Department of Biological Sciences, National University of Singapore, Singapore.
Center for Ecological Sciences, Indian Institute of Science, Bangalore, Karnataka, India.
Genome Biol Evol. 2020 Apr 1;12(4):259-272. doi: 10.1093/gbe/evaa030.
Major novel physiological or phenotypic adaptations often require accompanying modifications at the genic level. Conversely, the detection of considerable contractions and/or expansions of gene families can be an indicator of fundamental but unrecognized physiological change. We sequenced a novel fruit bat genome (Cynopterus brachyotis) and adopted a comparative approach to reconstruct the evolution of fruit bats, mapping contractions and expansions of gene families along their evolutionary history. Despite a radical change in life history as compared with other bats (e.g., loss of echolocation, large size, and frugivory), fruit bats have undergone surprisingly limited change in their genic composition, perhaps apart from a potentially novel gene family expansion relating to telomere protection and longevity. In sharp contrast, within fruit bats, the new Cynopterus genome bears the signal of unusual gene loss and gene family contraction, despite its similar morphology and lifestyle to two other major fruit bat lineages. Most missing genes are regulatory, immune-related, and olfactory in nature, illustrating the diversity of genomic strategies employed by bats to contend with responses to viral infection and olfactory requirements. Our results underscore that significant fluctuations in gene family composition are not always associated with obvious examples of novel physiological and phenotypic adaptations but may often relate to less-obvious shifts in immune strategies.
主要的新生理或表型适应通常需要在基因水平上进行伴随的修改。相反，基因家族的大量收缩和/或扩张的检测可以是基本但未被认识到的生理变化的指标。我们对一种新型果蝠基因组（Cynopterus brachyotis）进行了测序，并采用了比较的方法来重建果蝠的进化史，绘制了基因家族在其进化过程中的收缩和扩张。尽管与其他蝙蝠相比（例如，失去回声定位、体型较大和食果性），果蝠的基因组成发生了惊人的有限变化，除了可能与端粒保护和长寿有关的潜在新型基因家族扩张之外。相比之下，在果蝠中，尽管新的 Cynopterus 基因组与另外两个主要的果蝠谱系具有相似的形态和生活方式，但它仍显示出异常的基因缺失和基因家族收缩的信号。大多数缺失的基因是调节、免疫相关和嗅觉相关的，说明了蝙蝠为应对病毒感染和嗅觉需求而采用的基因组策略的多样性。我们的研究结果强调，基因家族组成的显著波动并不总是与明显的新生理和表型适应相关，而可能经常与免疫策略的不明显变化有关。
