Chapter 20 Flashcards
(9 cards)
CC sources of variation
Phenotypic Variation
Mendelian Traits:
Some phenotypes are either “on” or “off” (B or b)
Genetic Variation
Sexual reproduction= recombination; does not create new alleles!
Mutations = only source new alleles
Apply Hardy Weinberg equation
P + Q = 1
P = 0.5 Q = 0.5
Probability of WW offspring = p x p = p^2
Probability of Ww offspring = 2(p x q) = 2pq
Probability of ww offspring = q x q = q^2
Since total frequency of birds must = 1 → p^2 + 2pq + q^2 =1
Requirements of Hardy Weinberg equation
In a population, five conditions must be met to maintain Hardy-Weinberg equilibrium
- No mutations
- Random mating
- No natural selection
- A very large population
- No gene flow between populations
SEQ, CC, HD major mechanisms of evolution (5)
Mutation
Non-random mating
Natural selection
Genetic drift
Gene flow
Mutation
Changes in DNA sequence.
Source of genetic variation, leading to new genes and alleles.
Only mutations in gametes can be passed to offspring.
Silent Mutations: Do not alter function.
Non-random mating
Occurs when mate choice is influenced by genotype (e.g., preference for certain traits).
Consanguineous Mating: Mating between closely related individuals increases the risk of genetic problems in offspring
Natural selection
Major mechanism of evolution, leading to adaptation.
Acts on phenotype, causing changes in allele frequencies in the gene pool.
Requires genetic variation in a population.
Genetic drift
Random changes in allele frequencies, especially in small populations.
Bottleneck Effect: A drastic reduction in population size leads to loss of alleles.
Founder Effect: A small group from a larger population starts a new population, leading to limited genetic diversity.
Gene flow
Movement of alleles between populations through migration of individuals or gametes.
Increases genetic diversity between populations.
