Evolution and Natural Selection

Flashcards covering key vocabulary terms related to evolution and natural selection.

Evolution

The process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the Earth, primarily driven by natural selection.

Natural Selection

The process by which organisms better adapted to their environment tend to survive and produce more offspring, leading to the gradual increase of advantageous traits in a population over generations.

Population

A group of individuals of the same species living in the same geographical area that can interbreed.

Adaptation

A feature or trait that allows an organism to survive and reproduce more effectively in its environment, often developed through natural selection.

Variation

Differences in physical traits, behaviors, or genetic makeup among individuals within a population.

Evolutionary Fitness

A measure of an organism's ability to survive and reproduce in its environment, contributing its genes to the next generation; it is relative to other individuals in the population.

Fossil Record

The total number of fossils that have been discovered, as well as the information derived from them, providing evidence of the history of life on Earth.

Biochemical Evidence

Evidence for evolution based on similarities in the genetic code (DNA/RNA), proteins, and metabolic processes among different species, suggesting common ancestry.

Comparative Anatomy

The study of similarities and differences in the anatomy of different species, used to infer evolutionary relationships.

Homologous Structures

Structures in different species that are similar because of common ancestry, even if they have different functions (e.g., the forelimbs of humans, cats, whales, and bats).

Analogous Structures

Structures in different species that have similar functions but evolved independently and do not share a common ancestry (e.g., the wings of a bird and the wings of an insect).

Vestigial Structures

A structure in an organism that has lost all or most of its original function in a species through evolution (e.g., the human appendix or whale pelvis).

Phylogenetic Tree

A branching diagram or 'tree' showing the inferred evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical or genetic characteristics.

Common Ancestor

An ancestral species from which two or more species or groups of organisms descended.

Sequence Divergence

The accumulation of differences in the nucleic acid (DNA or RNA) or protein sequences between two species or populations, indicating the time elapsed since their last common ancestor.

Antibiotic Resistance

The ability of bacteria or other microorganisms to withstand the effects of an antibiotic to which they were once sensitive, a result of natural selection favoring resistant strains.

Convergent Evolution

The independent evolution of similar features in species of different lineages, typically as a result of adapting to similar environments or ecological niches (e.g., the streamlined body shape of dolphins and sharks).

Divergent Evolution

The accumulation of differences between groups which can lead to the formation of new species, often due to different environmental pressures or geographic isolation (e.g., the adaptive radiation of finches on the Galapagos Islands).

Sexual Selection

A mode of natural selection where members of one biological sex choose mates of the other sex to mate with (intersexual selection), and compete with members of the same sex for access to mates (intrasexual selection).

Stabilizing Selection

A type of natural selection in which genetic diversity decreases as the population mean stabilizes on a particular non-extreme trait value, favoring intermediate phenotypes and acting against extreme variations.

Disruptive Selection

A type of natural selection that favors individuals at both extremes of the phenotypic range over intermediate phenotypes, potentially leading to speciation as two distinct groups emerge.

Directional Selection

A type of natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype.