Unit 11 - Key Concepts in Evolutionary Biology

Adaptation

the dynamic evolutionary process that fits organisms to their environment, enhancing their evolutionary fitness

Adaptive Radiation

a rapid increase in the number of species with a common ancestor, characterized by great ecological and morphological diversity

Allopatric Speciation

a mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow.

Analogous Structure

features of different species that are similar in function but not necessarily in structure and which do not derive from a common ancestral feature

Bottleneck effect

the way in which a reduction and subsequent increase in a population's size affects the distribution of genetic variation among its individuals.

Convergent evolution

the process whereby distantly related organisms independently evolve similar traits to adapt to similar necessities

Divergent evolution

the evolutionary pattern in which species sharing a common ancestry become more distinct due to differential selection pressure which gradually leads to speciation over an evolutionary time period.

Founder effect

the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population.

Gene Flow

the movement of genes into or out of a population.

Gene Pool

the stock of different genes in an interbreeding population

Genetic Drift

variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce.

Homologous Structure

similar physical features in organisms that share a common ancestor.

Macroevolution

major evolutionary change. The term applies mainly to the evolution of whole taxonomic groups over long periods of time.

Microevolution

evolutionary change within a species or small group of organisms, especially over a short period.

Migration

any person who is moving or has moved across an international border or within a State away from his/her habitual place of residence

Modern Synthesis

the early 20th-century synthesis reconciling Charles Darwin's theory of evolution and Gregor Mendel's ideas on heredity in a joint mathematical framework.

Natural Selection

the process through which populations of living organisms adapt and change

Population Genetics

the study of the genetic composition of populations, including distributions and changes in genotype and phenotype frequency in response to the processes of natural selection, genetic drift, mutation and gene flow

Speciation

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

Sympatric speciation

occurs when there are no physical barriers preventing any members of a species from mating with another, and all members are in close proximity to one another

Variation

any difference between cells, individual organisms, or groups of organisms of any species caused either by genetic differences or by the effect of environmental factors on the expression of the genetic potentials

Vestigial structure

during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species.