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，基因组的大片区域经历基因沉默和丢失。这种基因组退化令人惊讶，因为它与自然选择应该继续推动基因改善功能的普遍预测背道而驰。尽管如此，大规模的基因退化还是反复发生，包括非重组性染色体上的基因反复退化，以及全基因组复制后重复基因的丢失。推动退化进化的进化力量尚不清楚；一种可能性是，它可能是由通过自然选择效率降低而导致的基因失活和丧失的“被动”过程驱动的。虽然减少选择可能很重要，但适应过程也可能起到作用：衍生基因拷贝之间的适合度差异可能会导致适应性基因失活和丢失，从而加速退化。

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.