* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Forces of Evolutionary Change
Group selection wikipedia , lookup
Quantitative trait locus wikipedia , lookup
Medical genetics wikipedia , lookup
Genome evolution wikipedia , lookup
Point mutation wikipedia , lookup
Pharmacogenomics wikipedia , lookup
Behavioural genetics wikipedia , lookup
Site-specific recombinase technology wikipedia , lookup
Gene expression programming wikipedia , lookup
Dual inheritance theory wikipedia , lookup
Heritability of IQ wikipedia , lookup
Genetic testing wikipedia , lookup
Dominance (genetics) wikipedia , lookup
Public health genomics wikipedia , lookup
Hardy–Weinberg principle wikipedia , lookup
Designer baby wikipedia , lookup
Polymorphism (biology) wikipedia , lookup
History of genetic engineering wikipedia , lookup
Genetic engineering wikipedia , lookup
Genome (book) wikipedia , lookup
Human genetic variation wikipedia , lookup
Genetic drift wikipedia , lookup
Koinophilia wikipedia , lookup
Forces of Evolutionary Change Forces of Evolutionary Change • All of the factors that influence evolution and lead to new species relate to one of 4 main forces of evolution/change. • Those forces of change are: – Genetic Mutations – Gene flow (Genetic Migration) – Genetic Drift – Natural Selection Forces of Evolutionary Change • So…HOW do these forces actually lead to evolution?? • The four forces lead to changes in allele frequencies in a population • This leads to changes in the genetic variation of the population Forces of Evolutionary Change What are allele frequencies?? 1. A frequency is how often something occurs 2. Written as a percent (e.g. 50%) or proportion (e.g. 0.5) 3. Allele frequencies show how genetically diverse a population is. More alleles More diverse! More even percentages of those alleles More diverse! Genetic Mutations 1. Random process 2. Change in the genetic code (DNA) 3. These mutations are passed from parent to offspring 4. Mutations can be detrimental (bad) or advantageous (good) Gene Flow / Genetic Migration 1. Genes can move into or out of a population 2. As organisms move, they bring their genes with them 3. This leads to new allele combinations in the population Gene Flow / Genetic Migration Gene Flow / Genetic Migration Applies to plants, too! Pollen + seed movement… Effects of Gene Flow on Evolution Gene flow impacts evolution in multiple ways: 1. Introduces alleles into a population 2. Increases genetic variation Effects of Gene Flow on Evolution Gene flow impacts evolution in multiple ways: 1. Introduces alleles into a population 2. Increases genetic variation 3. MORE gene flow = Reduces the chance of new species forming 4. LESS gene flow = Increases the chance of new species forming Genetic Drift 1. Random change in allele frequencies 2. Due to “chance” 3. Has the greatest impact on small populations Genetic Drift Original allele frequencies in a population **Random Event** Changed allele frequencies due to random event Genetic Drift Founder Effect: a few individuals start a new population with different allele frequencies Natural Selection 1. Survival of the fittest 2. NOT random! Natural Selection 1. Survival of the fittest 2. NOT random! 3. Individuals with beneficial adaptations are more likely to survive and reproduce. 4. Results in a change in allele frequencies over time: – Beneficial alleles INCREASE – Detrimental alleles DECREASE Adaptive Traits Adaptation: Trait or behavior that helps an organism survive and reproduce in its environment Result of Natural Selection Natural selection results in a change in alleles frequencies! Sexual Selection • Type of natural selection One sex prefers certain characteristics in the other sex Let’s put it all together… • Which forces of evolutionary change INCREASE genetic diversity in a population? • Which forces of evolutionary change DECREASE genetic diversity in a population? Let’s put it all together… • Which forces of evolutionary change INCREASE genetic diversity in a population? Mutations and Gene Flow • Which forces of evolutionary change DECREASE genetic diversity in a population? Genetic Drift and Natural Selection What happens when allele frequencies change so much over time that the population looks and behaves really different?? Speciation • A species is a group of organisms that breed and reproduce fertile offspring • Speciation is the formation of a new species Speciation • Causes of speciation – Reproductive isolation – Behavioral isolation – Geographic isolation