Evolution of Populations – Key Vocabulary

A comprehensive set of vocabulary flashcards covering mechanisms, evidence, and terminology of evolutionary biology from the provided lecture notes.

Natural Selection

The evolutionary process where individuals with advantageous inherited traits survive and reproduce more successfully than others.

Fitness (evolutionary)

A relative measure of an organism’s ability to survive and produce fertile offspring in its environment.

Adaptation

An inherited characteristic that enhances an organism’s survival or reproduction in a specific environment.

Unity of Life

Darwin’s concept that all organisms share common characteristics because of descent from a common ancestor.

Diversity of Life

Darwin’s concept that species differ from one another due to adaptations accumulated over time.

Artificial Selection

Human-directed breeding that selects for desired traits in other species.

Variation (Observation #1)

The fact that members of a population differ in their inherited traits.

Overproduction of Offspring (Observation #2)

All species can produce more offspring than the environment can support.

Inference #1

Individuals with traits that enhance survival/reproduction leave more offspring.

Inference #2

Favorable traits accumulate in a population over generations.

Lamarckism

The unsupported hypothesis that evolution occurs through use and disuse of body parts and the inheritance of acquired characteristics.

Adaptive Evolution

Evolutionary change that results in a better match between organisms and their environment, primarily via natural selection.

Heritable Variation

Genetic differences among individuals that can be passed to offspring and serve as raw material for evolution.

Population (evolutionary unit)

A group of interbreeding individuals of one species that share a common gene pool.

Speciation

The process by which one species splits into two or more separate species.

Directional Selection

Natural selection that favors individuals at one phenotypic extreme.

Disruptive Selection

Selection that favors individuals at both phenotypic extremes over intermediates.

Stabilizing Selection

Selection that favors intermediate variants and acts against extremes.

Sexual Selection

Selection in which individuals with certain traits are more likely to obtain mates.

Intrasexual Selection

Direct competition among individuals of one sex (usually males) for mates.

Intersexual Selection

Mate choice; individuals of one sex (usually females) choose mates based on certain traits.

Microevolution

A change in allele frequencies within a population over generations.

Macroevolution

Evolutionary change above the species level (e.g., origin of new taxonomic groups).

Mutation

A change in DNA sequence; the ultimate source of new genetic variation.

Genetic Drift

Random fluctuations in allele frequencies that reduce genetic variation, especially in small populations.

Founder Effect

Genetic drift that occurs when a few individuals start a new population with a gene pool different from the source population.

Bottleneck Effect

A severe drop in population size that randomly alters allele frequencies and reduces genetic diversity.

Inbreeding

Mating between closely related individuals, increasing homozygosity without changing allele frequencies.

Gene Flow

The movement of alleles among populations via migration of individuals or gametes.

Gene Pool

All copies of every allele at every locus in all members of a population.

Allele Frequency

The proportion of a specific allele among all allele copies in a population (p + q = 1).

Homology

Similarity in characteristics resulting from shared ancestry.

Analogous Structures

Features with similar function but independent evolutionary origin; result of convergent evolution.

Convergent Evolution

Independent evolution of similar traits in distantly related lineages due to similar environmental pressures.

Vestigial Structures

Remnants of features that served a function in an organism’s ancestors.

Fossil Record

The ordered array of fossils, providing evidence of extinction, origin of groups, and evolutionary change.

Biogeography

The scientific study of the geographic distribution of species.

Endemic Species

Species found nowhere else in the world, often on islands or isolated regions.

Phylogeny

The evolutionary history of a species or group of related species.

Systematics

The discipline focused on classifying organisms and determining their evolutionary relationships.

Binomial Nomenclature

Linnaeus’s two-part scientific naming system for species (genus + specific epithet).

Taxon

A taxonomic group of any rank, such as species, genus, or family.

Type Specimen

The original specimen designated to define and anchor the name of a species.

Clade

A monophyletic group consisting of an ancestor and all of its descendants.

Monophyletic Group

A group that includes a common ancestor and all its descendants (synonymous with clade).

Paraphyletic Group

A group that includes a common ancestor but not all of its descendants.

Polyphyletic Group

A group lacking the most recent common ancestor of all members; formed from distantly related taxa.

Maximum Parsimony

A method that selects the phylogenetic tree requiring the fewest evolutionary changes.

Horizontal Gene Transfer

The movement of genes between different species’ genomes, not by descent.

Orthologs

Homologous genes separated by a speciation event.

Paralogs

Homologous genes produced by gene duplication within a genome.

Xenologs

Homologous genes resulting from horizontal gene transfer events.