Conservation of Genetic Diversity - Introduction to Conservation Biology - Lecture Slides, Slides of Biology

Download Conservation of Genetic Diversity - Introduction to Conservation Biology - Lecture Slides and more Slides Biology in PDF only on Docsity! Conservation of Genetic Diversity Docsity.com Some Mechanisms of Evolution Mutation Genetic accommodation – adaptive evolution Random processes (e.g., genetic drift) Gene flow via emigration & immigration Artificial selection Natural selection (Thank you, Darwin [& Wallace]!) – adaptive evolution Sexual selection (Thank you, Darwin!) – adaptive evolution Evolution – allele frequency change through time in a population Conservation of Genetic Diversity Docsity.com Inbreeding – results from mating by closely related individuals Genetic diversity erodes especially quickly in small, isolated populations Generation 1 Generation 2 Pop. A Pop. B 33% chance of mating with sibling 50% chance of mating with sibling Conservation of Genetic Diversity Docsity.com Genetic diversity erodes especially quickly in small, isolated populations Random processes (demographic bottlenecks, genetic drift, founder effects) Generation 1 Generation 2 Conservation of Genetic Diversity Docsity.com Photo from Wikipedia Not all phenotypic diversity results from genetic diversity Genetic diversity helps determine evolutionary potential An architect of the Modern Synthesis Fisher’s Fundamental Theorem: "The rate of increase in fitness [owing to selection] of any organism at any time is equal to its genetic variance in fitness at that time" R. A. Fisher (1890 – 1962) Conservation of Genetic Diversity Docsity.com Genetically effective population size (Ne) – the number of individuals that would result in the same level of inbreeding, or decrease in genetic diversity through time, if the population were an idealized, panmictic (randomly mating) population Typically  Ne < N (Because of variance in reproductive success and family sizes) Greater Yellowstone Ecosystem grizzlies: N ≈ 500 Ne ≈ 80 Conservation of Genetic Diversity Docsity.com Genetically effective population size (Ne) – the number of individuals that would result in the same level of inbreeding, or decrease in genetic diversity through time, if the population were an idealized, panmictic (randomly mating) population Typically  Ne < N (Because of variance in reproductive success and family sizes) Conservation of Genetic Diversity Generation 1: ♀ ♂ ♀ ♂ ♀ ♂ ♀ ♂ ♀ ♂ Generation 2: ♀ ♂ ♀ ♂ ♀ ♂ ♀ ♂ ♀ ♂ Docsity.com Small populations are at risk of extinction owing to the “one- two punch” from demographics and genetics Extinction Vortex Docsity.com Case Study: Eurasian wolf Vilà et al. (2003) Rescue of a severely bottlenecked wolf (Canis lupus) population by a single immigrant A single immigrant arrived onto the Scandinavian peninsula in 1991 1983 1991 2001 E st im at ed p op ul at io n si ze N um be r o f b re ed in g pa ck s 0 50 100 0 4 8 12 Docsity.com Case Study: Eurasian wolf Vilà et al. (2003) Rescue of a severely bottlenecked wolf (Canis lupus) population by a single immigrant A single immigrant arrived onto the Scandinavian peninsula in 1991 1983 1991 2001 In di vi du al h et er oz yg os ity (1 9 au to so m al m ic ro sa te llit e lo ci ) 1978 Each circle = 1 wolf 0 0.5 1.0 Founding female (est. date of birth = 1978) Pups with d.o.b. < 1991 (only 1 bottlenecked, inbred pack) Offspring of immigrant male Other pups with d.o.b. ≥ 1991 Docsity.com Case Study: North American wolf Adams et al. (2011) Genomic sweep and potential genetic rescue during limiting environmental conditions in an isolated wolf population “…a male wolf (Canis lupus)… immigrated [in 1997]… across Lake Superior ice to the small, inbred wolf population in Isle Royale National Park. The immigrant’s fitness so exceeded that of native wolves that within 2.5 generations he was related to every individual in the population… resulting in a selective sweep of the total genome.” Docsity.com