Modern Evolutionary Biology

I. Population Genetics

A. Overview

B. The Genetic Structure of a Population

C. The Hardy-Weinberg Equilibrium Model

D. Deviations From HWE:

1. Mutation

2. Migration

3. Non-Random Mating:

4. Populations of Finite Size and Sampling Error - "Genetic Drift"

5. Natural Selection

1. Fitness Components:

D. Deviations From HWE:

5. Natural Selection

1. Fitness Components:Fitness = The mean number of reproducing offspring / genotype

- probability of surviving to reproductive age - number of offspring - probability that offspring survive to reproductive age

D. Deviations From HWE:

5. Natural Selection

1. Fitness Components:Fitness = The mean number of reproducing offspring / genotype

- probability of surviving to reproductive age - number of offspring - probability that offspring survive to reproductive age

2. Constraints:

i. finite energy budgets and necessary trade-offs:

D. Deviations From HWE:

5. Natural Selection

1. Fitness Components:Fitness = The mean number of reproducing offspring / genotype

- probability of surviving to reproductive age - number of offspring - probability that offspring survive to reproductive age

2. Constraints:

i. finite energy budgets and necessary trade-offs:

GROWTH

METABOLISM

REPRODUCTION

Maximize probability of survival

GROWTH

METABOLISM

REPRODUCTION

GROWTH

METABOLISM

REPRODUCTION

Maximize reproduction

D. Deviations From HWE:

5. Natural Selection

1. Fitness Components:2. Constraints:

i. finite energy budgets and necessary trade-offs:

TRADE OFF #1: Survival vs. Reproduction

METABOLISM

METABOLISMREPRODUCTION REPRODUCTION

Lots of small, low prob of survival

A few large, high prob of survival

D. Deviations From HWE:

5. Natural Selection

1. Fitness Components:2. Constraints:

i. finite energy budgets and necessary trade-offs:

TRADE OFF #1: Survival vs. ReproductionTRADE OFF #2: Lots of small offspring vs. few large offspring

D. Deviations From HWE:

5. Natural Selection

1. Fitness Components:2. Constraints:

i. finite energy budgets and necessary trade-offs:ii. Contradictory selective pressures:

Leaf Size

Photosynthetic potential

Water Retention

D. Deviations From HWE:

5. Natural Selection

1. Fitness Components:2. Constraints:

i. finite energy budgets and necessary trade-offs:ii. Contradictory selective pressures:

Leaf Size

Photosynthetic potential

Water Retention

Rainforest understory – dark, wet

Big leaves adaptive

D. Deviations From HWE:

5. Natural Selection

1. Fitness Components:2. Constraints:

i. finite energy budgets and necessary trade-offs:ii. Contradictory selective pressures:

Leaf Size

Photosynthetic potential

Water Retention

Desert – sunny, dry

Small leaves adaptive

D. Deviations From HWE:

5. Natural Selection

1. Fitness Components:2. Constraints:3. Modeling Selection:

a. Calculating relative fitness

p = 0.4, q = 0.6 AA Aa aa

Parental "zygotes" 0.16 0.48 0.36 = 1.00

prob. of survival (fitness) 0.8 0.4 0.2

Relative Fitness 0.8/0.8=1 0.4/0.8 = 0.5 0.2/0.8=0.25

p = 0.4, q = 0.6 AA Aa aa

Parental "zygotes" 0.16 0.48 0.36 = 1.00

prob. of survival (fitness) 0.8 0.4 0.2

Relative Fitness 1 0.5 0.25

Survival to Reproduction 0.16 0.24 0.09 = 0.49

Freq’s in Breeding Adults 0.16/0.49 = 0.33

0.24/0.49 = 0.49

0.09/0.49 = 0.18

= 1.00

Gene Frequencies F(A) = 0.575 F(a) = 0.425

Freq’s in F1 (p2, 2pq, q2) 0.33 0.49 0.18 = 1.00

D. Deviations From HWE:

5. Natural Selection

1. Fitness Components:2. Constraints:3. Modeling Selection:

a. Calculating relative fitnessb. Modeling Selection

D. Deviations From HWE:

5. Natural Selection

1. Fitness Components:2. Constraints:3. Modeling Selection:4. Types of Selection

Some traits that decrease survival may be selected for because they have a direct and disproportional benefit on probability of mating.

Intrasexual – competition within a sex for access to mates.

Intersexual – mates are chosen by the opposite sex.

D. Deviations From HWE:

5. Natural Selection

1. Fitness Components:2. Constraints:3. Modeling Selection:4. Types of Selection

Sexual Selection

Sources of Variation Agents of Change

Mutation Natural Selection

Recombination Genetic Drift

- crossing over Migration

- independent assortment Mutation

Non-random Mating

VA

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Modern Evolutionary Biology

I. Population GeneticsA. OverviewB. The Genetic Structure of a PopulationC. The Hardy-Weinberg Equilibrium ModelD. Deviations From HWEE. Summary; The Modern Synthetic Theory of Evolution