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15 Cards in this Set

  • Front
  • Back
Population/ gene pool
population=individuals of same species in same area
gene pool=all the alleles in a population
allele frequencies
Calculation of allele frequencies
-risk of heritable disease
-important for study of evolution
=allele frequency changes in a population
-nonrandom mating
-genetic drift (small pop.size)
-natural selection
Hardy-Weinberg Equation
to predict allele and genotype frequencies in a population

freq of dominant allele (A)=p
freq of recessive allele (a)=q

freq of homozy.dominant (AA)=p^2
freq of heteroz (Aa)=2pq
freq of homozy recessive (aa)=q^2

p^2 + 2pq + q^2= 1
=gene flow between 2 previously isolated populations
rapidly changes allelic frequencies
create new alleles
most have harmful effects
occasionally increase biological fitness
Natural Selection
Resource limitations: prevent exponential pop.growth; lead to competition
Differential reproductive rates (due to heritable variation)
Those w/ "advantageous" traits survive and reproduce
Heterozygotes Advantage
maintains recessive deleterious alleles in population
ex.Malaria/sickel cell, PKU/fungal infection, cystic fibrosis/diarrheal diseases, diabetes/famine
Genetic Drift
changes in allele frequencies due to chance.
ex. Founder effect (amish of lancaster)
Population bottleneck
Human evolution
Hominoids= 22-32 mya (ancestral to humans and apes)
Hominids= 4 mya (ancestral to humans only)
Homo Habilis= 2.3 mya (first hominid to make/use stone tools)
Homo Erectus= 2 mya to 400,000 ya (tools-hand axes, fire; separated from africa to asia)
Homo Sapiens= 130,000 ya
Molecular Evolution
fewer differences b/w a gene or protein sequence in 2 species the more closely related the species are presumed to be
Important differences
Hairiness: nonsense mutation in keratin gene
Fetal hemoglobin: lengthens fetal pd. and maximizes brain growth
comparing Protein sequences
Cytochrome c (cellular resiration)..human and chimp cyt c is identical; human and pigeon differe by 12 aa
HOX genes (control order in which genes get turned on during devt) similar # and function in closely related species
Molecular clocks
estimate time elapsed since 2 species diverged from same ancestor (based on DNA or protein sequence)
Parsimony analysis: simple, method w/ fewest steps is most likely.
Mitochondrial Eve
Replacement hypothesis: all humans evolved from single lineage in Africa (most accepted)
Multiregional hypothesis: human traits originated in several places