Ezaz Tariq, Srikulnath Kornsorn, Graves Jennifer A Marshall
From the Institute for Applied Ecology, University of Canberra, Canberra, ACT 2617, Australia (Ezaz, Graves); Laboratory of Animal Cytogenetics and Comparative Genomics, Department of Genetics, Faculty of Science, Kasetsart University, 50 Ngam Wong Wan, Lat Yao, Chatuchak, Bangkok 10900, Thailand (Srikulnath); and School of Life Science, La Trobe University, Melbourne, Victoria 3086, Australia (Graves).
J Hered. 2017 Jan;108(1):94-105. doi: 10.1093/jhered/esw053. Epub 2016 Sep 15.
The diversity of sex chromosomes among amniotes is the product of independent evolution of different systems in different lineages, defined by novel sex-determining genes. Convergent evolution is very common, suggesting that some genes are particularly adept at taking on a sex-determining role. Comparative gene mapping, and more recently whole genome sequencing, have now turned up other surprising relationships; different regions of the amniote genome that have become sex determining in some taxa seem to share synteny, or share sequence, in others. Is this, after all, evidence that these regions were once linked in a super-sex chromosome that underwent multiple fission in different ways in different amniote lineages? Or does it signify that special properties of sex chromosomes (paucity of active genes, low recombination, epigenetic regulation to achieve dosage compensation) predispose particular chromosomes to a sex-determining role?
羊膜动物中性染色体的多样性是不同谱系中不同系统独立进化的产物，由新的性别决定基因所定义。趋同进化非常普遍，这表明一些基因特别擅长承担性别决定的角色。比较基因图谱，以及最近的全基因组测序，现已发现了其他令人惊讶的关系；在某些分类群中已成为性别决定区域的羊膜动物基因组的不同区域，在其他分类群中似乎具有同线性，或共享序列。这究竟是否证明这些区域曾经连接在一条超级性染色体上，而该超级性染色体在不同的羊膜动物谱系中以不同方式经历了多次裂变？或者这是否意味着性染色体的特殊特性（活性基因稀少、重组率低、通过表观遗传调控实现剂量补偿）使特定染色体倾向于承担性别决定的角色？
