Population genomics of degenerative genome evolution

基因组进化最显著的特征之一是在退化进化的情况下发现的，其中基因组的大区域经历基因沉默和丢失。这样的基因组退化是令人惊讶的，因为它与自然选择应该不断推动基因改善功能的一般预测背道而驰。尽管如此，大规模的基因退化已经反复发生，包括非重组性染色体上基因的复发性退化，以及全基因组复制后重复基因的丢失。退化性进化的驱动力仍然不清楚;一种可能性是，它可能是由一个“被动”的基因失活和损失的过程，通过减少自然选择的功效。虽然减少选择可能很重要，但适应过程也可能有所贡献：衍生基因拷贝之间的适应性差异可能导致适应性基因失活和丢失，加速退化。

One of the most striking features of genome evolution is found in cases of degenerative evolution, whereby large regions of the genome experience gene silencing and loss. Such genome degeneration is surprising, as it runs counter to the general prediction that natural selection should continually be driving genes towards improved function. Despite this, large-scale gene degeneration has occurred repeatedly, including recurrent degeneration of genes on non-recombining sex chromosomes, and loss of duplicate genes following whole genome duplication. The evolutionary forces driving degenerative evolution remain unclear; one possibility is that it may be driven by a 'passive' process of gene inactivation and loss through a reduction in the efficacy of natural selection. While reduced selection is likely important, the process of adaptation may also contribute: differences in fitness between derived gene copies may lead to adaptive gene inactivation and loss, accelerating degeneration.