Zoological State Collection Münchhausenstraße 21, Munich, 81247, Germany.
Ecol Evol. 2013 Apr;3(4):1031-49. doi: 10.1002/ece3.517. Epub 2013 Mar 7.
The Australasian archipelago is biologically extremely diverse as a result of a highly puzzling geological and biological evolution. Unveiling the underlying mechanisms has never been more attainable as molecular phylogenetic and geological methods improve, and has become a research priority considering increasing human-mediated loss of biodiversity. However, studies of finer scaled evolutionary patterns remain rare particularly for megadiverse Melanesian biota. While oceanic islands have received some attention in the region, likewise insular mountain blocks that serve as species pumps remain understudied, even though Australasia, for example, features some of the most spectacular tropical alpine habitats in the World. Here, we sequenced almost 2 kb of mitochondrial DNA from the widespread diving beetle Rhantus suturalis from across Australasia and the Indomalayan Archipelago, including remote New Guinean highlands. Based on expert taxonomy with a multigene phylogenetic backbone study, and combining molecular phylogenetics, phylogeography, divergence time estimation, and historical demography, we recover comparably low geographic signal, but complex phylogenetic relationships and population structure within R. suturalis. Four narrowly endemic New Guinea highland species are subordinated and two populations (New Guinea, New Zealand) seem to constitute cases of ongoing speciation. We reveal repeated colonization of remote mountain chains where haplotypes out of a core clade of very widespread haplotypes syntopically might occur with well-isolated ones. These results are corroborated by a Pleistocene origin approximately 2.4 Ma ago, followed by a sudden demographic expansion 600,000 years ago that may have been initiated through climatic adaptations. This study is a snapshot of the early stages of lineage diversification by peripatric speciation in Australasia, and supports New Guinea sky islands as cradles of evolution, in line with geological evidence suggesting very recent origin of high altitudes in the region.
由于具有高度复杂的地质和生物进化历程，澳大利亚群岛的生物多样性极其丰富。随着分子系统发育和地质方法的不断改进，揭示其中的潜在机制变得更加可行，并且在考虑到生物多样性因人类活动而不断丧失的情况下，这已经成为一个研究重点。然而，对于具有高度多样性的美拉尼西亚生物群，关于更精细进化模式的研究仍然很少。尽管该地区的海洋岛屿已经受到了一些关注，但作为物种泵的岛屿山地块同样也未得到充分研究，即使澳大利亚拥有世界上一些最壮观的热带高山生境。在这里，我们对分布在整个澳大利亚和印度-马来亚群岛（包括遥远的新几内亚高地）的广泛潜水甲虫 Rhantus suturalis 进行了近 2 kb 的线粒体 DNA 测序。基于专家分类学和多基因系统发育主干研究，结合分子系统发育、系统地理学、分化时间估计和历史人口动态学，我们发现地理信号相对较低，但在 R. suturalis 内部存在复杂的系统发育关系和种群结构。四个狭窄特有的新几内亚高地物种被归入下属地位，两个种群（新几内亚、新西兰）似乎构成了正在进行的物种形成案例。我们揭示了对遥远山脉的反复殖民，其中核心分支的单倍型与高度隔离的单倍型在同域中可能出现。这些结果得到了大约 240 万年前上新世起源的支持，随后在 60 万年前发生了突然的人口扩张，这可能是通过气候适应而引发的。本研究是澳大利亚周边地区通过边缘物种形成进行谱系多样化的早期阶段的一个快照，并支持新几内亚天空岛屿作为进化的摇篮，这与地质证据一致，表明该地区的高海拔地区是最近才出现的。
