Data from: Adaptive radiation and ecological opportunity in Sulawesi and Philippine fanged frog (Limnonectes) communities.

Because island communities are derived from the mainland, they are often less diverse by comparison. However, reduced complexity of island communities can also present ecological opportunities. For example, amphibian diversity on the Indonesian island of Sulawesi is generally lower than in the Philippines, but this island supports a surprisingly diverse endemic assemblage of Sulawesi fanged frogs (genus Limnonectes). To explore evolutionary dynamics of this system, we examined molecular, morphological, and geographical variation of fanged frogs from these two regions. Using genealogical concordance – a conservative standard – we identified 12 species on Sulawesi, only four of which are described. One more species can be distinguished with morphology, and a Bayesian approach to species delimitation suggests our total species estimate on Sulawesi (n = 13) is still an underestimate. After accounting for evolutionary history, a model with multiple body size optima in sympatric Limnonectes species is significantly preferred over a “random walk” model where body size evolves by Brownian motion. Additionally, morphological variation is higher among sympatric than non-sympatric species on Sulawesi, but not in the Philippines. Taken together, these findings suggest that adaptive radiation of fanged frogs on Sulawesi was driven by natural selection to infiltrate ecological niches occupied by other lineages in the Philippines. Our study supports the concept of ecological opportunity in community assembly: diversification in mature communities, such as the Philippines, is limited by a dearth of unoccupied ecological niches. On Sulawesi however, evolutionary novelties originated in a predictable and replicated fashion in response to opportunities presented by a depauperate ancestral community.

由于岛屿群落（island communities）均源自大陆，其物种多样性通常较大陆群落更低。然而，物种组成简化的岛屿群落也可带来生态机遇。例如，印尼苏拉威西岛（Sulawesi）的两栖动物多样性整体低于菲律宾，但该岛孕育了物种丰富度颇高的特有苏拉威西牙蛙（Sulawesi fanged frogs，Limnonectes属）类群。为探究该系统的演化动态，我们分析了这两个区域牙蛙的分子、形态及地理变异特征。采用谱系一致性（genealogical concordance）这一保守判定标准，我们在苏拉威西岛共鉴定出12个物种，其中仅4个已有正式分类描述。另有1个物种可通过形态特征予以区分，而用于物种界定（species delimitation）的贝叶斯（Bayesian）分析方法显示，我们对苏拉威西岛物种总数的估计值（n=13）仍属低估。在考虑演化历史因素后，相较于描述体型演化遵循布朗运动（Brownian motion）的"random walk"模型，纳入同域分布（sympatric）Limnonectes属物种多体型最优值的模型获得了显著更高的统计支持度。此外，苏拉威西岛的同域分布物种间形态变异程度显著高于非同域物种，但菲律宾的类群并未呈现这一模式。综合以上研究结果，苏拉威西岛牙蛙的适应辐射（adaptive radiation）是受自然选择（natural selection）驱动，以填补菲律宾地区其他演化支系（lineages）所占据的生态位（ecological niches）。本研究支持群落构建（community assembly）中的生态机遇理论：成熟群落（如菲律宾的群落）的物种分化受限于未占据生态位的匮乏；而在苏拉威西岛，演化新性状以可预测且可重复的方式起源，以响应物种贫乏的祖先群落所提供的生态机遇。