Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, 66046, USA.
Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Borok, Nekouzsky District, Yaroslavl Oblast, 152742, Russia.
Sci Rep. 2017 Aug 22;7(1):8619. doi: 10.1038/s41598-017-08403-1.
The temporal origin of Madagascar's extraordinary endemic diversity is debated. A preference for Cenozoic dispersal origins has replaced the classical view of Mesozoic vicariance in the wake of molecular dating. However, evidence of ancient origins is mounting from arthropod groups. Using phylogenetic 'tip-dating' analysis with fossils, we show that a whirligig beetle species, Heterogyrus milloti, inhabiting forest streams in southeastern Madagascar is the last survivor of a once dominant and widespread Mesozoic group. With a Late Triassic to Early Jurassic origin (226-187 Ma) it is the hitherto oldest dated endemic lineage of animal or plant on Madagascar. Island biotas' sensitivity to extinction is well known, but islands can also provide refuge from continental extinction. Heterogyrus milloti is an irreplaceable link to the freshwater biota of the Mesozoic and serves as a reminder of what may be lost without critical conservation efforts on Madagascar.
马达加斯加非凡的特有生物多样性的时间起源存在争议。随着分子定年法的出现，中生代隔离起源的经典观点已经被新生代扩散起源所取代。然而，节肢动物类群的古老起源的证据越来越多。利用带有化石的系统发育“末梢日期推断”分析，我们表明，一种生活在马达加斯加东南部森林溪流中的旋叶甲属（Heterogyrus）物种 Heterogyrus milloti 是曾经占主导地位和广泛分布的中生代群体的最后幸存者。其起源于晚三叠世至早侏罗世（226-187 Ma），是迄今为止在马达加斯加发现的最古老的动物或植物特有谱系。岛屿生物群对灭绝的敏感性是众所周知的，但岛屿也可以为大陆灭绝提供避难所。Heterogyrus milloti 是中生代淡水生物群的一个不可替代的联系，它提醒人们，如果不在马达加斯加进行关键的保护工作，可能会失去什么。
