Basic Evolutionary Genetics Flashcards
Why did people who had unprotected sex with those infected with HIV not get the virus?
“broken” CCR5 gene (loss-of-function allele at CCR5 locus = no doorknob)
The CCR5 is a ______ protein found on ____
trans-membrane protein found on CD4+ Helper T-cells
HIV virus has ____ form(s) and they are ____ and _____
2 formsM-formT-form
M-form of HIV is found
early during infection
T-form of HIV is found
later during infection (along with M-form)
M-form requires ____ to enter a CD4+ H T-cell
CCR5
The cells without a “door knob” were immune to ____ form but not ___ from of HIV
M form but not T form
What is the downside to having no CCR5? (homozygous for deltaCCR5 gene)
More prone to other infections, T-cells not as strong (aka prone to west-nile virus)
Evolution via natural selection
non-random differential reproduction of genotypes due to differences in their associated phenotypes
Darwinian Fitness is
the measure of differential reproduction of genotypes
Individual fitness is…
the number of genome copies an individual leaves in the next generation
polygenic traits
characters that are controlled by many genes at once
quantitative traits
polygenic traits
Selection on polygenic traits can lead do
very rapid evolution
Heritability
the proportion of phenotypic variation due to genetic variation (all among individuals)
What contributes to variation
Nutrition (environment) and genes
When the slop of a heritability graph is 1 there is ____ heritability which means…
perfect heritability which means all variation due to genetic variation
In When the slop of a heritability graph is 0…
there is no heritability
R value depends on which variable?
hertability (h^2)
whats the max and minimal response of h^2
1 and 0
Sexual selection is
struggle between individuals of one sex for possession of the other
The tradeoff for fedcundity is
survival
response differential is
change over time
intrasexual hypothesis is what and indicates what trait?
competition with other malesaggression and intimidation
intersexual hypothesis includes what? and describe their properties
good genes-better physical attributematerial benefits- good providersensory exploitation - female attractionsexy sons-male with great genes makes great sonsintersexual conflict
the sexy sons trait creates what in the future populations
dominance of the trait
describe the attributes of sexual conflict
-predation increases-STDs-seminal fluid can have negative effects -resistance exchange of traits
In a trait graph the cost of a better gene =
how much more exposure to danger
in trait graph dotted line is
benefits with mates
in trait graph equilibrium point is the balance betwwen
of sexual and survival selection
M=
ability to provide resources (material benefits)
What leads to the lowering of Darwinian fitness?
Traits that reduce survival
Altruism
a trait that increases the fitness of others but reduces their own
Altruism ultimately leads to a D.fitness of
zero
What is kin selection?
reproductive success that is driven by augmenting the fitness of relatives
In order for kin selection to happen
an indv. needs to be small relative tot he degree of relatedness and benefit to the relative
What is Hamilton’s Rule?
C<R*B
What is “C” in Hamilton’s rule?
fitness coast of altruistic trait
R in Hammys rule?
relatedness
Values for R in relatedness
1/2 son-daughter1/2 brother sister1/4 grandchild1/8 1st cousin
In kin selection/altruistic conditions, the offspring ______ to the fitness of the parents
add
As long as Hammies Rule works then _____
kin selection is present
What is the positive feedback loop?
cycle of adaptation & counter-adaptation
Coevolution is when
two species evolve together/interchangeably
Two types of coevolution
interspecificintraspecific/intergenic
Interspecific coevolution is
two speices evolve in response to each other
intra/intergenic coevolution is
two GENES in the genome of the SAME species evolve in response to each other
The two forms for each type of Coevolution is
antagonisticmutualistic
Describe antagonistic interspecific coevolution and what is the “main name” for that
one species targets another and then the other evolves to adapt; “Red Queen”
mutualism can turn into parasitism if a species
“cheats”
the “cheater allele does not accumulate in the gene pool because
the affected species “penalizes” the cheater gene in one way or another
Describe antagonistic intra/intergenic situation
sperm and egg; lysin and egg matrix
T/F: Lysin is one of the most rapidly evolving genes
True
Describe mutualistic intergenic/intraspecific situation
insulin and insulin-receptor gene
The common sexy ratios found in nature and rareity
100% female (asexual; very rare)mostly female (rare)50/50 male to female (normal)
Mostly female indicates what type of breeding
inbreeding
50/50 male-female indicates what type of breeding
outbreeding
T/F: sex ratio is completely controlled by Mendellan segregation of sex chromosomes
FALSE
Percentage difference of male and females can also be due to
organisms interaction and response to the envrionment
To understand sex ratio evolution we need to look at what level of offspring?
grand-offspring
What is the fitness for grandoffspring?
grand-offspring/4
When there is a bias in the sexy ratio, the greater fitness is achieved by the
rarer sex
For random mating, all sex ratios eventually lead to
50/50
What is the effect of limited space to reproduce on offspring grow together
inbreedinghigher female ratio due to more grand-offspring
The more male biased a population the ___ the grand-offspring
lower
In the sex ratio theory, the maximum of grand offspring is reached:in a 50/50 ratio when ___in a inbreeding ratio when ___
the rare sex is producedif more females are produced
Species are
groups of individuals that exchange hereditary material under natural conditions
Reproductive Isolation Mechanisms (RIMS) are
ways that allow separate species to develop
Post - zygotic RIM
offspring are produced but are sterile or die before reproductive maturity
Pre-zygotic RIM
When species don’t even mate or get to produce a zygote (lock and key analogy)-behavior-anatomy-physiology
Behavioral isolation also involves what preference?
habitat
2 types of geographical speciation
AllopatricSympatric
Describe allopatric
species are physically isolated from one another and they develop differently into a whole new species
Describe sympatric
all species are together in one place, with no physical barrier to genetic exchange
T/F: There is a method of direct selection for reproductive isolation
FALSE; species don’t encounter one another
Allopatric speciation leads to what type of isolation? Why?
pre-zygotic, because the species develop different BPM attributes that prevent mating
What is positive assortative meeting
when individuals with similar phenotypes/preferences mate and “assort” the species more
reproductive isolation (pre-zygotic isolation-alloppatric speciation) leads to what type of mating?
positive assortative
Why does (+) assortative mating (pre-zygotic isolation) lead to speciation?
it leads to pleiotropy
What is pleiotropy
the same gene has multiple phenotypic effects
Pleiotropy can lead to what type(s) of isolation?
both pre-/post-zygotic isolation
Speciation in allopatry can ALSO occur in sympatry due to
pleiotropy (mating preference)
What is disruptive selection?
natural selection that favors 2 phenotypes at opposite extremes
Philopatry
offspring returning to where their parents mated
T/F: Philopatry can also lead to reproductive (pre-zygotic-positive assortment) isolation
True!
To get a 50% chance of philotropy what must occur?
Random mating
What leads to 100% of offspring returning to parents mating ground?
CompletephilopatryPerfect postitive assortmentcomplete pre-zygotic isolation
no philpatry = ( in terms of philopatry)
no pre-zygotic isolation
Philopatry is an example of what speciation
sympatric
When determining phylogeny through changes in bases, start off by
finding how many changes in bases there are relative to the outgroup and then order from least to greatest
