Unit 2 Exam Flashcards
Hitchhiking
when a non beneficial allele increases in frequency because it’s linked to a beneficial trait
Selective Sweep
fixation of a beneficial allele
Balancing Selection
genetic diversity by keeping both alleles present
Overdominants
heterozygotes with higher fitness than either homozygotes
Negative Frequency Dependent Selection
favors rare allele
Multiple Niche Polymorphism
different genotypes maintained in different environments
Selection favoring dominant alleles
results in a loss of genetic variation
Underdominance
heterozygotes have a disadvantage
Positive Frequency Dependent Selection
favors the more common allele
Adaptive landscape
how populations evolve, selection will move uphill
Neutral Theory
Not under selection constraints
dn/ds ratio
measures the difference between nonsynonymous mutation and synonymous mutations
local adaptation
sites in the genome with high divergence in isolated populations
Quantitative Trait Loci
region of the genome that affects a quantitative trait and can be used to examine genetically variable loci in disparate populations
Disruptive Selection
selection of a quantitative trait which shifts the mean towards both extremes and away from the mean
Heritability
a measure of likeness between parental and offspring for a specific trait
Stabilizing Selection
selection of a quantitative trait which shifts the population towards the mean
Directional Selection
selection of a quantitative trait which shifts the mean towards one extreme
Coalescence
the period in the past in which two lineages converge on a shared common ancestor
Inbreeding Load
fixation of deleterious alleles in a small population, resulting in overall decreased fitness
Founder Event
when a small population becomes isolated from the original population, drastically reducing the gene pool
Bottleneck
short term reduction in population size which likely results in a drastic mis-sampling of the gene pool
Effective Population Size
the realized number of individuals in a population which are contributing genetic material to the subsequent generation
Cline
Smooth change in allele frequency or the mean of a character across a geographic transect
QTL
Changes in the genome can be detected in different populations and mapped to adaptive environmental traits
Mechanical Isolation
Prezygotic, Reproductive structures are incompatible
Sexual Isolation/Assortive Mating
Prezygotic, do not recognize other individuals due to a m ismatch in body size
Ecological Inviability
Postzygotic, Hybrid offspring have lower rates of survivorship than parents
Temporal
Prezygotic, mating occurs at different times of the year (cicadas)
β>0
positive selection
β<0
negative selection
β=0
no directional selection
Fsub st= 0
genetically the same
Fsub st= 1
genetically distinct
var (p)
variation in allele frequency
(1-p̄)
is pretty much q, mean allele frequency of Allele 2
Plasticity
ability of an organism to develop phenotypic difference to adapt to environment
gene flow
movement of alleles to one population or another, equalizes allele frequency; will introduce new alleles
migration rate
proportion of individuals in a population that arrives from another each generation
o^2
variance
Allele swamping
s«m migration of overwhelm any local adaptation lead to loss of allele
Bergmann’s Rule
cline in mammals/birds where population in cooler climates have higher body mass
Underdominance
heterozygotes have disadvantage over both homozygotes
tension zone
area that is an abrupt distinction in phenotype; maintained by underdominance
Dispersal
Movement
