Department of Biogeography, Universität Trier, Germany.
Department of Biological Sciences, National University of Singapore, Singapore.
Mol Phylogenet Evol. 2022 Oct;175:107564. doi: 10.1016/j.ympev.2022.107564. Epub 2022 Jul 3.
Adaptive radiation provides the ideal context for identifying and testing the processes that drive evolutionary diversification. However, different adaptive radiations show a variety of different patterns, making it difficult to come up with universal rules that characterize all such systems. Diversification may occur via several mechanisms including non-adaptive divergence, adaptation to novel environments, or character displacement driven by competition. Here, we characterize the ways these different drivers contribute to present-day diversity patterns, using the exemplary adaptive radiation of Hawaiian long-jawed orbweaver (Tetragnatha) spiders. We present the most taxonomically comprehensive phylogenetic hypothesis to date for this group, using 10 molecular markers and representatives from every known species across the archipelago. Among the lineages that make up this remarkable radiation, we find evidence for multiple diversification modalities. Several clades appear to have diversified in allopatry under a narrow range of ecological conditions, highlighting the role of niche conservatism in speciation. Others have shifted into new environments and evolved traits that appear to be adaptive in those environments. Still others show evidence for character displacement by close relatives, often resulting in convergent evolution of stereotyped ecomorphs. All of the above mechanisms seem to have played a role in giving rise to the exceptional diversity of morphological, ecological and behavioral traits represented among the many species of Hawaiian Tetragnatha. Taking all these processes into account, and testing how they operate in different systems, may allow us to identify universal principles underlying adaptive radiation.
适应辐射为识别和测试驱动进化多样化的过程提供了理想的背景。然而，不同的适应辐射表现出各种不同的模式，使得很难提出能够描述所有此类系统的通用规则。多样化可能通过几种机制发生，包括非适应性分歧、对新环境的适应或竞争驱动的特征位移。在这里，我们使用夏威夷长颚蛛（Tetragnatha）蜘蛛的典型适应辐射来描述这些不同驱动因素对当今多样性模式的贡献方式。我们使用 10 个分子标记和来自群岛上每个已知物种的代表，提出了迄今为止该组最具分类学全面性的系统发育假说。在构成这一非凡辐射的谱系中，我们发现了多种多样化模式的证据。几个分支似乎在生态条件狭窄的情况下异地多样化，突出了生态位保守性在物种形成中的作用。其他分支则进入了新的环境，并进化出了在这些环境中似乎具有适应性的特征。还有一些分支表现出由近亲引起的特征位移的证据，通常导致刻板的生态形态的趋同进化。所有上述机制似乎都在导致夏威夷 Tetragnatha 许多物种中表现出的形态、生态和行为特征的非凡多样性方面发挥了作用。考虑到所有这些过程，并测试它们在不同系统中的运作方式，可能使我们能够确定适应辐射的基础普遍原则。
