Unit 7: Evolution

Natural Selection

The process by which organisms better adapted to their environment tend to survive and produce more offspring.

Adaptation

A trait that helps an organism survive and reproduce in its environment.

Gene Flow

The transfer of genetic material between populations, increasing genetic diversity.

Genetic Drift

Random changes in allele frequencies in a population, often having a significant effect in small populations.

Speciation

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

Allopatric Speciation

Speciation that occurs when biological populations are physically separated.

Sympatric Speciation

Speciation that occurs without physical separation, often through reproductive isolation.

Phylogenetics

The study of evolutionary relationships among biological entities.

Common Ancestor

A species from which two or more different species have evolved.

Fossil Record

The history of life as documented by fossils, providing evidence for evolution.

Homologous Structures

Anatomical features in different species that are similar due to shared ancestry.

Analogous Structures

Anatomical features in different species that serve similar functions but evolved independently.

Vestigial Structures

Body parts that have lost their original function through evolution.

Biogeography

The study of the geographical distribution of living organisms and fossils.

Population Genetics

The branch of genetics that studies genetic variability within populations.

Microevolution

Small scale evolutionary changes within a species.

Macroevolution

Large scale evolutionary changes that occur over long periods.

Fitness

The ability of an organism to survive and reproduce in its environment.

Punctuated Equilibrium

The theory that species evolve during short periods of rapid change followed by long periods of stability.

Gradualism

The theory that evolution occurs slowly but steadily over time.

Taxonomy

The science of classifying living organisms.

Endemic Species

Species that are native to and found only within a specific geographic area.

Extinction

A permanent loss of a species from the earth.

Adaptive Radiation

The diversification of a group of organisms into forms filling different ecological niches.

Co-evolution

The influence of closely associated species on each other in their evolution.

Sexual Selection

A form of natural selection where certain traits increase mating success.

Mimicry

An adaptation where one species evolves to resemble another.

Camouflage

An adaptation that allows an organism to blend in with its environment.

Theory of Evolution

The scientific theory that species change over time through mechanisms like natural selection.

Origin of Species

Charles Darwin's book detailing his theory of evolution and natural selection.

Population Bottleneck

A sharp reduction in the size of a population due to environmental events.

Founder Effect

Reduced genetic diversity that results when a population is descended from a small number of ancestors.

Cladistics

A method of classifying species based on common ancestry.

Convergent Evolution

The process where unrelated organisms evolve similar traits due to similar environmental pressures.

Divergent Evolution

The process where two or more related species become more dissimilar over time.

Biological Species Concept

Defines a species as a group of organisms that can interbreed and produce fertile offspring.

Reproductive Isolation

Barriers that prevent different species from interbreeding.

Prezygotic Isolation

Barriers that occur before fertilization.

Postzygotic Isolation

Barriers that occur after fertilization.

Trait Homology

The similarity of characteristics resulting from shared ancestry.

Gene Pool

The total collection of genes in a population at any one time.

Allele Frequency

How often an allele appears in a gene pool.

Heredity

The passing of traits from parents to offspring.

Morphological Traits

Physical characteristics of an organism used to identify and classify species.

Molecular Evidence

Genetic data supporting evolutionary relationships.

Evolutionary Developmental Biology

The study of the relationship between development and evolution.

Horizontal Gene Transfer

The movement of genetic material between organisms other than via vertical transmission.

Transitional Fossils

Fossils that show intermediary states between an ancestral form and that of its descendants.

Homoplasy

Similar traits that arise independently in different species.

Genetic Variability

The tendency of genetic characteristics to vary within a population.

Phenotypic Plasticity

The ability of an organism to change its phenotype in response to environmental changes.

Interspecific Competition

Competition between different species for resources.

Intraspecific Competition

Competition among members of the same species.

Ecological Niche

The role and position a species has in its environment.

Niche Partitioning

The process by which competing species use the environment differently to coexist.

Fitness Trade-Offs

Compromises between traits that affect fitness in different ways.

Gene Sequencing

Determining the nucleotide order of a given gene.

Evolutionary Fitness

The contribution of a genotype to the next generation's gene pool.

Artificial Selection

The process of humans selectively breeding plants and animals for desired traits.

Phenotype

The observable physical or biochemical characteristics of an organism.

Genotype

The genetic constitution of an organism.

Stabilizing Selection

Natural selection that favors average phenotypes.

Directional Selection

Natural selection that favors one extreme phenotype over the mean.

Disruptive Selection

Natural selection that favors extreme phenotypes at both ends.

Biochemical Evidence

Molecular evidence supporting the theory of evolution.

Genetic Engineering

The direct manipulation of an organism's genes using biotechnology.

Nucleotide

The basic building block of DNA and RNA.

Chromosomal Mutation

A change in the structure or number of chromosomes.

Transposable Elements

DNA sequences that can change position within the genome, also known as 'jumping genes'.

Phylogeography

The study of the historical processes that may be responsible for the contemporary geographic distributions of individuals.

Natural Variation

Differences among individuals in a population.

Scientific Theory

A well-substantiated explanation for a phenomenon based on a body of evidence.

Embryonic Development

The development of an embryo from fertilization to birth or hatching.

Ecosystem Stability

The resilience of an ecosystem to disturbances.

Evolutionary Psychology

The study of the evolutionary basis of human behavior.

Molecular Clock

A technique that uses mutation rates to estimate the time of divergence between species.

Species Richness

The number of different species represented in a given ecological community.