UF Bio 1 Exam 3

natural selection

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

genetic drift

A change in the allele frequency of a population as a result of chance events rather than natural selection.

Darwin's observations in the Galapagos

Organisms on the same continent were more similar that organisms living in the same temperature, organisms that existed on islands were different from related organisms on the mainland (some were endemic -- only existed-- to that island), and animals living on different islands had different traits.

fitness

Ability of an organism to survive and reproduce in its environment

adaptations

traits that improve an individual's ability to survive and reproduce

forces of evolution that generate variation

mutation and migration

forces of evolution that reduce variation

selection and non-random mating

mutation

heritable changes in genetic information that occur in individuals

fixation

when one allele is lost and the other becomes the only one present in the population

the bottleneck effect

A change in allele frequency following a dramatic reduction in the size of a population

the founder effect

change in allele frequencies as a result of the migration of a small subgroup of a population

gene flow

migration - movement of alleles from one population to another

random mating

individuals choose their mates without any preference for particular genotypes and phenotypes

sexual selection

when individuals select mates based on heritable traits

directional selection

occurs when natural selection favors one of the extreme variations of a trait

stabilizing selection

Natural selection that favors intermediate variants by acting against extreme phenotypes (decreases variation)

disruptive selection

favors individuals at both extremes of the phenotypic range; intermediate trait is selected against. can cause polymorphism

Polymorphism

more than one stable, discrete phenotype

heterozygote advantage

occurs when heterozygotes have a higher fitness than both homozygotes (sickle cell and malaria)

Geographic variation in natural selection

natural selection act in different ways on populations that live in different geographic regions

Frequency dependent selection

the fitness of a phenotype depends on how common it is in the population (left and right mouthed fish)

artificial selection

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

phenotypic variation =

genetic variation + environmental variation

Heritability

the fraction of variability that is due to genetic differences

positive selection

the rate of nonsynonymous substitutions exceed the rate of synonymous substitutions causing a directional shift that favors the spread of beneficial alleles

neutral selection

the rate of nonsynonymous substitutions equal the rate of synonymous substitutions causing random changes in the gene pool

negative/purifying selection

the rate of nonsynonymous substitutions is less than the rate of synonymous substitutions causing, causing stabilizing selection

Phylogeny

Evolutionary history of a species

lineage

Group claiming a common ancestor

taxon

group or level of organization into which organisms are classified

sister species

two species that are each other's closest relatives -- directly evolve from a common ancestor

clades

A group of species that includes an ancestral species and all its descendants.

homology

any heritable trait shared by more than one species and inherited from a common ancestor

synapomorphies

shared derived characters that provide evidence of common ancestry

convergent evolution

Process by which unrelated organisms independently evolve similarities (analogous characters) when adapting to similar environments

evolutionary reversal

the reversion of a derived character state to its ancestral state

Parisomony principle

the simplest explanation for observed data is the best explanation

monophyletic grouping

made up of an ancestral species and all of its descendants and no other species (same as monophyletic clade)

paraphyletic grouping

consists of an ancestral species and some, but not all, of the descendants ("repitles")

polyphyletic grouping

consists of various species that lack a common ancestor ("warm-blooded")

speciation

Formation of new species via reproductive isolation

species

a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding; unit for measuring biodiversity

morphological species concept

A definition of species in terms of measurable anatomical criteria. Problems: polymorphism (same species, different features) and cryptic species (look alike, but don't interbreed)

biological species concept

Species is a group of populations whose members have the potential to produce fertile offspring. Problems: doesn't apply to asexual organisms, cannot be applied to extinct species, and doesn't take into consideration species that can hybridize

lineage species concept

species as branches on a phylogeny

species complex

A grouping of very closely related species

Hardy-Weinberg equilibrium conditions

no mutations, random mating, no natural selection, extremely large population size, no gene flow

intersexual selection

Selection whereby individuals of one sex (usually females) are choosy in selecting their mates from individuals of the other sex; also called mate choice.

allopatric speciation

The formation of new species in populations that are geographically isolated from one another.

cryptic species

members of different species look alike but do not interbreed

Dobzhansky-Muller Model

split, mutate, fixation, incompatibility - A population is subdivided and then the two groups evolve independently. In each lineage, new alleles become fixed at different loci. The new alleles at the two loci are incompatible with one another. Genetic incompatibility between the two isolated populations will develop over time.

allopatric speciation

the process of speciation that occurs with geographic isolation

sympatric speciation

The formation of new species in populations that live in the same geographic area caused by disruptive selection, ecological speciation, polyploidy, temporal isolation, and behavioral isolation.

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