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This month we find out if inbreeding spells doom for endangered populations, whether bottlenecks can lead to degeneration of genes, how X chromosome influences sperm length and much more.
You say Inbred, we say adapted.
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Researchers find nearly extinct species of Goodeid fish is inbred in the wild.
The significance of genetic and non-genetic factors in driving extinction has been debated at length. In a paper published as Advanced Online Publication on 28 February 2007, Prof. Michael Ritchie and colleagues compared the genetic diversity, using microsattelite loci, of wild populations of two nearly extinct species of Goodeid fish (Z.tequila and A.splendens) with samples from captive stocks. They found that genetic diversity indices, such as alleic richness, were significantly higher in the wild than in captive populations for both species. Both species also showed evidence of exponential population decline, but the evidence in Z.tequila was stronger. However, the wild Z.tequila population, the only known extant population, showed indications that its genetic variability had declined from its probable ancestral levels.
The authors considered the implications of their findings for the conservation of critically endangered populations. They proposed that “the viability of wild stocks should not be compromised by attempts to increase their genetic diversity in the absence of evidence of inbreeding depression. [Such attempts] may promote the spread of deleterious alleles adapted to captivity.” In the case of Z.tequila, the wild population has survived at least 15 years of such severe isolation that it has probably undergone an amount of local adaptation. Any rescue attempts that introduce captive stocks could mean a sad trade-off said Ritchie and colleagues. “[We] risk breaking down a locally adapted genome (and one purged of deleterious alleles) by introducing alleles adapted to captivity, or risk local extinction due to [unpredictable] environmental changes to which this genetically impoverished population cannot adapt.
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