Microevolution Flashcards
microevolution def
changes in gene pool of populations over time
gene pool def
all alleles of all genes of all individuals in a population
how is macroevolution different from micro
evolution on a grander scale
major evolutionary events above level of the species
includes speciation
microevolution is within a species
why is population genetics ikmportant
combines darwins theory of evolution with mendel’s theory of inheritance
what does pop genetics say about human pathoegns
bacteria - shows resistance to antibiotics (MRSA)
viruses - resistance to antiviral (HIV)
new pathogens e.g. ebola, corona, influenza (has had many variants e.g. spanish flue, swine flu, bird flu etc.)
covid19 -when was most recent common ancestor?
shown via molecular clock
Nov 2019 - lines up w/ first outbreak in wuhan china
which coronavirus is SARS CoV 2 related to
beta corona viruses
found in bats
how is sars cov 2 related to the virus found in horseshoe bats
96% the same
shows not directly the same as the one in bats, so virus diverged ~ 40-70 yrs ago
why might thalssemia diseases be common in certain areas?
heterzygous form gives resistance to malarial parasite
so its commonality overlaps in places where malaria common
similar to sickle cell’s malarial resistance
importance of pop genetics in wild populations
important to know how much genetic diversity is in population and how it’s distributed
low diversity not good (e.g. in cheethah)
how many genotypes in a single gene locus in diploid organism
3 genotypes: RR, Rr and rr
how do we calculate allele frq?
no. of allele of one type/total no. of alleles
what does p and q represent
p = dominant
q= recessive
how do we calculate genotype frq
no. indivudals of one genotype/total no. individuals
hardy weinburg equilibrium equation
shows the relation between allele frq and genotype frq
p^2 + 2pq + q^2 = 1
p+q = 1 always
what are the conditions that need to be met for the HW equilibrium to be kept
- large population size
- random mating
- no migrating from other pops
- no selection
- no mutation (mutation rate low, but usually not significant unless there’s selection so dw bout it)
what factors could change allele frq
genetic drift (large effects on small pop)
non-random mating - sexual selection
migration - transfer of alleles from one pop to another
selection
how is genetic variation preserved? - natural selection
via balancing selection:
- heterozygotic advantage (e.g. sickle cell and malarial resistance)
- diploidy
- neutral alleles
also diff selective pressures across geographic range of pop = clinal variation
what has lead to lack of genetic diversity and low populations in cheetahs?
poor sperm quality
low fecundity
high susceptibility to infection
what is the mating beh in cheetahs and how was this experimentally shown?
one female will mate with multiple males
DNA samples obtained non-invasively (from their poo) from mother and cubs
did paternity test
found that 43% of litters father by more than one male
mostly the female wouldn’t go back to baby daddy in subsequent years
POLYANDRY - females w/ multiple males
pros and cons of polyandry for female cheethas
cons:
inc risk of predation
meeting aggressive males
higher chance of catching disease
pros:
gives inc genetic diversity in offspring
avoids infanticide (common in other big cats)
why might genetic disease be more common in isolated populations?
founder effects and subsequent genetic drift
deletrious alleles may become more common
effects are more pronounced in smaller populations
what is diploidy
is the harmful allele is recessive, then selection acts on homo recessive genotype only
but the allel stays in the population via the heterozygous form
effectively hidden from selection
