3.3 Study Guide

Mechanisms of Evolution

Events and occurrences that cause or lead to evolution

Natural Selection

Traits become more or less common in a population

Mutation

Any permanent alteration of the nucleotide sequence of the genome of an organism

Genetic Variability

Differences between organisms and genomes that are members of the same species and allows species to be able to adapt to change in their environment.

Gene Flow/Allelic Flow

Migration of an individual into a new population can cause major changes in the allelic frequencies of that population over time.

Immigration

Moving to a new country and staying there.

Emigration

Leaving a country to settle somewhere else.

Sexual Selection

Event that can affect gene flow, and is also a mechanism of evolution.

Intersexual Selection

When one gender chooses which other individuals to mate with.

Intrasexual Selection

When members of one gender compete between eachother for the ‘right’ to reproduce.

Genetic Drift

Change in the frequency of a gene/allele in a populations due to random sampling of the organisms of that species.

Population Bottleneck

Types of organisms links cheetahs, pandas, or elephants. They experienced a sharp decline in population over a 100 or so period, which was usually the result of human involvement.

Founder Effect

When a small group splits off into a larger group to start a new colony, the genomes of the founders of the group, even for many generations to come. Founder of a new population effects the gene/allele frequencies in that group.

Speciation

the evolutionary process by which populations evolve to become distinct species

Hardy-Weinberg Outcomes

1) Genotypic ratios cannot change in a single generation

2) Frequency of the 2 alleles will remain the same from generation to generation, unless other stuff gets in the way like mutation