Exam 2 Flashcards
horizontal gene transfer
genes transferred organism to organism but gen to gen
batesian mimicry
harmless species resemble harmful species, getting protection from predators
Why do primates with full color vision have so many fossilized genes for olfaction?
with such great vision smell was not use das much causing them to lose that trait and fossilizing the gene
pleiotropy
condition when a mutation in a single gene affects the expression of more than one different phenotypic trait
what impact do mutations alone have on selection?
mutations inject new alleles into gene pools and change the allele frequency. once a new mutation arises, drift and selection may begin to act on them
What do selection coefficient values tell you?
the strength of selection and whether or not a genotype if favored
indels
-insertion or deletion of bases in the genome of an organism
genetic drift
change in frequencies of allele copies in population resulting from sampling error in drawing gametes from gene pool to make zygotes and from chance variation in the survival and or reproductive success of individuals
population genetics
study of the distribution of alleles within population and the mechanisms that can cause allele frequencies to change over time
examples of postzygotic reproductive isolation
- hybrid sterility
- low fitness
reinforcement
results when any hybrid offspring has low fitness and natural selection results in assortative mating and prezygotic isolation
deletion
a base pair is deleted out of genome
ex: cleft palate, heart defects, autoimmune disease
null hypothesis
original negative hypothesis
most mutations are
neutral and random
selection coefficient
measure of the extent to which natural selection is acting to reduce the relative contribution of a given genotype to the next generation
sympatric speciation
populations in the same geographical area
bottleneck
reduce genetic variation, causes genetic drift and rare alleles are likely to be lost
point mutation
at one point there is a change
ex: 6 fingers, finger fusion, skeleton calcification, albinism
morphospecies strengths and weaknesses
s:
- primairy way fossils are assigned to a species
w:
- works badly for fungi, bacteria and archea
- cant tell species age vs. diff species
negative frequency dependent selection example
elederflower orchids
2 distinct morphs to trick pollinators
more common color=lower fitness
postzygotic reproductive isolation
hybrid offspring are sterile
When does inbreeding have a minimal impact?
when there is a dominant allele present to mask the deleterious recessive allele
barriers that make allopatric speciation possible
- ocean
- mountains
- distance
- rivers
selection. vs. drift
selection occurs when genotypes differ in fitness
- drift= small pop
- selection=large pop
prezygotic reproductive isolation
divergence in traits between populations that prevent fertilization from occurring
Hardy weinberg assumptions
- popualtion is always large
- all geneotypes at a locus are equally likely to survive and reproduce
- no alleles enter or leave the population
- no mutation because that wouled lead to new alleles
speciation
new species arise, one evolutionary lineage splits into 2 or more
secondary contact
hybridization between two parental forms of a group that were previously separated
relative fitness
success of the genotype at producing new individuals standardized by the success of other genotypes in the population
phylogenetic strengths and weaknesses
s:
- works on sexually and asexually reproducing plants, fossils and some prokaryotes
- species identification based on statistically significant difference in traits
w:
- gene sequencing is expensive
- evolution is on going
what is hetero superiority?
when the hetero genotype is favored above either homo genotype
- can allow deleterious alleles to persist
smaller sample=
more sampling error
inbreeding depression
reduction in the average fitness of inbred individuals relative to that of outbred individuals
phylogentetic species concept
monophyletic based on comparison with other populations
When is hetero favored vs homo
Sickle cell in hetero is favored when malaria is present
genetic load
burden imposed by the accumulation of deleterious mutations
genetic locus
refers to the specific location of a gene or piece of DNA sequence on a chromosome
fitness
success of an organism to survive and reproduce
missouri collared lizards and Illinois prairie chicken
- actions to prevent extinction?
- genetic problems?
