1 / 9

Understanding Evolutionary Processes: Key Concepts and Mechanisms

Explore the Hardy-Weinberg principle as a null hypothesis, the four evolutionary mechanisms, and the impacts of natural selection, genetic drift, gene flow, mutation, inbreeding, and sexual selection on genetic diversity and allele frequencies.

cain-henry
Download Presentation

Understanding Evolutionary Processes: Key Concepts and Mechanisms

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 25 Evolutionary Processes

  2. Key Concepts • The Hardy-Weinberg principle acts as a null hypothesis when researchers want to test whether evolution or nonrandom mating is occurring at a particular gene. • Each of the four evolutionary mechanisms has different consequences. Only natural selection produces adaptation. Genetic drift causes random fluctuations in allele frequencies. Gene flow equalizes allele frequencies between populations. Mutation introduces new alleles.

  3. Key Concepts, cont’d • Inbreeding changes genotype frequencies but does not change allele frequencies. • Sexual selection leads to the evolution of traits that help individuals attract mates. It is usually stronger on males than on females

  4. Hardy-Weinberg Principle • A mathematical model to analyze alleles in a population • p2 + 2pq + q2 = 1 • p + q = 1 • p symbolizes frequency of one allele (A1) and q symbolizes frequency of another allele (A2) • frequency x 100 = % • pp = homozygous for A1, qq = homozygous for A2, and pq is heterozygous

  5. Evolutionary Mechanisms • Natural Selection- alleles are favored, dependent on the environment • Genetic Drift- any change in allele frequencies in a population that is due to chance • Gene Flow- movement of alleles from one population to another • Mutation- changes in the makeup of chromosomes or in specific DNA sequences

  6. Natural Selection • Directional Selection- selection where the population goes to an allele away from the average • Stabilizing Selection- selection where more of the population express the average allele • Disruptive Selection- population where the population splits into two alleles different from the average

  7. Genetic Drift • Random elimination of a portion of the population (not dependent on traits) • Causes: • Bottleneck Effect- random death • Founder Effect- colonizing in another location

  8. Evolutionary Mechanisms • Gene Flow: migration of a members of the population to another population • Mutations: change in the DNA to produce new traits

  9. Inbreeding • Inbreeding- increases homozygous dominant and recessive genotypes • Sexual Selection- acquired traits by males increase rate of reproduction • Increase the frequency of the trait in a population

More Related