Evolution

transposition

the production of copies that become inserted into new positions in the genome

Kinds of mutations

Gene mutations (bp substitutions, point mutations, transition, transversion, frameshift mutations)RecombinationTransposable elements --> cause changes

synonymous mutations vs. nonsynonymous

synonymous: no efect on amino acid sequence of the protein (often in coding region)Nonsynonymous: result in amino acid substitutions

Intragenic Recombination

when homologous DNA sequences differ at two or more ase pairs -- generates new gene combinations

recurrent mutation

repeated origin of a particular mutation

back mutation

mutation of a mutant allele back to the allele from which it arose (usually WT)

polygenic

the variation in most phenotypic characters is thisbased on several or many different genetic loci

homeotic mutations

redirect the development of one body segment into another (regulation of gene expression!)

additive inheritance

if heterozygotes phenotype is precisely intermediate between the homozygotes

pleiotropic mutations

affect more than one character

karyotype

description of its complement of chromosomes (number, size, shape, and internal arrangement)

aneuploid

unbalanced chromosome complement (often inviable or fails to develop properly)

polyploidy

changes in teh number of whole sets of chromosomes (more than 2 entire sets of homologous chromosomes)

autopolyploids

arisen by the union of unreduced gametes of the same species

allopolyploids

arisen by hybridization between closely related species

inversion

rearranged gene order from a loop and cross over

pericentric vs paracentric

pericentric = inversion that includes centromereparacentric = inversion that does not include centromere

reciprocal translocation

two nonhomologous chromosomes may exchange sengemnts by breakage and reunion

acrocentric vs. metacentric chromosomes

acrocentric = centromere near one endmetacentric = centromere in middle

fusion of chromosomes

two nonhomologous acrocentric chromosomes undergo reciprocal translocation that they are joined into a metacentric chromosome

fission of chromosomes

metacentric with acentric??? pg. 211

environmental variance

environmentally induced variation among individuals

maternal effect

effects of a mother on her offspring not from the gnes but to nongenetic influences (yolk in egg, maternal care, physiological condition of berthing)

epigenetic inhereitance

when phenotypic differences not based on DNA sequence differences are transmitted among generations of dividing cells in multicellular organisms and also sometiems from parents to offspring (like DNA methylation)

norm of reaction

variety of different phenotypic states that can be produced by a single genotype under different environmental conditions

common garden

offspring of phenotypically different parents can be reared together in a uniform environment

Hardy Weingburg Equillibrium assumptions

1. mating is random (panmictic)2. population is infinitely large (no genetic drift)3. genes are not added from outside the population (no gene flow)4. genes do not mutate from one allele state to another (no mutation)5. all individuals have equal probabilities of survival and of reproduction

gene glow

mating among different populations (migration)

polymorphism

presence in a population of two or more variants (alleles or haplotypes)

monomorphic

locus/character that is not polymorphic

inbreeding depression

inbreeding increases the proportion of homozygotes - mroe likely to get homozygote recessive (bad)Therefore, decline in components of fitness (survival, fecundity)

linkage disequilibrium

association/correlation between specific allels at two loci

linkage equilibrium

no such association between specific alleles at the two loci

quantitative variation

continous/metric varaition - fits a normal distribution

polygenic

due to variation in phenotype

sympatric vs. parapatric vs. allopatric

sympatric = if distinct populations have overlapping geogrphic dddistributions so that they occupy the same area and frequently encounter each otherparapatric = populations with adjacent but nonoverlapping ranges that come into contactallopatric = populations with spearated distributions

Bergmann's Rule

body size increases iwth increasing latitude

cline

gradual change in a character or in allele frequencies over geogrpahic distance

ecotypes

phenotypes that are associated with a particular habitat, often in a partchy mosaic pattern

random walk

random fluctuation of alleles - p will eventually wander (drift) to either 0 or to 1 (no stabilizing force)

hitchhiking

a genotype would increase rapidly in frequency because of linkage to an advantageous mutation that had ocurred at another locus

preadaptation

feature that fortuitously serves a new function

exaptations

preadaptations that have been co-opted to serve a new function

overdominant

when the heterozygote is said to be dominant

underdominant

if heterozygote has lowest fitness

Stabilizing selection

intermediate phenotype is fittest

directional selection

if one extreme phenotype is fittest

diversifying (disruptive) selection

if two or more phenotypes are fitter than the intermediates

coefficient of slection

(s) the amount by which teh fitness of a genotype differes from teh reference genotype (1-w)intensity of selection agaisnt the less fit genotypeselective advantage of the fitter genotype

balancing selection

selection that maintains polymorphism

factors responsible for variation

1. recurrent mutation producing deleterious alleles subject to weak selection2. gene flow of locally deleterious alleles from other populations in which they are favored by selection3. seletively neutrality (genetic ddrift)4. maintenance of polymorphism by natural slection

antagonistic selection

opposing forces acting on polymorphisms - usually does not maintain polymorphisms

inverse frequency dependent selection

the rarer a phenotype is in teh population the greater its fitness

positive frequency dependent selection

the fitness of a genotype is greater the more frequent it is in the populationwhichever allele is initally more frequent will be fixed

selective sweep

reduction/elimination of DNA sequence variation in teh vicinity of a mutation that has been fixed by natural selection relatively recently