Genetic Diversity in Endangered Species PDF

Genetic Diversity in Endangered Species Ayesha Aslam MPhil Biotechnology  Genetic Diversity Genetic diversity refers to the total number of genetic characteristics in the genetic makeup of a population A crucial component of Biodi...

Genetic Diversity in Endangered Species Ayesha Aslam MPhil Biotechnology  Genetic Diversity Genetic diversity refers to the total number of genetic characteristics in the genetic makeup of a population A crucial component of Biodiversity Adaptability and survival of species, particularly in changing environments Genetic Diversity  Levels of Genetic Diversity Intraspecific – Population Interspecific – Community  Key Terms in Genetic Diversity Individual vs Population Allelic Richness  Causes of Genetic Diversity Mutations Genes 1. Point Mutations (Sense, Non-sense, Missense) 2. In-dels – Frameshift Chromosomes  Causes of Genetic Diversity Gene Flow Migration Sexual Reproduction Meiosis  Causes of Genetic Diversity Natural Selection Positive Negative Neutral Life History Traits and Genetic Diversity  Extent of Genetic Diversity Large populations of outbreeding species contain vast amounts of genetic diversity. This is manifested in morphological, behavioural and physiological variations in most populations. An example of the large amount of genetic diversity inherent in a species is the variety of dog breeds that have been produced from the wolf genome, reflecting the extent of genetic diversity that was present in the ancestral wolves.  Reduction in Genetic Diversity Human Activities Habitat Destruction Overexploitation Pollution Global Warming  Reduction in Genetic Diversity Habitat Fragmentation Dividing a large habitat into smaller, isolated areas  Reduction in Genetic Diversity Population Bottlenecks An event that drastically reduces the size of a population Population is reduced to a very small subset of the original larger population  Reduction in Genetic Diversity Inbreeding Inbreeding is the mating together of individuals which are related to each other through having one or more ancestors in common. Increase in genomic homozygosity  Reduction in Genetic Diversity Genetic Drift Genetic drift is the random fluctuation of allele frequencies in a population due to chance events. Genetic drift can lead to the random loss of alleles from a population, particularly rare alleles.  Consequences Inbreeding Depression Reduction in the biological fitness of offspring that can result from inbreeding Increased genome-wide homozygosity  Consequences Evolutionary Potential The property of a biological entity to be able to experience heritable change in some of its components over time. Reduction in Evolutionary Potential  Consequences Extinction Vortex The extinction vortex is a self-reinforcing process in which small populations are increasingly likely to decline toward extinction due to a combination of genetic, demographic, and environmental factors.  Threatened Species A threatened species is any species (including animals, plants and fungi) which is vulnerable to extinction in the near future. Include vulnerable, endangered, and critically endangered species. Threatened Species Endangered Species  Case Study 1 Cheetah (Acinonyx jubatus) Cheetahs have one of the lowest levels of genetic diversity among mammals. Population bottleneck that occurred around 10,000 years ago Susceptible to diseases Cheetahs also suffer from poor sperm quality, low sperm count, and high cub mortality  Case Study 2 Florida Panther (Puma concolor coryi) By the 1990s, the population had dwindled to about 20-30 individuals due to habitat loss, hunting, and other human activities. This small population size led to severe inbreeding, leading to inbreeding depression Less environmental adaptability and increased disease susceptibility  Case Study 3 Tasmanian Devil (Sarcophilus harrisii) Bottleneck Population Significant threat from Devil Facial Tumor Disease (DFTD) Led to an estimated 80% decline in the wild population over the last few decades  Case Study 4 Amur Leopard (Panthera pardus orientalis) Native to Russian Far East and northeastern China Poaching, habitat loss and degradation, prey depletion, and anthropogenic threats By the early 21st century, fewer than 30 individuals were estimated to remain in the wild Inbreeding  Case Study 5 Black rhinoceros (Diceros bicornis) Endangered because of demand for rhino horns on the Asian illegal international market, where rhino horn is used for traditional medicine, and increasingly as a status symbol to display success and wealth Genetic Bottleneck – Inbreeding depression – Habitat fragmentation  Case Study 6 Mahogany Tree Timber – building and carpentry Overexploitation Habitat loss due to agricultural expansion, urban development, and deforestation  Recommended Reading Ellegren H, Galtier N. (2016) Determinants of genetic diversity. Nature Reviews Genetics. Charlesworth D, Willis J.H. (2009). The genetics of inbreeding depression. Nature Reviews Genetics. Richard Frankham (2004). A Primer of Conservation Genetics. Cambridge University Press.