Chapter 27 - Principals of Biology

evolution

Genetic change in a species over time, resulting in the development of genetic and phenotypic differences that are the basis of natural selection; descent of organisms from a common ancestor.

natural selection

Mechanism of evolutionary change caused by environmental selection of organisms most fit to reproduce; results in adaptation to the environment.

inheritance of acquired characterisitics

Lamarckian belief that characteristics acquired during the lifetime of an organism can be passed on to offspring.

epigenetic inheritance

An inheritance pattern in which a nuclear gene has been modified but the changed expression of the gene is not permanent over many generations; the transmission of genetic information by means that are not based on the coding sequences of a gene.

adaptation

Species' modification in structure, function, or behavior that makes a species more suitable to its environment.

fossil

Any past evidence of an organism that has been preserved in the Earth's crust.

transitional links

Evidence of evolution, typically fossils, that bear a resemblance to two groups that in the present day are classified separately.

biogeography

Study of the geographic distribution of organisms.

continental drift

The movement of the Earth's crust by plate tectonics, resulting in the movement of continents with respect to one another.

homologous structure

A structure that is similar in different types of organisms because these organisms descended from a common ancestor.

analogous structure

Structure that has a similar function in separate lineages but differs in anatomy and ancestry.

vestigial structure

Remnant of a structure that was functional in some ancestor but is no longer functional in the organism in question.

artifical selection

Intentional breeding of certain traits, or combinations of traits, over others to produce a desirable outcome.

microevolution

Change in gene frequencies between populations of a species over time.

population genetics

The study of gene frequencies and their changes within a population.

population

Group of organisms of the same species occupying a certain area and sharing a common gene pool

gene pool

Total of the alleles of all the individuals in a population.

genetic equilibrium

Description for a population in which the frequency of alleles for a given trait is not changing over time.

hardy-weinberg equilibrium

Mathematical law stating that the gene frequencies in a population remain stable if evolution does not occur due tononrandom mating, selection, migration, and genetic drift.

mutation

Change in the nucleotide structure of an organism's DNA.

genetic drift

Mechanism of evolution due to random changes in the allelic frequencies of a population; more likely to occur in small populations or when only a few individuals of a large population reproduce.

bottleneck effect

Type of genetic drift; occurs when a majority of genotypes are prevented from participating in the production of the next generation as a result of a natural disaster or human interference.

founder effect

Cause of genetic drift due to colonization by a limited number of individuals who, by chance, have different genotype and allele frequencies than the parent population.

gene flow

Sharing of genes between two populations through interbreeding.

nonrandom mating

Mating among individuals on the basis of their phenotypic similarities or differences, rather than mating on a random basis.

fitness

Ability of an organism to reproduce and pass its genes to the next fertile generation; measured against the ability of other organisms to reproduce in the same environment.

stabilizing selection

Outcome of natural selection in which extreme phenotypes are eliminated and the average phenotype is conserved.

directional selection

Outcome of natural selection in which an extreme phenotype is favored, usually in a changing environment.

disruptive selection

Outcome of natural selection in which the two extreme phenotypes are favored over the average phenotype, leading to more than one distinct form.

macroevolution

Large-scale evolutionary change, such as the formation of new species.

species

Group of similarly constructed organisms capable of interbreeding and producing fertile offspring; organisms that share a common gene pool; the taxon at the lowest level of classification.

prezygotic isolating mechanism

Anatomical, physiological, or behavioral difference between two species that prevents the possibility of mating.

postzygotic isolating mechanisms

Processes that result in the production of sterile offspring between two different species.

speciation

Origin of new species due to the evolutionary process of descent with modification.

Allopatric speciation

Model that proposes that new species arise due to an interruption of gene flow between populations that are separated geographically.

sympatric speciation

Origin of new species in populations that overlap geographically

adaptive radiation

Rapid evolution of several species from a common ancestor into new ecological or geographic zones.

gradualistic model

Model of genetic change in a species which suggests that change occurs at a slow, steady pace over time.

punctuated equilibrium

Model of evolutionary change in a species which suggests that there are long periods of little or no change, followed by brief periods of rapid speciation.

systematic biology

Another name for the study of systematics, or the study of the evolutionary relationships between species.

systematics

Study of the diversity of life for the purpose of understanding the evolutionary relationships between species.

taxonomy

Branch of biology concerned with identifying, describing, and naming organisms.

phylogenetics

Area of systematic biology that uses evidence to construct phylogeny, or a hypothesis of the evolutionary relationships between species.

phylogeny

Area of systematic biology that uses evidence to construct phylogeny, or a hypothesis of the evolutionary relationships between species.

cladistics

Method of systematics that uses derived characters to determine monophyletic groups and construct cladograms.

convergent evolution

Similarity in structure in distantly related groups, generally due to similar selective pressures in like environments.

supergroup

Systematic term used to classify the major groups of eukaryotes based on DNA similarities