中科院西高所博士后学者赵凯与合作导师赵新全研究员最近的一项研究结果表明同域的物种形成模式在青藏高原特有的高度特化裂腹鱼类物种之间很可能已经发生。基于线粒体标记的系统地理学分析显示，青藏高原一个冰川湖泊特有的斜口裸鲤（Gymnocypris ecklonie scoliostomu）完全具备了物种在同域条件下起源的标准。研究推断斜口裸鲤很可能起源自同域分布在逊木措湖的花斑裸鲤（G. e. eckloni）种群，主要的分歧时间发生在大约 0.057 百万年。
系统发育和种群遗传分析显示，在花斑裸鲤物种的所有地理种群之间，逊木措湖的花斑裸鲤种群与同域分布的斜口裸鲤个体保持最近的亲缘关系，暗示它们拥有一个最近的共同祖先，这一结果为检验正在发生的同域物种形成机制提供了理想的模式。斜口裸鲤表现出比花斑裸鲤更低的遗传多样性，而且更加新近的扩张时间被检测在新起源的斜口裸鲤种群中。我们认为斜口裸鲤很可能起源自目前同域分布在逊木措湖的花斑裸鲤种群，而不是通常假设的这个类群曾经有一个广泛的地理分布，后来在其它地区被灭绝。由于各自生态的特有性，斜口裸鲤和逊木措湖花斑裸鲤通过自然选择促进了同域条件下的种群分歧。该研究为进化生物学长期争论的同域物种形成理论提供了新的分子生态学证据，论文已发表在国际著名生态学期刊《分子生态学》（Molecular Ecology）上。（生物谷Bioon.com）
生物谷推荐原始出处：
Molecular Ecology Volume 18 Issue 17, Pages 3616 - 3628
The youngest split in sympatric schizothoracine fish (Cyprinidae) is shaped by ecological adaptations in a Tibetan Plateau glacier lake
KAI ZHAO*, ZI YUAN DUAN??, ZUO GANG PENG?§, SONG CHANG GUO*, JUN BING LI?, SHUN PING HE? and XIN QUAN ZHAO*
*Key Laboratory of Adaptation and Evolution of Plateau Biota (AEPB), Northwest Plateau Institute of Biology, Chinese Academy of Sciences, 810001 Xining, Qinghai, China , ?Laboratory of Fish Phylogenetics and Biogeography, Institute of Hydrobiology, Chinese Academy of Sciences, 430072 Wuhan, Hubei, China , ?Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, 100101 Beijing, China
Although new empirical evidence shows that sympatric speciation has occurred in some species, there are few indisputable model organisms for this process of speciation. The two subspecies (Gymnocypris eckloni eckloni and G. e. scoliostomus) of the schizothoracine Gymnocypris fish species complex from a small glacier lake in the Tibetan Plateau, Lake Sunmcuo, fit several of the key characteristics of the sympatric speciation model. We used combined mitochondrial control region sequences and the cytochrome b gene (1894 bp) to address the phylogenetics and population genetics of 232 specimens of G. e. eckloni and G. e. scoliostomus, as well as all of its closely related sister species. We found that: (i) a total of four old lineages were uncovered in the widespread G. e. eckloni, of which only one was shown to be shared with all G. e. scoliostomus individuals and (ii) the new subspecies (G. e. scoliostomus) evolved in Lake Sunmcuo from the ancestral G. e. eckloni population within approximately 0.057 Ma. These two taxa of the species complex are morphologically distinct, and reproductive isolation is further suggested. Ecological disruptive selection based on morphological traits (e.g. mouth cleft characters) and food utilization may be a mechanism of incipient speciation of two sympatric populations within Lake Sunmcuo. This study provides the first genetic evidence for sympatric speciation in the schizothoracine fish.
