AP BIO: Evolution Review

Evolution

(biology) the sequence of events involved in the evolutionary development of a species or taxonomic group of organisms

microevolution

evolution resulting from small specific genetic changes that can lead to a new subspecies

macroevolution

evolution on a large scale extending over geologic era and resulting in the formation of new taxonomic groups

phylogeny

(biology) the sequence of events involved in the evolutionary development of a species or taxonomic group of organisms

Lamark

before Darwin - use and disuse (parts that are used become bigger and stronger while other parts deteriorate) and inheritance of acquired characteristics (organism can pass on "modifications" to its offspring

use and disuse

body parts/structures that are needed or used become more developed over time, while those not used are less developed and will eventually disappear (Lamark)

acquired traits

Lamarck's felt these could explain why giraffes had long necks

natural selection

process by which individuals that are better suited to their environment survive and reproduce most successfully; also called survival of the fittest

darwinism

a theory of organic evolution claiming that new species arise and are perpetuated by natural selection

phylogeny

(biology) the sequence of events involved in the evolutionary development of a species or taxonomic group of organisms

homologous structures

Structures in different species that are similar because of common ancestry.

analogous structures

structures that do not have a common evolutionary origin but are similar in function

fitness

ability of an individual to survive and reproduce in its specific environment

adaptations

the behaviors and physical characteristics that allow organisms to live successfully in their environments

stabilizing selection

form of natural selection by which the center of the curve remains in its current position; occurs when individuals near the center of a distribution curve have higher fitness than individuals at either end

directional selection

form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve

disruptive selection

form of natural selection in which a single curve splits into two; occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle

sexual selection

A form of natural selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates.

artificial selection

selection by humans for breeding of useful traits from the natural variation among different organisms

sexual reproduction

reproduction involving the union or fusion of a male and a female gamete

genetic recombination

the regrouping of genes in an offspring that results in a genetic makeup that is different from that of the parents

diploidy

The state or condition of being diploid (having each chromosome in two copies per nucleus or cell)

outbreeding

mating outside of relatives

balanced polymorphism

Maintenance of two or more alleles in a population due to the selective advantage of the heterozygote

heterozygote advantage

Greater reproductive success of heterozygous individuals compared to homozygotes; tends to preserve variation in gene pools.

hybrid vigor

the characteristic of offspring that are stronger than their parents - produced through crossbreeding

frequency-dependent selection

A decline in the reproductive success of a morph resulting from the morph's phenotype becoming too common in a population; a cause of balanced polymorphism in populations.

neutral variation

genetic variation that does not appear to provide a selective advantage or disadvantage

gene flow

movement of alleles into or out of a population due to the migration of individuals to or from the population

genetic drift

The gradual changes in gene frequencies in a population due to random events

founder effect

when a few individuals become isolated from a larger population, this smaller group may establish a new population whose gene pool isn't reflective of the source population

bottleneck

A stressful period in which few organisms of a population survive, resulting in loss of genetic variation in the population.

nonrandom mating

mating between individuals of the same phenotype or by those who live nearby

Hardy-Weinberg equilibrium

theory of a stable, nonevolving population in which frequency of alleles do not change; only occurs in large, isolated populations with random mating, and no natural selection or mutations

p^2+2pq+q^2

hardy-weinberg equilibrium

species

(biology) taxonomic group whose members can interbreed

speciation

The process by which a new species evolves from a prior species, the most basic process in macroevolution.

allopatric speciation

The formation of a new species as a result of an ancestral population's becoming isolated by a geographic barrier.

sympatric speciation

The formation of a new species as a result of a genetic change that produces a reproductive barrier between the changed population (mutants) and the parent population. No geographic barrier is present.

polyploidy

A chromosomal alteration in which the organism possesses more than two complete chromosome sets.

hybridization

(genetics) the act of mixing different species or varieties of animals or plants and thus to produce hybrids

adaptive radiation

the development of many different forms from an originally homogeneous group of organisms as they fill different ecological niches (finches on islands)

prezygotic isolating mechanisms

Occurs before fertilization, prevents reproduction, prevents genotypes from entering gene pools

habitat isolation

prezygotic barrier between species; the species remain isolated because they breed in different habitats.

temporal isolation

form of reproductive isolation in which two populations reproduce at different times

behavioral isolation

form of reproductive isolation in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding

mechanical isolation

morphological differences can prevent successful mating

gametic isolation

Sperm of one species may not be able to fertilize the eggs of another species

postzygotic isolating mechanisms

mechanisms that allow fertilization but prevent hybrid offspring from surviving or reproducing

hybrid inviability

a type of postzygotic barrier between species; the species remain isolated because hybrid zygotes do not develop or hybrids do not become sexually mature

hybrid sterility

hybrid is functional adult, but not fertile. (ex: mule) (postzygotic)

hybrid breakdown

The first-generation hybrids are viable and fertile, but when they mate the offspring are feeble and sterile

divergent evolution

A form of evolution in which the same organism is placed into different environments with different selection pressures. This causes organisms to evolve differently, to diverge from their common ancestor. The resulting (new) species may share structural (but not necessarily functional) similarity; divergent evolution produces homologous structures.

convergent evolution

when two or more species NOT descended from a common ancestor develop similar traits

parallel evolution

Two related species that have made similar evolutionary adaptations after their divergence from a common ancestor

coevolution

The evolution of two or more species that is due to mutual influence, often in a way that makes the relationship more mutually beneficial

gradualism

The theory that evolution occurs slowly but steadily

punctuated equilibrium

a theory of evolution holding that evolutionary change in the fossil record came in fits and starts rather than in a steady process of slow change

chemical evolution

Formation of the earth and its early crust and atmosphere, evolution of the biological molecules necessary for life, and evolution of systems of chemical reactions needed to produce the first living cells. These processes are believed to have occurred about 1 billion years before biological evolution. Compare biological evolution.

heterotroph theory

the theory that posits that the first organisms were heterotrophs

endosymbiotic theory

theory that eukaryotic cells formed from a symbiosis among several different prokaryotic organisms