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《PNAS》在线发表武汉大学生态学系赵华斌教授研究组在动物进化与生态适应研究方向取得新研究进展文章,论文题目为:Sympatric speciation revealed by genome-wide divergence in the blind mole rat Spalax 。武汉大学生命科学学院硕博连读生洪炜同学为共同第一作者,硕士生焦恒武同学为第二作者,赵华斌为共同通讯作者,武汉大学为第一完成单位。

生物对环境的适应是进化生物学研究的基础问题,也是生态学研究的热点。然而,饱受争议的科学问题是:生活在同一区域内的哺乳动物能否快速适应不同的环境并分化出新的物种?针对这个问题,赵华斌与以色列海法大学的研究人员合作,对一种分布于同一区域的盲鼹鼠进行了全基因组重测序,揭示了该地下鼠的两个群体适应不同土壤环境的分子机制。群体基因组学研究表明,两个群体的分歧时间仅仅为20-40万年,自然选择已经驱动了300多个功能基因的强烈分化,而且两个群体的地下鼠受到自然选择的基因显著不同:一个群体中受选择的基因具有感觉、运动、能量代谢等功能,而另一个群体中受选择的基因具有营养代谢、神经调控等功能。进一步的群体遗传学研究表明,嗅觉和味觉受体基因在两个群体中也具有显著分化,提示配偶选择(嗅觉)和栖息地选择(味觉)促进了两个群体的强烈分化。研究还发现,两个动物群体具有显著不同的蛋白质降解机制。因此,即使没有地理隔离,哺乳动物也可以快速适应不同的环境并分化出新的物种,也就是同域成种。由于大自然能在同一区域内塑造出很多显著不同的小生境,类似的物种分化现象应该更普遍。

该研究组近期还在进化生物学期刊《Genome Biololgy and evolution》发表一篇论文,题目为BirdsGENErally carry a small repertoire of bitter taste receptor genes,武汉大学生命科学学院博士生汪凯同学为第一作者,其导师赵华斌为第二作者。鸟类是地球上物种多样性最丰富的四足类脊椎动物,其食性也非常多样。利用最新发表的48种鸟类基因组,汪凯同学通过基因组挖掘和分子进化分析发现,鸟类的苦味受体基因很少,提示鸟类的味觉功能退化。然而,该研究还发现,鸟类苦味受体基因的数目和其食物中有毒物质(通常为苦味)的含量具有显著的正相关关系,提示鸟类的苦觉仍然能分辨出食物中的有毒物质,食性偏好是鸟类味觉基因进化的主要推动力。因此,苦觉仍然是鸟类防止摄食有毒有害食物的重要防御机制。

原文链接:

Sympatric speciation revealed by genome-wide divergence in the blind mole rat Spalax

原文摘要:

Sympatric speciation (SS), i.e., speciation within a freely breeding population or in contiguous populations, was first proposed by Darwin [Darwin C (1859) On the Origins of Species by Means of Natural Selection] and is still controversial despite theoretical support [Gavrilets S (2004) Fitness Landscapes and the Origin of Species (MPB-41)] and mounting empirical evidence. Speciation of subterranean mammals generally, including the genus Spalax, was considered hitherto allopatric, whereby new species arise primarily through geographic isolation. Here we show in Spalax a case of genome-wide divergence analysis in mammals, demonstrating that SS in continuous populations, with gene flow, encompasses multiple widespread genomic adaptive complexes, associated with the sharply divergent ecologies. The two abutting soil populations of S. galili in northern Israel habituate the ancestral Senonian chalk population and abutting derivative Plio-Pleistocene basalt population. Population divergence originated ∼0.2–0.4 Mya based on both nuclear and mitochondrial genome analyses. Population structure analysis displayed two distinctly divergent clusters of chalk and basalt populations. Natural selection has acted on 300+ genes across the genome, diverging Spalax chalk and basalt soil populations. Gene ontology enrichment analysis highlights strong but differential soil population adaptive complexes: in basalt, sensory perception, musculature, metabolism, and energetics, and in chalk, nutrition and neurogenetics are outstanding. Population differentiation of chemoreceptor genes suggests intersoil population's mate and habitat choice substantiating SS. Importantly, distinctions in protein degradation may also contribute to SS. Natural selection and natural genetic engineering [Shapiro JA (2011) Evolution: A View From the 21st Century] overrule gene flow, evolving divergent ecological adaptive complexes. Sharp ecological divergences abound in nature; therefore, SS appears to be an important mode of speciation as first envisaged by Darwin [Darwin C (1859) On the Origins of Species by Means of Natural Selection].


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