Genetic diversity4

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