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Genetic Diversity in Natural Resources Management
Published in Yeqiao Wang, Landscape and Land Capacity, 2020
Thomas Joseph McGreevy, Jeffrey A. Markert
The demographic history of a population can impact its population dynamics and adaptive potential. When the size of a population is severely reduced, it is said to have undergone a bottleneck.[1] Similarly, founding events involve the establishment of a new population from a small number of individuals. Both bottlenecks and founding events result in populations with low genetic diversity and can impact their evolutionary trajectory because genetic information is lost randomly.[9] Lost genetic diversity in a population also can lead to inbreeding depression, which occurs when related or genetically similar animals mate and produce offspring. Inbreeding depression can manifest as reduced fitness of quantitative traits such as number of offspring produced or offspring survival rate.[10] All these forces can result in reduced adaptive potential and increased risk of extinction.[1]
Biodiversity: Tropical Agroforestry
Published in Yeqiao Wang, Terrestrial Ecosystems and Biodiversity, 2020
Genetic diversity is now being considered more frequently as a critical element of biodiversity.[17] This includes various measures of the variety of genetic material within a species or a population. Low genetic diversity can lead to short-, medium-, and long-term problems, such as inbreeding depression that shifts mean phenotypes in a direction that causes a reduction in fitness. Functional diversity, another important component, includes the biological and chemical processes such as energy flow and matter recycling needed for the survival of species, communities, and ecosystems.[18] Functional diversity also comprises the many ecological interactions among species (e.g., competition, predation, parasitism, mutualism, etc.), as well as the natural disturbances (e.g., fire, rain events, etc.) that many species and communities require. Ecological diversity considers the variety of terrestrial and aquatic ecosystems that are found in an area of the Earth.[18] Together, these four components comprise biodiversity.
Thirty years of conservation genetics in New Zealand: what have we learnt?
Published in Journal of the Royal Society of New Zealand, 2019
Inbreeding does not directly cause loss of allelic variation or change in allele frequency; rather, these are caused by the increased sampling error with reduced Ne. Inbreeding brings together genes that are identical by descent, which in turn tends to purge recessive deleterious alleles. In theory, if inbreeding depression were caused only by recessive deleterious alleles (dominance model; Charlesworth and Charlesworth 1987), then it should be possible to purge this genetic load from a population and further inbreeding would cease to show ill effects. Purging may have happened in successful selfers, but there is little evidence for it in threatened species (Grueber et al. 2010). Black robins are one of the most inbred animals in the world, yet show no evidence of purging and retain strong inbreeding depression (Kennedy et al. 2014). Claims have been made that NZ species might be adapted to inbreeding through their long history on islands. There is little or no evidence for this idea. Historic collections typically show high H compared with remaining remnant populations (Taylor et al. 2007). Besides, the deme size for terrestrial species is likely to be far smaller than the area of land covered by North or South Island; promotion of the idea was a counter-productive distraction (Jamieson et al. 2006).