third quiz Flashcards
what are the two types of evolutionary genetics ?
population genetics
quantitative genetics
what is population genetics
study of the fate of alleles at one or more loci
p and q stuff
what is quantitave genetics
study of traits assumed to be controlled by many loci
is height in humans population genetics or quantitative genetics
quantitative
what are the different ways alleles at a loci affect phenitypes
dominance
epistasis
pleiotropy
plasticity
what is dominance
interactions between alleles at a loci
normal recessive/dominance stuff
what is epistasis
interactions across loci
effect of a gene mutation is dependant on the presence of absence of a mutation on one or more genes
what is pleiotropy
interactions across traits
when one gene influences multiple seemingly unrelated phenotypic traits
what is plasticity
interactions with environment
change in the expressed phenotype of a genotype as a result of the environment
what is codominance
both alleles in the genotype are seen in the the phenotype
what is incomplete dominance
when the phenotypes of the parents blend together to create a new phenotype
what does the hardy Weinberg equation describe
the unchanging frequency of alleles in a stable, idealized population
what does hardy Weinberg assume
large populations, no selection, no migration, random mating, no mutation
in hardy Weinberg equilibrium do allele frequencies change over time
no
what are the classes of selection
viability selection
fecundity selection
what is viability selection
differences in survival probabilities
what is fecundity selection
differences in reproductive success
how do new dominant mutations affect frequency and fixation
increase in frequency rapidly
approaches fixation slowly
how do new recessive mutations affect frequency and fixation
increase frequency very slowly
once they are common they reach fixation very quickly
Are most new mutations recessive or dominant
most are at least partially recessive
what are ways genetic variation is maintained
- recessive alleles linger even if selected against
- directly via selection (ex:heterozygote advantage, frequency-dependant selection, mosaic evolution that counteracts migration)
- via recurrent mutation
- via drift
what is a heterozygote advantage
when the heterozygote has a higher fitness than the homozygote
what is frequency dependant selection
each selection coefficient is a function the frequencies of the different genotypes.
pretty much frequency of the genotypes influences likelihood of getting that genotype
what is mosaic evolution
different geographic locations lead to different fitnesses for the same allele
what is mutation selection balance
new copies of alleles keep arising by mutation making it so it persists at a low frequency
what are Darwins 2 big ideas
natural selection
decent with modification
what is homology
similarities due to a common ancestor
what is analogy
similarities due to convergent evolution
what is apomorphy
when a species/clade shows a trait that identifies it from the ancestral form
symplesiomorphy
a characteristic shared by 2 or more taxa and their most recent common ancestor
what is plesiomorphy
ancestral trait
what is autapomorphy
a distinctive feature (derived trait) that is unique to a taxon (only found in one taxon)
what is a synapomorphy
characteristic shared by a group of taxa due to common ancestor
what is homoplasy
a characteristic shared by a set of species but not their common ancestor
what are the three parts of a phylogenetic tree
tips, nodes, branches
what is each branch and node represent
a phylogenetic species
what is a root
a common ancestor of all taxa in the tree
what is a sister group
closest living species relative to another
what do rooted trees incorporate
relative time
what is an outgroup
taxon outside of group of interest (ingroup)
what do cladograms represent
relative relationships
what do additive trees show
branch lengths represent the amount of change and isn’t indicative of the amount of time
what do ultrametric trees show
branch lengths show relative time
all living species are same distance from the root
order types of trees from least complex (amount of information shown) to most
unrooted trees
cladogram
additive tree
ultranetric tree
what is polytomy
a node on a phylogeny with more than 2 decendant lineages emerging
what does it mean to be bifurcating (dichotomous)
to divide into 2 branches
what is a monophyletic group (clade)
consists of a node and all of its descendants
what is a paraphyletic group
contains a node and some but not all descendants
what is a polyphyletic group
when two lineages convergently evolve similar character states
