Evolution and the Changing Earth Study Guide

Comprehensive vocabulary flashcards covering key concepts of evolution, natural selection, speciation, and plate tectonics as outlined in the Unit Exam Study Guide.

Fitness

The ability of an organism to survive and reproduce in its environment, directly affecting natural selection.

Adaptation

An inherited characteristic that increases an organism's chance of survival and reproduction.

Phenotype

The physical characteristics or traits of an organism that natural selection acts upon directly.

Genetic Variation

The diversity in gene frequencies that already exists in a population, which evolution uses rather than creating what animals need.

Common Ancestor

The concept noted by Darwin that different species on the Galapagos had to have come from shared predecessors from the mainland.

Fossil Evidence

Information used to support evolution by showing how organisms have changed over time and where they were located geographically.

Vestigial Structures

Remnants of structures that served a function in an organism's ancestors but no longer have a clear or essential function in the modern organism.

Homologous Structures

Anatomical features in different species that are similar because they were inherited from a common ancestor.

Biogeography

The study of the distribution of species and ecosystems in geographic space and through geological time, used as evidence for evolution.

Artificial Selection

The process by which humans breed plants or animals for particular genetic traits.

Heterozygote Advantage

A situation where the heterozygous genotype has a higher fitness than either the homozygous dominant or homozygous recessive genotypes, such as in the sickle cell story.

Genetic Drift

A mechanism of evolution involving random changes in allele frequencies that affects smaller populations more significantly than larger ones.

Bottleneck Effect

A type of genetic drift that occurs when a population's size is reduced for at least one generation, significantly reducing genetic variation.

Founder Effect

A type of genetic drift that occurs when a new population is established by a very small number of individuals from a larger population.

Speciation

The formation of new and distinct species in the course of evolution.

Geographic Isolation

A form of reproductive isolation where two populations are separated by physical barriers such as rivers, mountains, or bodies of water.

Behavioral Isolation

A form of reproductive isolation based on differences in courtship rituals or other behaviors that prevent interbreeding.

Temporal Isolation

A form of reproductive isolation where two or more species reproduce at different times of the day, season, or year.

Allopatric Speciation

Speciation that occurs when biological populations of the same species become vicariant, or isolated from each other to an extent that prevents genetic exchange.

Sympatric Speciation

The process through which new species evolve from a single ancestral species while inhabiting the same geographic region.

Stabilizing Selection

A type of natural selection in which the population mean stabilizes on a particular non-extreme trait value.

Directional Selection

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.

Disruptive Selection

Natural selection in which extreme values for a trait are favored over intermediate values, potentially leading to speciation.

Cladogram

A branching diagram (phylogenetic tree) showing the relationship between a number of species, where branch-points represent common ancestors.

Gradualism

The model of evolution that suggests changes occur slowly and steadily over long periods of time.

Punctuated Equilibrium

The model of evolution characterized by long periods of stability (stasis) interrupted by brief periods of rapid change.

Convergent Evolution

The process whereby organisms not closely related independently evolve similar traits as a result of having to adapt to similar environments.

Divergent Evolution

The process by which a species evolves into two or more descendant or different forms.

Hardy-Weinberg Equation (Alleles)

$$p + q = 1$$

Hardy-Weinberg Equation (Genotypes)

$$p^2 + 2pq + q^2 = 1$$

Genetic Equilibrium

A condition in which a population's allele frequencies remain constant over generations, meaning evolution is NOT occurring.

Plate Tectonics

The theory that the Earth's outer shell is divided into several plates that glide over the mantle, explaining the distribution of fossils and continental drift.