Evolution Vocab Terms

Adaptation

A form of HERITABLE trait that enhances an individual's fitness

Adaptive radiation

Macroevolutionary pattern in which a lineage undergoes a BURST of genetic divergences that gives rise to many species

Allele frequency

PROPORTION of one allele relative to all alleles at a particular locus in a population's chromosomes

Allopatric speciation

SPECIATION pattern in which a physical barrier arises and SEPARATES populations, ending gene flow between them

Analogous structure

SIMILAR body structures that evolved separately in different lineages (by morphological convergance)

Balance Polymorphism

MAINTAINANCE of two or more alleles of a gene at high frequency in a population

Biogeography

STUDY of patterns in the geographic distribution of species and communities

Bottleneck

REDUCTION in population size so severe that it REDUCES genetic diversity

Coevolution

The JOINT evolution of two closely interacting species; macroevolutionary pattern in which each species is a selective agent for traits of the other

Comparative morphology

Scientific study of SIMILARITIES and DIFFERENCES in body plans

Directional selection

MODE OF NATURAL SELECTION in which forms of a trait at one end of a range of variation are adaptive

Disruptive selection

Mode of natural selection in which forms of a trait at both ends of a large variation are adaptive, INTERMEDIATE FORMS ARE SELECTED AGAINST

Evolution

CHANGE in a line of descent

Fitness

Degree of ADAPTATION to an environment, as MEASURED by the individuals relative genetic contribution to future generations

Fixed allele

Refers to an ALLELE for which ALL members of a population are homozygous

Fossil

Physical evidence of an organism that lived in the ancient past

Founder effect

After a small group of individuals FOUND a new population, allele frequencies in the new population differ from those in the original population

Frequency Dependent Selection

Natural selection in which a trait's adaptive value DEPENDS on its FREQUENCY among members of a population

Gene flow

The MOVEMENT of alleles between populations

Gene pool

All the alleles of all the genes in a population; a POOL of genetic resources

Genetic drift

Change in allele frequency DUE to chance alone

Genetic equilibrium

THEORETICAL STATE in which an allele's frequency never changes in a population's gene pool.

Half Life

Refers to the time it takes for a quantity of a substance to decay to half of its original amount.

Homologous structure

Body STRUCTURES that are SIMILAR in different lineages because they evolved in a common ancestor

Macroevolution

Evolutionary patterns and trends on a LARGER SCALE THAN MICROEVOLUTION; e.g., adaptive radiation, coevolution

Microevolution

Change in ALLELE FREQUENCY

Morphological convergence

Evolutionary pattern in which similar body parts (analogous structures) evolve SEPARATELY in different lineages

Morphological divergence

Evolutionary pattern in which a body part of an ancestor changes DIFFERENTLY in its DIFFERENT DESCENDANTS

Natural selection

A major mechanism of evolution: the differential survival and reproduction of individuals of a population based on differences in shared heritable traits. Outcome in ENVIRONMENTAL pressures

Parapatric speciation

SPECIATION PATTERN in which populations SPECIATE while in contact along a common border

Plate tectonics theory

THEORY that Earth's outmost layer of rock is cracked into plates, the slow movement of which conveys continents to new locations over geologic time

Population

A group of organisms of the same species who live in a specific location and breed with one another more often than they breed with members of other populations

Radiometric dating

Method of estimating the AGE of a rock or fossil by measuring the content and proportions of a RADIOISOTOPE and its daughter elements

Reproductive isolation

The END of gene flow between POPULATIONS; part of speciation

Sexual dimorphism

A trait that DIFFERS between MALES and FEMALES of a species

Sexual selection

Mode of natural SELECTION in which some individuals out REPRODUCE others of a population because they are better at securing mates

Speciation

EMERGENCE of a new SPECIES

Stabilizing selection

Mode of natural selection in which an intermediate form of a trait is ADAPTIVE, and extreme forms are selected against

Sympatric speciation

SPECIATION pattern in which SPECIATION occurs within a population, in the absence of a physical barrier to gene flow.

Vestigal structure:

Remnants of STRUCTURE that were once functional in an ancestor; usually reduced in size and serve zero/no function

allopatric

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