Genetic diversity 4 Conservation genetics

Proses Evolusi 1) Natural Selection (seleksi alam) 2) Gene Flow 3) Genetic Drift

Evolutionary Processes— 1) Natural Selection A major mechanism of evolution as proposed by Darwin A filter for genetic variation: the best adapted individuals survive and reproduce in greater numbers over time Not a directed process! Changes in direction and intensity depend on conditions and time span

Evolutionary Processes— 2) Gene Flow The exchange of genetic material within a population, between populations of a species, and even between species Gene flow among populations of a species maintains the integrity of the species Lack of gene flow can lead to speciation

Evolutionary Processes— 2) Gene Flow sympatric speciation = reproductive isolation of parent species from hybrid derivatives through hybridization and chromosome doubling without geographic isolation

Evolutionary Processes— 3) Genetic Drift Changes in the gene pool of a small population due to chance events Founder effect = one or two individuals disperse and start a new population with limited genetic diversity Bottleneck = extreme reduction in population size and therefore genetic diversity

Conservation Genetics Involves the use of genetic data and principles to guide conservation activities Genetics should be prominent in the practice of conservation

Conservation Genetics 1) Rate of evolutionary change in a population is proportional to the amount of genetic diversity available 2) Higher genetic diversity is usually positively related to fitness 3) Global pool of genetic diversity represents all of the information for all biological processes (= genetic library)

Conservation Genetics Small populations tend to lose genetic diversity over time!!!

Conservation Genetics Habitat fragmentation and destruction now produce and will continue to produce small, isolated populations Understanding the genetic status of species and populations and the consequences of small population sizes is vital to conservation, management, and recovery efforts.

Conservation Genetics A major goal is to preserve natural patterns of genetic diversity to the extent possible to preserve options for future evolutionary change.

Conservation Genetics— Example: Prairie Chickens 35-year study of a remnant population of prairie chickens in Illinois In 1962, about 2,000 individuals present; in 1994, fewer than 50 Fertility and hatching rates declined significantly, as did genetic diversity Translocation program established in 1992 to bring in birds from MN, KS and NE

Conservation Genetics— Example: Prairie Chicken By 1994, increased survival of young prairie chickens was verified By 1997, there were significant increases in mean rates of fertility and hatching Once the main population in Illinois became isolated, it began to lose viability and without intervention, it most likely would have disappeared