Chapter 25 Flashcards
microevolution
evolutionary changes within populations of species
macroevolution
evolutionary events leading to the emergence of new species and other taxonomic groups
gene pool
the genetic information carried by members of a population
population
a group of individuals belonging to the same species that live in a defined geographic area and actually or potentially interbreed
Hardy-Weinberg Law
- describes what happens to allele and genotype frequencies in “ideal” populations
- p^2 + 2pq + q^2 = 1
Hardy-Weinberg Assumptions
- No selection
- No mutations
- No migration
- Infinitely large population
- Random mating occurs
Hardy-Weinberg Consequences
- Dominant traits do not necessarily increase from one generation to the next
- Genetic variability can be maintained
- Frequencies of other genotypes can be calculated
HIV-1 Gene
CCR5
What causes changes in allelic frequencies?
Migration and Mutation
Genetic drift
- significant random fluctuations in allele frequencies in small populations
- Possible by chance alone
- degree of fluctuations increases as populations size decreases
- Founder & Bottleneck effect causes genetic drift
Natural selection
Individuals with adaptive traits product more offspring
Inbreeding increases the proportion of ___ in a population.
homozygotes
Average time for speciation
100k - 10m years
Molecular clocks
- measures rate of evolutionary change
- measured in terms of amino acid or nucleotide sequences; evolutionary changes accumulate at constant rate over time
