Hill Ethan C, Gao Diana F, Polhemus Dan A, Fraser Claire J, Iova Bulisa, Allison Allen, Butler Marguerite A
School of Life Sciences, University of Hawai'i, 2538 McCarthy Mall, Honolulu, 96822, HI, USA.
Department of Biology, University of San Francisco, 2130 Fulton St, Harney Science Center, San Francisco, 94117, CA, USA.
Integr Org Biol. 2023 Jul 29;5(1):obad028. doi: 10.1093/iob/obad028. eCollection 2023.
Studies of the Papuan region have provided fundamental insights into the evolutionary processes generating its exceptional biodiversity, but the influence of geological processes merits further study. Lying at the junction of five tectonic plates, this region has experienced a turbulent geological history that has not only produced towering mountains allowing elevational specialization and island archipelagos with varying degrees of isolation promoting vicariance, but also active margins where land masses have collided and been subsequently rifted apart creating a mosaic of intermixed terranes with vastly different geological histories. Asterophryine frogs are a hyperdiverse clade representing half the world's microhylid diversity (over 360 species) centered on New Guinea and its satellite islands. We show that vicariance facilitated by geological history explains this far and wide distribution of a clade that should have poor dispersal abilities. We recovered a mainland tectonic unit, the East Papua Composite Terrane (EPCT), as the center of origin for Asterophryinae and no fewer than 71 instances of what appear to be long-distance dispersal events, 29 of which are between mainland regions, with 42 from the mainland to the islands, some presently as far as 200 km away from source populations over open ocean. Furthermore, we find strong support for a "Slow and Steady" hypothesis for the formation of the northern margin of New Guinea by many separate accretion events during the Miocene, over other major geological alternatives, consistent with the 20 M year age of the clade and arrival via the EPCT. In addition, the historical biogeography of our frogs strongly supports an affiliation of the Louisiade Archipelago and Woodlark Island with the Owen Stanley Range on the EPCT, and the recent proximity of the large New Britain Island. Our results show that Asterophryinae did not have to repeatedly and independently disperse across large ocean barriers to the offshore islands, against the predictions of island biogeography theory, but that the current distribution can be explained through vicariance and short-distance oceanic dispersal as historical land connections disappeared and islands slowly became separated from each other. We show that islands have a life history, changing in distance from other land masses, with consequent opportunities for dispersal, isolation, and cladogenesis of their biotas. More broadly, we can begin to see how the geological history of the Papuan region can result in the rapid accumulation and staggering number of extant species.
对巴布亚地区的研究为产生其独特生物多样性的进化过程提供了基本见解，但地质过程的影响值得进一步研究。该地区位于五个构造板块的交界处，经历了动荡的地质历史，这不仅造就了高耸的山脉，使得物种能够在海拔高度上实现特化，还形成了不同程度隔离的岛屿群岛，促进了物种的地理隔离，而且其活跃的边缘地带，陆地板块相互碰撞，随后又裂开，形成了地质历史截然不同的混杂地块镶嵌体。星蛙科蛙类是一个高度多样化的分支，代表了全球姬蛙科多样性的一半（超过360种），以新几内亚及其附属岛屿为中心。我们发现，地质历史促成的地理隔离解释了这个本应扩散能力较差的分支为何分布如此广泛。我们确定了一个大陆构造单元，即东巴布亚复合地块（EPCT），作为星蛙亚科的起源中心，以及不少于71次看似远距离扩散事件，其中29次发生在大陆地区之间，42次从大陆到岛屿，有些目前距离源种群在公海上达200公里之远。此外，我们发现有强有力的证据支持“缓慢而稳定”假说，即中新世期间新几内亚北缘是通过多次单独的增生事件形成的，而非其他主要地质假说，这与该分支2000万年的年龄以及通过EPCT到达此地相一致。此外，我们研究的蛙类的历史生物地理学有力地支持了路易西亚德群岛和伍德拉克岛与EPCT上欧文斯坦利山脉的联系，以及大新不列颠岛最近的地理位置。我们的研究结果表明，星蛙亚科不必像岛屿生物地理学理论所预测的那样，反复独立地跨越巨大的海洋屏障扩散到近海岛屿，而是当前的分布可以通过地理隔离和短距离海洋扩散来解释——随着历史上的陆地连接消失，岛屿逐渐彼此分离。我们表明，岛屿有其生命历程，与其他陆地的距离不断变化，从而为其生物群落的扩散、隔离和物种形成带来机会。更广泛地说，我们可以开始明白巴布亚地区的地质历史是如何导致现存物种迅速积累且数量惊人的。
