Ecological Genetics

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Ecological Genetics by Mind Map: Ecological Genetics

1. What is Ecological Genetics?

1.1. Genetics of ecologically important traits

1.1.1. survival

1.1.2. reproduction mating success offspring

1.2. Study of the process of phenotypic evolution occurring in present day populations

1.2.1. Darwin's explanatory model of natural selection (Mayr) Observation 1: Every population has such high fertility that its size would increase exponentially if not constrained. Observation 2: The size of populations, except for temporary annual fluctuations, remains stable over time Observation 3: The resources available to every species are limited Inference 1: There is intense competition (struggle for existence) among members of a species Observation 4: No two individuals of a population are exactly the same Inference 2: Individuals of a population differ from each other in the probability of survival (i.e., natural selection) Observation 5: Many of the differences among individuals of a population are, at least in part, heritable Inference 3: Natural selection, continued over many generations, results in evolution

1.2.2. Mechanisms of evolution Mutation Drift Gene flow Selection

2. Population genetics

2.1. Goals

2.1.1. To explain the origin and maintenance of genetic variation

2.1.2. To explain the patterns and organization of genetic variation

2.1.3. To understand the mechanisms that cause changes in allele frequency

2.2. Statistical tests

2.2.1. Chi-squared test X^2 = Sum[(observed - expected)^2 /expected ] degrees of freedom = number of classes of data - number of estimated parameters - 1 p-value = probability that the result occurred by chance Typically use an alpha of 0.5 for significance tests For deviations from H-W, degrees of freedom = 1 and the cut-off for significance is when X^2>~=3.84

2.3. Hardy-Weinberg equilibrium

2.3.1. Summary statistics p + q = 1 p = (2n_AA + n_Aa) / 2n q = (2n_aa + n_Aa_Aa) / 2 (p + q)^2 = p^2 + 2pq + q^2 = 1 P + H + Q = 1 P = p^2 Q = q^2 H = 2pq p = P + H/2 q= Q + H/2

2.3.2. Assumptions diploid, sexual, discrete generations allele frequencies are the same in both sexes Mendelian segregation random mating no mutation no migration no drift (implies very large populations) no selection

2.3.3. Derivation through potential matings through cross multiplication

2.3.4. Outcomes Populations in equilibrium after 1 generation At intermediate allele frequencies, heterozygotes are more common Below a frequency of ~0.1, nearly all of the corresponding alleles are found in heterozygotes

2.3.5. exercise

2.4. Deviations from H-W

2.4.1. Nonrandom mating Inbreeding increases homozygotes, decreases heterozygotes affects all loci equally inbreeding coefficient Assortitive Mating positive negative Do inbreeding or assortative mating result in evolution?

2.4.2. Mutation types deletions insertions chromosomal rearrangements duplications point mutations polyploidy changes in allele frequencies rate at 10e-4 to 10 e-6 per generation in mitochondria...10e-8 to 10e-10 in nuclear DNA forward reversible

2.4.3. Migration island model p_i,t = p_i,t-1 (1-m) + bar_p m

2.4.4. Drift

2.4.5. F-statistics

2.4.6. Selection

2.4.7. Interactions amongst evolutionary forces

3. Quantitative genetics

4. Adaptation

4.1. A phenotypic trait that has evolved to help an organism deal with something in its environment

4.2. Which of the four evolutionary mechanisms lead to adaptation?