Conservation Genetics:Phenotypic variation in natural populations

FW4301

Genetics

the study of differences among individuals

What does inheritance rely on?

comparing progeny/parents to unrelated individuals

What is variability essential for?

adaptive revolutionary change

Discrete Variation

binary factor, yes or no (black and white)

~you’ve either taken genetics or you haven’t

Continuous Variation

variable

~height, many options, controlled by more than one gene (polygenic)

Why is Mendel problematic?

• Selected traits with discrete categories (tall vs dwarf)

• Success came from ignoring continuous quantitative variation

• Goal: solution to the ‘evolution of organic forms’

The Molecular Evolution

• Pre-1960s: dominated by laboratory drosophila studies

• 1960s: biochemical techniques allowed studying any wild organism

• Today: whole-genome sequencing (Earth BioGenome Project)

Polymorphism

• 2 or more discrete, genetically based phenotypic traits

Examples of Polymorphism

• Ex.) Snail Shell Color:

• Ex.) Arctic Skua Plumage

Transposons

little pieces of DNA that have copied itself around the genome. They are like the replicated chorus of a song. Most of them don’t do anything for you, they really just take up space

What is MC1R

gene responsible for color in birds, mammals, and extinct mammoths

Common target for adaptive evolution across taxa

What is morphology caused by

Caused by both genetic (Vg) and environmental (Ve) factors

Morphology equation

• Equation: Vp = Vg + Ve

  • Vp: total phenotypic variability

  • Important for understanding the limits of selection

Partitioning Phenotypic Variance

The heritability of a trait is defined as the proportion of the total phenotypic variation that has a genetic basis (VG/VP). The greater the heritability of a trait, the more phenotypic differences among individuals within a population are due to genetic differences among individuals.