BSC2010 Final

Charles Darwin and Alfred Wallace independently discovered

natural selection

Natural selection

differential survival and reproduction due to heritable traits

Darwin's postulates

heritable traits, overproduction of offspring, variation in traits

Adaptation

a heritable trait that increases survival and reproduction

Darwin's finch beak variation

beaks evolved to match different food sources

Evidence of evolution

fossils, homologous structures, vestigial structures, biogeography, molecular biology

Convergent evolution

unrelated species evolve similar traits due to similar environments

Homologous structures

traits shared due to common ancestry

Vestigial structures

reduced or nonfunctional structures

Biogeography

study of species distribution

Molecular evidence of evolution

DNA similarities show common ancestry

Artificial selection

humans selectively breed organisms for desired traits

Selective breeding

humans choose organisms with desired traits to reproduce

Species definition

group that can interbreed and produce fertile offspring

Gene pool

all alleles in a population

Hybrid

offspring of two different species

Population genetics

study of allele frequency change in populations

Allele frequency

proportion of an allele in a population

Hardy-Weinberg equilibrium

allele frequencies do not change over time

Hardy-Weinberg equation

p² + 2pq + q² = 1

Conditions of Hardy-Weinberg equilibrium

no mutation, no selection, no migration, random mating, large population

Evolutionary forces

mutation, gene flow, genetic drift, natural selection

Mutation

source of new genetic variation

Gene flow

movement of alleles between populations

Genetic drift

random change in allele frequencies

Natural selection

differential survival and reproduction of individuals

Founder effect

small group forms new population with different allele frequencies

Bottleneck effect

reduction in population size reduces genetic variation

Dispersal

movement of individuals to a new geographic area

Vicariance

physical barrier splits a population

Allopatric speciation

speciation due to geographic isolation

Sympatric speciation

speciation without geographic isolation

Adaptive radiation

rapid diversification into many species from one ancestor

Reproductive isolation

no gene flow between populations

Prezygotic barrier

prevents fertilization

Postzygotic barrier

prevents viable or fertile offspring

Temporal isolation

different breeding times prevent mating

Habitat isolation

different habitats prevent mating

Behavioral isolation

different mating behaviors prevent mating

Gametic barrier

sperm and egg cannot fuse

Hybrid inviability

offspring cannot survive development

Hybrid sterility

offspring cannot reproduce

Reinforcement

increased reproductive isolation due to low-fitness hybrids

Hybrid zone

area where two species interbreed

Punctuated equilibrium

rapid evolution followed by long periods of stability

Gradual speciation

slow continuous evolutionary change

Microevolution

change in allele frequencies within a population

Macroevolution

evolution above the species level

Assortative mating

mating with individuals similar to oneself

Inbreeding

mating between closely related individuals

Inbreeding depression

reduced fitness due to harmful recessive alleles

Cline

gradual change in traits across geography

Diversifying selection

favors extreme traits and increases variation

Stabilizing selection

favors average traits

Directional selection

favors one extreme trait

Sexual dimorphism

differences between males and females

Sexual selection

selection based on mating success

Good genes hypothesis

ornamental traits signal genetic quality and attract mates

Evolution has no purpose or direction

evolution is not goal-directed or purposeful

Individuals evolve

false; populations evolve

Mutation introduces new variation

true because mutation creates new alleles

Gene flow introduces new variation

true because alleles move between populations