UNIT 6 - Evolution

9.10.2SWBAT identify other evolutionary

mechanisms of natural selections and compare them with natural selection

What is this bid doing and why?

• http://www.youtube.com/watch?v=8tO80BvZapA

IBE - JTPS

• Have you ever wondered why many male birds, such as cardinals, are brightly colored while females of the same species are dull brown?

J-TPS (Justify –Think Pair Share)

THINK PAIR

SHARE

Natural selection is not the only mechanism through which populations evolve

Mechanisms for evolution

• Gene flow• Genetic drift• Sexual Selection• Mutation• Speciation• Natural selection

Mechanisms for evolution

• Gene flow• Genetic drift• Sexual Selection• Mutation• Speciation• Natural selection

Gene flow is the movement of alleles between populations

• Gene flow increases genetic variation

What are alleles?

Mechanisms for evolution

• Gene flow

• Genetic drift (founder effect and bottleneck effect)

• Sexual Selection• Mutation• Speciation• Natural selection

Genetic Drift

The process of allele frequency change (evolution) in a population due to chance or random events

Genetic drift can be expressed as a “bottleneck effect”

• It is usually as a result of a catastrophe or unforeseen event

Genetic drift can also be caused by the “Founder Effect.”

• It occurs after a small number of individuals colonize a new area.

Mechanisms for evolution

• Gene flow• Genetic drift

• Sexual Selection• Mutation• Speciation• Natural selection

• Intrasexual - involves competition between males

Sexual selection occurs when certain traits increase mating success

Sexual selection• Intersexual - involves traits that attract the opposite sex

White board

A change in the allele frequency due to migration (individual coming in or out) in a population is called?

1. genetic drift2. sexual selection3. bottleneck effect4. gene flow

The five factors that can lead to evolution are gene flow, genetic drift, mutation, natural selection, and

1. sexual selection2. controlled mating3. emigration4. immigration

White board

________ changes allele frequencies due to chance alone

1. Natural selection2. Gene flow 3. Genetic drift4. Mutations

White board

Critical thinking

• How does gene flow affect neighboring populations?

Critical thinking

• How does gene flow affect neighboring populations?

• Gene flow decreases genetic diversity between neighboring populations.

Critical thinking

• Would a population of 10 individuals or 100 individuals be more vulnerable to genetic drift? Why?

Critical thinking

• Would a population of 10 individuals or 100 individuals be more vulnerable to genetic drift? Why?

• A smaller population is more vulnerable to genetic drift because it has a smaller gene pool and is therefore more likely to be affected by chance events.

IBE - JTPS

• Have you ever wondered why many male birds, such as cardinals, are brightly colored while females of the same species are dull brown? Such bright coloring may not make sense in terms of natural selection, since the male birds are more likely to be seen by predators. However, natural selection is not the whole story.