Population Genetics

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Slide 1

Population Genetics

Slide 2

The Gene Pool

Members of a species can interbreed & produce fertile offspring

Species have a shared gene pool

Gene pool – all of the alleles of all individuals in a population

Slide 3

The Gene Pool

Different species do NOT exchange genes by interbreeding

Different species that interbreed often produce sterile or less viable offspring e.g. Mule

Slide 4

Populations

A group of the same species living in an area

No two individuals are exactly alike (variations)

More Fit individuals survive & pass on their traits

Slide 5

Speciation

Formation of new species

One species may split into 2 or more species

A species may evolve into a new species

Requires very long periods of time

Slide 6

Modern Evolutionary Thought

Slide 7

Modern Synthesis Theory

Combines Darwinian selection and Mendelian inheritance

Population genetics - study of genetic variation within a population

Emphasis on quantitative characters (height, size …)

Slide 8

Modern Synthesis Theory

1940s – comprehensive theory of evolution (Modern Synthesis Theory)

Introduced by Fisher & Wright

Until then, many did not accept that Darwin’s theory of natural selection could drive evolution

S. Wright

A. Fisher

Slide 9

Modern Synthesis Theory

TODAY’S theory on evolution

Recognizes that GENES are responsible for the inheritance of characteristics

Recognizes that POPULATIONS, not individuals, evolve due to natural selection & genetic drift

Recognizes that SPECIATION usually is due to the gradual accumulation of small genetic changes

Slide 10

Microevolution

Changes occur in gene pools due to mutation, natural selection, genetic drift, etc.

Gene pool changes cause more VARIATION in individuals in the population

This process is called MICROEVOLUTION

Example: Bacteria becoming unaffected by antibiotics (resistant)

Slide 11

Hardy-Weinberg Principle