Genome of the Tasmanian tiger provides insights into the evolution and demography of an extinct marsupial carnivore
Genome of the Tasmanian tiger provides insights into the evolution and demography of an extinct marsupial carnivore
复制标题
DOI：
10.1038/s41559-017-0417-y
复制
发表时间：
2018-01-01
影响因子：
16.8
通讯作者：
Pask, Andrew J.
中科院分区：
文献类型：
--
作者：
Feigin, Charles Y.;Newton, Axel H.;Pask, Andrew J.
塔斯马尼亚虎或袋狼（Thylacinus cynocephalus）是最大的食肉澳大利亚有袋动物生存到现代。尽管最后一次与真兽目犬科动物共享共同的祖先类似于1.6亿年前，但它们的表型相似性被认为是哺乳动物趋同进化的最引人注目的例子。最后一只已知的袋狼于1936年在人工饲养中死亡，这种独特的有袋类顶端捕食者的进化历史的许多方面仍然未知。在这里，我们对保存的袋狼育儿袋幼标本的基因组进行了测序，以阐明袋狼在食肉有袋动物中的系统发育位置，重建其历史人口统计学，并研究其与犬科动物趋同的遗传基础。反转录插入模式放置的袋狼作为基础血统Dasyuromorphus，并建议不完整的血统排序早期dasyuromorphs。人口统计学分析表明，在人类到达澳大利亚之前，遗传多样性就开始长期下降。尽管他们非凡的表型趋同，比较基因组分析表明，袋狼和犬科动物之间的氨基酸同源性在很大程度上是一致的中性进化。此外，正选择所针对的基因和途径在这些物种之间存在显著差异。总之，这些发现支持主要由顺式调控进化驱动的适应性收敛模型。
The Tasmanian tiger or thylacine (Thylacinus cynocephalus) was the largest carnivorous Australian marsupial to survive into the modern era. Despite last sharing a common ancestor with the eutherian canids similar to 160 million years ago, their phenotypic resemblance is considered the most striking example of convergent evolution in mammals. The last known thylacine died in captivity in 1936 and many aspects of the evolutionary history of this unique marsupial apex predator remain unknown. Here we have sequenced the genome of a preserved thylacine pouch young specimen to clarify the phylogenetic position of the thylacine within the carnivorous marsupials, reconstruct its historical demography and examine the genetic basis of its convergence with canids. Retroposon insertion patterns placed the thylacine as the basal lineage in Dasyuromorphia and suggest incomplete lineage sorting in early dasyuromorphs. Demographic analysis indicated a long-term decline in genetic diversity starting well before the arrival of humans in Australia. In spite of their extraordinary phenotypic convergence, comparative genomic analyses demonstrated that amino acid homoplasies between the thylacine and canids are largely consistent with neutral evolution. Furthermore, the genes and pathways targeted by positive selection differ markedly between these species. Together, these findings support models of adaptive convergence driven primarily by cis-regulatory evolution.