Escaping the evolutionary trap? Sex chromosome turnover in basilisks and related lizards (Corytophanidae: Squamata)
Escaping the evolutionary trap? Sex chromosome turnover in basilisks and related lizards (Corytophanidae: Squamata)
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DOI：
10.1098/rsbl.2019.0498
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发表时间：
2019-10-01
期刊：
影响因子：
3.3
通讯作者：
Rovatsos, Michail
中科院分区：
文献类型：
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作者：
Nielsen, Stuart V.;Guzman-Mendez, Iran Andira;Rovatsos, Michail
大多数侧齿蜥蜴家族（蜥蜴、鬣蜥和它们的亲戚），除了蛇蜥和雀头蜥蜴（蜥科），都有同源的XX/XY性染色体，与鸡的第15号染色体同步。本研究首次采用RADseq、RNAseq和qPCR等方法鉴定了嗜核细胞性染色体。我们发现，所有被检测的纤盲体物种都有部分退化的XX/XY性染色体，与鸡的第17号染色体共线。转录组学分析表明，与其他已被充分研究的XX/XY系统（包括绿蜥鱼）中的剂量平衡性染色体不同，栉水母（Basiliscus vittatus）中x连锁基因的表达在两性之间不平衡，这在雄性异种配子下相当罕见。核原性染色体可能是一个罕见的例子，从稳定的，分化的性染色体的更替。然而，由于胸骨齿动物家族之间的系统发育分辨率较差，我们不能拒绝另一种假设，即纤体性染色体从一个未知的祖先系统独立进化而来。
Most pleurodont lizard families (anoles, iguanas and their relatives), with the exception of the basilisks and casquehead lizards ( family Corytophanidae), share homologous XX/XY sex chromosomes, syntenic with chicken chromosome 15. Here, we used a suite of methods (i.e. RADseq, RNAseq and qPCR) to identify corytophanid sex chromosomes for the first time. We reveal that all examined corytophanid species have partially degenerated XX/XY sex chromosomes, syntenic with chicken chromosome 17. Transcriptomic analyses showed that the expression of X-linked genes in the corytophanid, Basiliscus vittatus, is not balanced between the sexes, which is rather exceptional under male heterogamety, and unlike the dosage-balanced sex chromosomes in other well-studied XX/XY systems, including the green anole, Anolis carolinensis. Corytophanid sex chromosomes may represent a rare example of a turnover away from stable, differentiated sex chromosomes. However, because of poor phylogenetic resolution among pleurodont families, we cannot reject the alternative hypothesis that corytophanid sex chromosomes evolved independently from an unknown ancestral system.