Flashcards in Population and Genetics Deck (19):
who is Malthus? what was his theory?
Left unchecked, human reproduction rates will rapidly outpace resource production, leading ultimately to “crime, disease, war, and vice.” (these being “natural” checks on population growth)
At the point where population size outstrips resource production, there are only two alternatives: find the means to expand the resource pool, or DIE
which organisms survive?
which organisms survive has to do with interactions among organisms, and between organisms and their environment
genotype and reproduction
genotype governs reproductive output and effects competitive ability
why is determining genotype complicated?
- phenotype may be similar for different genotypes
- environment effects may interfere with expression
- multiple genes may be implicated in a single phenotype
what happens when a population is in hardy-weingberg equilibrium?
the population is not evolving
what happens when a population is no longer in hardy-weinberg equilibrium?
no evolution because no charge in allele frequency!
other than a test cross, what's another way to asses the genotype of an organism? what's the equation?
models of population genetics
p+q = 1
p^2 + 2pq + q^2 = 1
what is p?
the frequency of the dominant allele
what is q?
frequency of the recessive allele
what is 2pq?
frequency of homozygous allele Aa
what is p^2?
frequency of AA
3/8 = .375 p^2
what is q^2?
frequency of aa
2/8 = .25 q^2
what happens to genotype frequencies in the absence of selection?
they'll go to Hardy-Weinberg equilibrium
what are the four assumptions of Hard-Weinberg?
1) mating is random
2) no natural selection
3) large population size
4) mutation and migration negligible
what could cause the relative frequency of alleles to change?
new allele and phenotype will appear in subsequent generations
why does HW equilibrium require no selection?
so all offspring have an equal chance of survival and reproduction
why does HW equilibrium require large population size?
because random events will have a large impact on small populations
a storm destroys 80% of the habitat and its inhabitants --> even if a population regains its original size, relative proportions of species are changed irrevocably
why must there be no migration or mutation for HW equilibrium?
no new alleles