral patterns and rituals separate species.

Mechanical isolation

The reproductive anatomy of one species does not fit with the anatomy of another species.

Gametic isolation

Proteins on the surface of gametes do not allow for the egg and sperm to fuse.

Reduced hybrid viability

The genes of different parent species may interact in ways that impair the hybrid's development or survival.

Reduced hybrid fertility

A hybrid can develop into a healthy adult, but it is sterile.

Hybrid breakdown

The hybrid of the first generation may be fertile, but when they mate with a parent species or one another, their offspring will be sterile.

Microevolution

Change in allele frequencies within a single species or population.

Macroevolution

Large evolutionary patterns.

Punctuated equilibrium

When evolution occurs rapidly after a long period of stasis.

Gradualism

When evolution occurs slowly over hundreds, thousands, or millions of years.

Divergent evolution

Groups with the same common ancestor evolve and accumulate differences resulting in the formation of a new species.

Extinction

The termination of a species.

Homology

Characteristics in related species that have similarities even if the functions differ.

Comparative morphology

Analysis of the structures of living and extinct organisms

Fossil record

Gives a visual of evolutionary change over time