Mechanisms of Evolution Lesson PDF

MECHANISMS The Processes of Evolution 1 LEARNING GOALS Ican identify factors that can change the allele frequencies in populations. Ican describe, with the use of examples, gene flow, mutations, non-random mating, and genetic drift. 2...

MECHANISMS The Processes of Evolution 1 LEARNING GOALS Ican identify factors that can change the allele frequencies in populations. Ican describe, with the use of examples, gene flow, mutations, non-random mating, and genetic drift. 2 1  Evolution MICROEVOLUTION VS. MACROEVOLUTION 3 Macroevolution  Theorigin of taxonomic groups higher than the species level. 4 2  Microevolution A change in a population’s gene pool over a succession of generations.  Evolutionary changes in species over relatively brief periods of geological time. 5 WHERE DOES VARIATION COME FROM? 6 3  Mechanisms of Microevolution 1. Genetic drift 2. Gene Flow/ Migration 3. Mutation 4. Non-Random Mating/ Sexual Selection 7 1. GENETIC DRIFT 8 4  1. Genetic drift: Change in the gene pool of a small population due to chance.  Twoexamples: a. Bottleneck effect b. Founder effect 9 a. Bottleneck Effect  reduction of alleles in a population  result from a disaster that drastically reduces population size.  Examples: 1. Earthquakes 2. Volcano eruption 10 5 11 b. Founder Effect  resultingfrom the colonization of a new location by a small number of individuals.  Results in random change of the gene pool.  Example: 1. Islands (first Darwin finch) 2. Polydactyl 12 6  2. GENE FLOW 13 The gain or loss of alleles from a population by the movement of individuals or gametes. Immigration or emigration Ex: Prairie dog colonies 14 7 15 3. MUTATION 16 8  Mutation: Change in an organism’s DNA that creates a new allele. Inheritable mutations can be: neutral, harmful, or beneficial 17 4. NON-RANDOM MATING 18 9  4. Non-random mating: The selection of mates other than by chance. 19 Non-Random Mating  Animalschose their mates based on their phenotypes  Ex. Peacocks Sage grouse Caribou 20 10  Intrasexual competition – male vs. male competition for mates and to establish and defend territory 21 Non-Random Mating  Inbreeding may occur when closely related individuals breed together  As homozygous genotypes become more common, harmful recessive alleles will be expressed 22 11  ASSIGNMENT  Supplementary Reading p.350- 357  Answer Pg. 359 #2, 3, 5- 11  Watch Video Clips: https://www.youtube.com/watch?v=nPhVO ZiPokA https://www.youtube.com/watch?v=gsMx- nT1aPM https://www.youtube.com/watch?v=YTR21os 8gTA&feature=emb_logo 23 12