BIO111 Chapter 19 Population Evolution

BIO111 Chapter 19 Population Evolution

Population Evolution Summary

- Hardy-Weinberg Analysis

- Genetic Drift

- Bottleneck/Founders Effect

- Gene Pool/Gene Flow

- Environmental Impact on Genes

- Selection Types

- Frequency Dependent Selection

- Sexual Dimorphism

- Evolution Summary

Hardy-Weinberg Analysis

Chapter 19

Multiple Choice

If the Hardy-Weinberg data suggests the value for an allele is greater than normal, scientists can assume that:

• Evolutionary forces are at play

• Evolutionary forces are not at play

Gene Pool/Genetic Drift

Chapter 19

Gene Pool

• Remember, the gene pool is an inclusive list of all the alleles and their frequencies in a given population.

• Anything that happens to the gene pool in a population or populations can affect evolution of the population(s) in multiple ways

This is one way the gene pool is affected

Bottleneck Event/Founders Effect

Chapter 19

Founders effect from a bottleneck event. This also changes the gene pool

Gene Flow

Chapter 19

Multiple Choice

If genes are lost because a few individuals die or migrate at random and the gene pool changes, this is due to:

• genetic drift

• gene flow

• bottleneck

• founders effect

Multiple Choice

Gene flow tends to ______ differences among gene pools

• increase

• reduce

Multiple Choice

Either a catastrophic event or a migration to a new area that causes your gene pool to drastically be shrunk

• gene flow

• genetic drift

• bottleneck event

• founders effect

Environmental Impact on Genes and Evolution

Chapter 19

another example of environmental factors influencing gene pools, this time with human evolution.

Selection Types

Chapter 19

Multiple Choice

The type of selection where an average phenotype is favored

• stabilizing selection

• directional selection

• diversifying selection

Multiple Choice

The type of selection where two or more extreme phenotypes are selected for, while the average phenotype is selected against.

• stabilizing selection

• directional selection

• diversifying selection

Frequency Dependent Selection

Chapter 19

Positive FDS

In positive frequency-dependent selection, the fitness of a phenotype or genotype increases as it becomes more common.

Example: Müllerian mimicry is a natural phenomenon in which two or more well-defended species, often foul-tasting and that share common predators, have come to mimic each other's honest warning signals, to their mutual benefit.

Negative FDS

In negative frequency-dependent selection, the fitness of a phenotype or genotype decreases as it becomes more common. This is an example of stabilizing selection as well.

Example: A yellow-throated side-blotched lizard is smaller than either the blue-throated or orange-throated males and appears a bit like the females of the species, allowing it to sneak copulations. 

Sexual Dimorphism

Chapter 19

Multiple Choice

Sexual dimorphism leading to the sexes of organisms developing totally different features means that they had different ________ _______ at play and went down different evolutionary paths, whilst still being the same species.

• environmental surroundings

• evolutionary pressures

• negative experiences

• gene pools

Evolution Summary

Chapter 19

Multiple Choice

Evolution occurs to individuals

• true

• false

Multiple Choice

Natural selection can affect individuals

• true

• false

Multiple Choice

Evolution's goal is to make the best adapted organism

• true

• false

Summary/What to Study

- Hardy-Weinberg Analysis

- Genetic Drift

- Bottleneck/Founders Effect

- Gene Pool/Gene Flow

- Environmental Impact on Genes

- Selection Types

- Frequency Dependent Selection

- Sexual Dimorphism

- Evolution Summary