bio evolution.

evolution

change in genetic composition of biological population over time

parsimonious

simplest explanation w unnecessary assumptions

atrophy

loss/reduction of unimportant traits

artificial selection

selective breeding

sexual dimorphism

differences btw males and females in same species

genetic drift

random changes in allele frequencies

population bottlenecks

large portion of population reduced

3 requirements for natural selection to occur

variation, heritability, reproductive success

deleterious

harmful

gene pool

sum of all alleles for one locus

adaptation

beneficial mutation

heritability

fraction of a variation of a trait that is genetic

fitness

likeliness of a trait to be passed on

gene flow

exchange of genetic material from one population to another

genetic drift

random fluctuations in allele frequencies

founder effect

few individuals isolated from population, higher risk of genetic drift

fixation

only one allele present in the population

directional selection

when an extreme phenotype is fittest

stabilizing/purifying selection

intermediate trait is the fittest

disruptive selection

traits on both extremes are fittest

balancing selection

the frequency of more than one phenotype is maintained

polymorphism

multiple alleles

frequency-dependent selection

when fitness depends on frequency

intersexual selection

selection of traits that make one sex more attractive to the other

intrasexual selection

traits that assist in competition between same sex to access mates

assortive mating

more likely to mate if genotypes/phenotypes similar

dis-assortive mating

more likely to mate with different genotypes/phenotypes

monomorphic

only 1 allele at a locus

genetic structure

frequency of diff alleles and genotypes

allele frequency

p+q=1

genotype frequency

p² + 2pq + q² = 1

hardy-weinberg equilibrium

allele and genotype frequency do not change unless acted upon

conditions for hardy-weinberg equilibrium

no mutation, no selection, random mating, no gene flow, no genetic drift/large population size

pseudogenes

copies of genes that are no longer functioning

neutral theory

majority of variants are selectively neutral at a molecular level

neutral variants become fixed through__

genetic drift

probability of any allele becoming fixed =

frequency in gene pool

1/2N

prob a new mutation will be fixed by drift alone

2Nmu

#of new mutations in a population

two fold cost of sex

-cost of meiosis

-cost of males

cost of meiosis

females only pass on 50% of genes

cost of males

genders reduce reproductive rate

advantages of asexual reproduction

-quickly spread

-more asexual mutants

advantages of sexual reproduction

-elimination of deletrious mutations

-variation

-repair damaged dna

genetic load/ratchet

deleterious mutations accumulate

novel

new

gene duplication results in (4 options)

both copies retain function

each copy specializes

one copy loses function

one copy evolves

phylogeny

evolutionary history of a group

binomial nomenclature

genus + species name

taxonomy

hierarchical way of categorizing species

sister taxa

two closest relatives to each other

sister clades

two clades’ closest relatives

clade

most recent common ancestor and only its descendants (snip)

monophyletic

one ancestor and all descendants

paraphyletic

does not include all descendants of common ancestor

polyphyletic

doesn’t include common ancestor

outgroup

reference group, closely related but not in same group

convergent evolution

when similar traits evolved independently in different lineages

homoplasies/homoplastic traits

shared between taxa but not homologous

synapomorphies

shared and derived traits

characters used to build phylogenies (4)

morphological, developmental, behavioral, molecular

morphological traits

observable physical traits

strengths of using morphological traits

extinct species

fossil evidence

weaknesses of using morphological traits

hard to compare distantly related orgs

some traits from environment

strengths of using developmental traits

when form changes in adults

learn about diversification

weaknesses of using developmental traits

some traits have multiple functions in different lineages

strengths of using behavioral traits

heritable

weaknesses of using behavioral traits

plastic

measurement difficult

plastic (adj)

a trait that changes with the environment

strengths of using molecular traits

a lot of dna to use

know a lot about trait exchange in dna

rates of change vary among loci

weaknesses of using molecular traits

only 4 trait states per character

homoplasies common

homologous

derived from common ancestor

species

orgs that mate with each other

morphological species concept

practical identification

limitations of morphological species concept

regional variation

sexual dimorphism

cryptic species

cryptic species

visually same but don’t reproduce

biological concept

reproductive isolation

limitations of biological concept

ring species

asexual species

hybridization

extinct species

hybridization

2 diff species produce infertile offspring

lineage concept

genetic divergence

lineage concept limitations

some can interbreed but have genetic divergence

some not reproductively isolated

ecological concept

separate ecotypes isoloation

analogous structures

similar functions but do not share a common ancestor

vestigial structure

trait inherited from an ancestor but has lost its function

allopathic speciation

a geographic barrier separates populations

sympatric speciation

speciation occurs in the same area

gametic isolation

gametes won’t fuse

phanerozoic era

time after precambian era