Transcript Evolution 2
Evolution 2 Dr. James . Whitfield, Ph.D Hardy-Weinberg Equilibrium Five Factors are known to effect HWE, these include Hardy-Weinberg Equilibrium Five Factors are known to effect HWE, these include Gene migration or gene flow Hardy-Weinberg Equilibrium Five Factors are known to effect HWE, these include Gene migration or gene flow Genetic drift Hardy-Weinberg Equilibrium Five Factors are known to effect HWE, these include Gene migration or gene flow Genetic drift Mutation Hardy-Weinberg Equilibrium Five Factors are known to effect HWE, these include Gene migration or gene flow Genetic drift Mutation Genetic recombination Hardy-Weinberg Equilibrium Five Factors are known to effect HWE, these include Gene migration or gene flow Genetic drift Mutation Genetic recombination Natural selection Founder Effect The founder effect can result if genes/alleles migrate from one population to another. Genes are lost in the original and added to the new population. If this migration happens multiple times it is called gene flow. If the same changes occur by chance it is called genetic drift. In any of these cases if the change is substantial enough speciation may occur and these individuals will become the founders of future generations Founder Effect The founder effect can also occur as a result of a genetic bottleneck. A bottleneck can occur after a natural disaster or a severe disease that wipes out a significant percentage of the population. The surviving population may not represent the same genetic make-up as the original population hence the survivors become the founders of the new population Founder Effect The founder effect can also result as a consequence of natural selection. Given enough time natural selection coupled with gene flow, variation due to recombination of genes, gene flow and genetic drift can all lead to speciation. Three different types of populations may occur, they are referred to as Stabilizing Stabilizing – in stabilizing selection the average is favored and the extremes are tightened (less favorable) genetic diversity is decreased Robin eggs and human baby weight, spider size Directional Directional – in directional selection both extremes are favored but at different times Bird beaks, peppered moth Disruptive Disruptive – In disruptive selection both extremes are favored at the same time. It is not good to be average. Two distinct populations form Sea sponges Rabbits