Lecture 4 - Natural Selection

De-extinction via Genome Extinction

Evolution

• Change in heritable characteristics of biological populations over successive generations.

Natural Selection

• Primary mechanism of adaptive selection - meaning evolution that makes organisms better suited to their environment

• Survival of fittest

• Process takes plave when organisms that are better adapted to their environment have a higher chance of survival and produce more offspring

• Selection on individuals with higher darwanian fittness.

• Adaptive evolution

Speed of Evolution

Requirements for natural selection

Relative fittness and Selection Coefittient

Example of Selection and Fitness

• Start with pale moths more favoured → due to environment black became more favoured → causes the allele frequency to increase dramatically

• Fitness is environmental

Dominance Relations

Overdominance

Four models of selection

Consequences of Selection

Directional Selection

Stabalising Selection

Humans: deviating from birth weight can cause immortality

Disruptive Selection

Darwin Finches: Different species of darwin finches, specialising on seeds or insects, have evolved from original population.

Balancing Selection

What selection pressure best explains phenotypes?

What determines phenotypes?

Phenotypic plasticity

Range of phenotypic traits of a single genotype under varying environmental factors.

Heritability