Ch 23 - The Evolution of Populations (1 slide per page)-1

frequency of favorable traits will increase as will

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ce resources. • Those w/ favorable, heritable traits are more likely to survive and reproduce thus... • Frequency of favorable traits will increase (as will their alleles); frequency of unfavorable traits will decrease (as will their allels). 22 22 How Does Natural Selection Cause Allele Frequencies to Change? Alleles representing favorable traits survive and become more common in the population (↑ frequency) Alleles representing unfavorable traits become less common (↓ frequency) or are removed (↓ variation) 23 23 Genetic Drift When chance events cause unpredictable changes in allele frequencies from one generation to the next i.e. by chance either + or – alleles may increase in the next generation vs. Natural selection in which changes are predictable since specific (+) phenotypes and their associated alleles are favored 24 24 What type of chance events cause Genetic Drift? e.g. Chance survival of individuals causes random fluctuations in allele frequencies Allele that causes the brown phenotype increased in frequency due to luck not because it is better. GD could randomly result in the complete loss of an allele GD is most influential on small populations Unlike NS which always ↑ good alleles and ↓ bad ones, GD can ↑ either good or harmful alleles (and ↓ either too) 28 28 A Popu...
View Full Document

This note was uploaded on 02/12/2014 for the course BIOLOGY 2011 taught by Professor Woo during the Fall '10 term at University of Central Florida.

Ask a homework question - tutors are online