Midterm 1 (Part 2) Flashcards
What is negative frequency dependance?
directional selection for a phenotype is stronger when the phenotype is less common, this is one form of balancing selection
What traits are needed for natural selection to occur
individuals vary in a trait, there is association between trait and success, trait is heritable
What is inbreeding avoidance?
Kin recongnition, dispersal, delayed maturation, self-incompatability , etc
What are Mendels 3 laws?
Law of segregation: 2 allelles for each gene per gamete
Law of indep. assort.: inheritance of one gene doesnt affect inheritence of the other
Law of dominat: one allele is dominant and expressend
What is genetic drift?
finite populations are subject to random changes in allele frequencies across generations due to chance , occurs due to sampling variation
What is germ plasm theory?
proposed that genetic info tramistted by germ cells in gonads, all other cells dont transit genetic info
Impacts of mutations?
delterious (reduce fitness) or beneficial, can be neutral which creates neutral genetic variation in a population
A cross between monohybrids…
monohybrid cross (between hetero. individuals)
Why is there inbreeding in agriculture?
so genetic variation is lost and a single genotype is fixed
What is relative fitness
individuals contribution to next generation relative to that of other individuals
What can cause inbreeding depression? (2)
dominance hypo- deletrious alleles tend to be recessive
heterozygote advantage- some hetero have higher fitness that homozygote
6 HW assumptions?
Dipliod locus reproduce sexually, random mating, no nat. selection, no mutattion, no migration, no genetic drift
What is a population bottleneck?
rapid decrease in pop size which reduces variation and enhances genetic drift
What does it mean if allele has a plus?
more common and likely dominant
How does quantitative variation arise?
many loci can affect the trait, enviroment also affects expression of the trait
what is outbreeding?
mating between individuals who are less related than would be expected by random mating, increases heterozygosity, increase in fitness over non outbred individuals (heterosis)
What does inbreeding cause?
increase in frequency of homozygotes across genome, deviation from HW, decrease in fitness called inbreeding depression
What makes a event independant?
outcome of one has no affect in outcome of other
2 features of HW principle?
1- certain conditions, there is a predictable relationship between allele and genotype frequencies in a population
2- Medilian inheritence does not alter allekle frequencies in abscene of evolutionary processes
preservation of genetic variation?
from mutation, by balancing selection, mutation drift slection balance, spatial variation
what is positive frequency dependence
direction selection for phenotype stregthens as phenotype becomes more common
what is a population?
group of individuals that live in same area and interbreed
What did mendel propose?
a model where heredity was controlled by factirs, each individual gets one factor from their parent- factors now known as genes, was partially correct
4 issues with mendels laws?
complete dominance is far from universal, allelles dont always segregate equally (50:50), assortment of alleles at one locus is not independant o fother locuses, inheritence patters are more complex
Biometricians vs Mendelians:
B- continous traits, thought evolution happened slowly with no large jumps
M- discrete traits, thought sudden dramatic changes in phenotype occured (saltationism)
phenotype vs genotype?
P- quantifiable character of organism (color, size)
G-makeup of alleles it carries (PP, Pp, pp)
Why is mating often non-random?
relatives mate more or less often (inbreeding/outbreeeding), self fertilization, may mate with ppl more or less similar by chance
What is blending inheritance?
Phenotypes in offspring are average of parents, was argued this is ineffective because variation is lost
what is local adaption
Population adapts to local environment, gene flow can hinder as it causes outbreeding depression
What is a founder event?
small group colonizes new geographic area
the probability of recombination between two loci…
Increases as the distance between them increases
What does natural selection act on?
Acts on phenotypes
Who is August Weismann?
evolutionary theorist, not a creationist, agaist lamarks thoeries, developed germ plasm theory
What is random mating?
mate randomly with respect to the genotype at locus of interest, sometimes called panmixia
Mutpilcation rule?
Pr (A & B)= Pr(A) X Pr(B)
what are three forms of selection
linear/ directional, stabalizing, disruptive
Micro vs macro evolution?
change in allele frequency over short periods of time compared to long periods across generations
What contributes to fitness?
survivorship, fecundity, mating success
What is co dominance/ partial dominance
partial (pink flower)
co (white and red flower)
What are alleles and locus/ loci?
L- specific location on chromosone
A- unique variation of gene
What are effects of genetic drift?
causes random change in allele frequency across generations, reduces variation because alleles are lost, causes populations to diverge
What was mendels work?
Used peas, worked with discrete varaibles and used true breeding, crossed P generation to make F1
What is the HW equation?
p^2 + 2pq +q^2 =1
As the number of loci increases…
phenotypic variation becomes finley graded (skin colors)
Ex. of small/large scale mutations
Substitutions, intersetion, deletion, or large scale like translocations, chromosne loss or gain
Parts of germ plasm theory?
germ cells produce somotic cells, germ cell not disposable, in plants corals and sponges soma produce germ cells and if mutation occurs it affects all future cells
What is gene flow
migration, movement of alleles between populations , greater than affects of mutation because is more frequent
Addition rule?
Pr (A + B)= Pr(A) + Pr(B) for only one outcome
What is a mutation?
change in genetic info, arises from errors during DNA replication, ultimate source of genetic variation, random in occurrence
What is a gene pool
All copies of each allele at given locus
