Chapter 14,16,17 Flashcards
Abosolute dating
age of fossils is estimated by radioactive decay
Relative dating
position of fossil in sedament
Homologous structures
diffrent apperance and functions that derived from the same body part in a common ancestor( fingers in mamals)
Analogous structures
Serve similar structures-evolved independantly
Vestigial structures
no apparent function but resemble structures their ancestors had (blind cave fish- nonfunctional eyes)
natural selection
Individuals with superior physical or behavioral characteristics are more likely to survive and reproduce than thoes without such characteristics.
‘Ingrediants’ for natural selection (5)
selective pressure, reproduction, desirable characteristics, variation, heritable
importance of Hardy Weinberg in populations
If a population is not in HW it indicates that one or more of five mechanisms is acting on the population.
Agents of evolutionary change (5)
Mutation (variation), Gene flow ( allele movement between populations), Nonrandom mating (Assorative/disassorative mating), Genetic drift- Founder affect (changes allele frequency), Selection (natural/ artificial)
Assortative mating
increases homozygots, selects parteners based on specific traits
Disassorative mating
phenotypically diffrent individuals mate, produce excess of heterozygots
Hardy Weinberg assumptions (5)
No mutation takes place, No genes are transfered to or from other sources, random mating is occuring, large population size, no selection occurs
Hardy equation
p= individuals homozygous for first allele 2pq= individuals heterozygous for both alleles q= individuals homozygous for second allele p+q=1
Stabilizing selection
Favors intermidiates ( human birth weight)
Disruptive selection
Favors extremes over intermidiates ( birds with very large or small beaks)