- brought in others from a separate population to reproduce with the endangered population
- increase variation
- prevent bottleneck
What is fixation and when does it occur?
carried by all members of the population, no genetic variation at that locus
- small population due to genetic drift
Hardy weinberg conclusions
- allele frequency in a population will not change
- if the allele frequencies in a population are given by p and q the genotype frequencies will be given by p2, pq and q2
evolutionary trade-offs
choice must be made bewteen multiple things that are incomaptible or an increase in one might lead to a decrease in another
theorems
mathematical statements that have been proven based on previously established theorems or axioms
average excess of fitness
the difference between the average fitness of individuals bearing the allele and the average fitness of the populations as a whole
evolutionary arms race
species interact antagonistically in a way that results in each species exerting reciprocal directional selection on the other
How can coevolution function as the engine for biodiversity?
increase in genetic diversity caused by the heterogeneity of coevolutionary processes across the range of ecological patterns
morphospecies concept
species designation and identification is based on morphological differences between species
what happens if hardy weinberg assumptions are violated?
- mutation
- migration
- drift
- change in allele frequencies
Why does inbreeding depression arise?
rare recessive alleles become expressed in a homozygous state where they can detrimentally affect the performance of individuals
Hardy weinberg conditions
- no mutation
- no selection
- no migration
- no genetic drift
- random mating
endosymbionts
mutualistic organism lives within the body or cells of another organism.
ex: microbe live in the digestive tract of mammals to aid in digestion
genetic drift problems
- loss of hetero
- reduces variation
- more error
- bottleneck and founder effect
antagonisitic pleiotropy
a mutation with beneficial effects for one trait also causes detrimental effects on another trait
isolation by distance
pattern in which populations that live in close proximity are genetically more similar to each other than populations that live further apart
When does hybridization result in either reinforcement or speciation?
fertile hybrid can lead to new species
if its not successful reinforcement will occur
negative frequency dependent selection
when rare genotypes have higher fitness than common genotypes
biological weakness
w:
- doesn’t work for fossils/elephants
symbionts
mutually beneficial relationship between two
extinction vortex
small population resort to inbreeding and genetic drift, leading to a loss of genetic variability
biological species concept
inbreeding natural populations that are reproductively isolated
mutualists
alleles favored for selection benefit rather than harm
- ex: long tongue fly eating flower nectar and passing pollen off to next flower
allopatric speciation
populations are in separate non overlapping geographical areas
coefficent of inbreeding (F)
the probability that the two alleles at any locus will be identical because of common decent
“use it or lose it”
use a trait or it will fossilize because its no longer needeed
mullerian mimicry
several harmful species resemble each other, learned avoidance of predators
problems and benefits of inbreeding
- in large populations rare recessive alleles can be preserved even if they’re deleterious because more common dominant alleles overshadow them
- rare deleterious alleles can be unmasked in homo because its more likely to have the same gene
gene duplication
a gene duplicates
ex: down syndrome
examples of prezygotic reproductive isolation
- mechanical isolation: incompatible genitalia
- behavioral isolation: different dances
- temporal isolation: mate at different times of year
- game incompatibility: gametes fuse but zygote dies
antagonists
generate negative frequency-dependent selection on each other
ex: Newts TTS, garter snakes get resistance to it, but Newts get more TTS
genetic drift results from…
sampling error
inversion
chromosome pops apart rearranges and goes back together
ex: hunter syndrome
founders effect
new populations started by a smaller number of people, causes genetic drift
population size and mutation impact
small population= larger mutation impact
somatic mutation
- affects cell in the body of an organism
- not heritable
collapse of a dynasty
- Hapsburgs marry within extended family
- 1st cousins marry
- charles was so inbred he was infertile
- only half of children lived to be 1
cryptic species
Species look alike but are genetically different
sampling error
a small subset of the genetic diversity of the source population is likely to be included in the new population. and the relative freqeuncies of these alleles may be very different from what they had been before
insertion
a base is inserted into the genome
ex: huntingtons disease
germ-line mutations
- affect gametes
- heritable
- relevant to evolution
