Populations only lose genetic diversity - Slower or faster - Genetic entropy is a biological fact
https://www.sciencedirect.com/science/article/pii/S000632071530032XA few real life examples of genetic entropy:
Monitoring age-related trends in genomic diversity of Australian lungfish
"They then compared empirical estimates of heterozygosity and allelic richness between threatened and non-threatened species, and found that genetic diversity is generally reduced in threatened species. However, when they considered which of the IUCN Red List Criteria (including declining population size, species range extent, and the number of mature individuals) are most effective at identifying genetically depauperate species, they found that the existing criteria failed to systematically identify populations with low genetic diversity ( Willoughby et al., 2015). Thus, threatened species generally show reduced genetic diversity compared to non-threatened ones (Spielman et al., 2004), but the IUCN Red List Criteria approach does not systematically prioritize the conservation of species with low genetic diversity ( Rivers et al., 2014;Willoughby et al., 2015). ..."
"... However, when they considered which of the IUCN Red List Criteria (including declining population size, species range extent, and the number of mature individuals) are most effective at identifying genetically depauperate species, they found that the existing criteria failed to systematically identify populations with low genetic diversity ( Willoughby et al., 2015). Thus, threatened species generally show reduced genetic diversity compared to non-threatened ones (Spielman et al., 2004), but the IUCN Red List Criteria approach does not systematically prioritize the conservation of species with low genetic diversity ( Rivers et al., 2014;Willoughby et al., 2015). Additionally, the genetic consequences of habitat degradation and fragmentation in relation to the IUCN Red List Categories remain largely unexplored. ..."
Landscape Genomic Conservation Assessment of a Narrow-Endemic and a Widespread Morning Glory From Amazonian Savannas
... Such loss of evolutionary potential may increase the risk of extinction of local populations and degrade the persistence of the metapopulation (group of spatially structured local populations that may exchange individuals through migration, Frankham, 2005;Hanski, 1998). Hence, maintaining adequate levels of genetic diversity, within and among wildlife populations, is one of the main principles underlying the conservation T and management of threatened species ( Willoughby et al., 2015). ...
Low genetic diversity, limited gene flow and widespread genetic bottleneck effects in a threatened dolphin species, the Australian humpback dolphin
... The low variation that exists between the solenodon sequences is hardly surprising, because the theoretical consensus in conservation genetics predicts that small populations lose genetic diversity more rapidly than large populations [102], and measures of genetic diversity have been explicitly suggested to IUCN as a factor to consider in identifying species of conservation concern [103]. The historical N e for each subspecies was examined by our analysis (Figure 9), and showed lower levels recently in S. p. woodi.
Next-generation metrics for monitoring genetic erosion within populations of conservation concern
... Describing the patterns of distribution of genetic diversity can help define population units important for effective management and conservation[10]. Moreover, population genetic parameters can be used in a holistic framework to support recommendations regarding official international conservation rankings[11]. To date, while some primate groups have been more explored regarding their genetic structure, others remain poorly studied[12]. ...
... Based on the estimates of the effective population size obtained for the two biggest populations (Ne = 26 and 40), applying the equation for heterozygosity loss (Eqn. 4 in[11]), we can anticipate that the studied BGHM populations will lose heterozygosity below the 25% quantile of the current values in less than 50 generations. We also found that the populations at the southernmost limit of the species range have a reduced effective size and may be genetically depleted to face threatening events such as yellow fever outbreaks, which could rapidly affect all individuals in most of the species' distribution area. ...
Genetic structure in the southernmost populations of black-and-gold howler monkeys (Alouatta caraya) and its conservation implications
... This is especially true for threatened species, which can sometimes be characterised by low levels of genetic variation, often due to inbreeding, population bottlenecks, or the disproportionate effects of genetic drift on small populations (e.g. England et al. 2003;Spielman et al. 2004;Allendorf 2005;Willoughby et al. 2015). ...My comment: Rapid and efficient ecological adaptation is based on epigenetic regulation of existing biological information. Switching and regulating between alternative epigenetic programs never lead to any kind of evolution, because it doesn't cause growth of biological information. Instead, shifting methylation patterns typically result in subtle errors in DNA sequences. That's why genetic entropy is a biological fact. There's a deletional bias within all kind of organisms. We can only observe loss of genetic diversity within every type of populations, smaller or larger. There is no mechanism for evolution. The only alternative is Creation and Intelligent Design. Of course it's a good question why organisms are only experiencing genetic degradation. To get the answer, we have to open the Bible. Don't be deceived.
Genetic diversity and differentiation of the Western Leopard Toad (Sclerophrys pantherina) based on mitochondrial and microsatellite markers
... Genetic diversity is reduced in threatened taxa, relative to non-threatened taxa reflecting population bottlenecks and small population sizes [58][59][60][61]. We used data from the same section in the mitochondrial control region from a related and co-distributed finches to provide context for the measures of genetic diversity. ...
Three Molecular Markers Show No Evidence of Population Genetic Structure in the Gouldian Finch (Erythrura gouldiae)
... likely go to fixation when either N e or s are very large. In most endangered wildlife the former requirement is not met [30], thus selection will be of lesser importance than genetic drift for shaping genetic diversity in the population. Tasmanian devil populations with and without DFTD all had similar genetic diversity—a pattern that remained unaffected over time in DFTD populations (S1 File). ...
