Gippner Sven, Travers Scott L, Scherz Mark D, Colston Timothy J, Lyra Mariana L, Mohan Ashwini V, Multzsch Malte, Nielsen Stuart V, Rancilhac Loïs, Glaw Frank, Bauer Aaron M, Vences Miguel
Zoological Institute, Technical University of Braunschweig, Mendelssohnstr. 4, 38106 Braunschweig, Germany; State Natural History Museum of Braunschweig, Pockelsstr. 10, 38106 Braunschweig, Germany.
Department of Biological Sciences, Rutgers University-Newark, 195 University Avenue, Newark, NJ 07102, USA.
Mol Phylogenet Evol. 2021 Dec;165:107311. doi: 10.1016/j.ympev.2021.107311. Epub 2021 Sep 14.
The 71 currently known species of dwarf geckos of the genus Lygodactylus are a clade of biogeographic interest due to their occurrence in continental Africa, Madagascar, and South America. Furthermore, because many species are morphologically cryptic, our knowledge of species-level diversity within this genus is incomplete, as indicated by numerous unnamed genetic lineages revealed in previous molecular studies. Here we provide an extensive multigene phylogeny covering 56 of the named Lygodactylus species, four named subspecies, and 34 candidate species of which 19 are newly identified in this study. Phylogenetic analyses, based on ∼10.1 kbp concatenated sequences of eight nuclear-encoded and five mitochondrial gene fragments, confirm the monophyly of 14 Lygodactylus species groups, arranged in four major clades. We recover two clades splitting from basal nodes, one comprising exclusively Malagasy species groups, and the other containing three clades. In the latter, there is a clade with only Madagascar species, which is followed by a clade containing three African and one South American species groups, and its sister clade containing six African and two Malagasy species groups. Relationships among species groups within these latter clades remain weakly supported. We reconstruct a Lygodactylus timetree based on a novel fossil-dated phylotranscriptomic tree of squamates, in which we included data from two newly sequenced Lygodactylus transcriptomes. We estimate the crown diversification of Lygodactylus started at 46 mya, and the dispersal of Lygodactylus among the main landmasses in the Oligocene and Miocene, 35-22 mya, but emphasize the wide confidence intervals of these estimates. The phylogeny suggests an initial out-of-Madagascar dispersal as most parsimonious, but accounting for poorly resolved nodes, an out-of-Africa scenario may only require one extra dispersal step. More accurate inferences into the biogeographic history of these geckos will likely require broader sampling of related genera and phylogenomic approaches to provide better topological support. A survey of morphological characters revealed that most of the major clades and species groups within Lygodactylus cannot be unambiguously characterized by external morphology alone, neither by unique character states nor by a diagnostic combination of character states. Thus, any future taxonomic work will likely benefit from integrative, phylogenomic approaches.
目前已知的71种细趾虎属侏儒壁虎是一个具有生物地理学研究价值的进化枝，因为它们分布在非洲大陆、马达加斯加和南美洲。此外，由于许多物种在形态上难以区分，我们对该属物种水平多样性的了解并不完整，正如先前分子研究中揭示的众多未命名的遗传谱系所表明的那样。在此，我们提供了一个广泛的多基因系统发育树，涵盖了56种已命名的细趾虎属物种、4个已命名的亚种以及34个候选物种，其中19个是在本研究中首次鉴定出来的。基于8个核编码基因片段和5个线粒体基因片段拼接而成的约10.1千碱基对序列进行的系统发育分析，证实了14个细趾虎属物种组的单系性，这些物种组分为四个主要进化枝。我们发现两个进化枝从基部节点处分开，一个仅包含马达加斯加物种组，另一个包含三个进化枝。在后者中，有一个仅包含马达加斯加物种的进化枝，随后是一个包含三个非洲物种组和一个南美洲物种组的进化枝，其姐妹进化枝包含六个非洲物种组和两个马达加斯加物种组。这些后分支内物种组之间的关系支持度较弱。我们基于一个新的有化石定年的有鳞目系统发育转录组树重建了细趾虎属的时间树，其中我们纳入了来自两个新测序的细趾虎属转录组的数据。我们估计细趾虎属的冠群多样化始于4600万年前，并且在渐新世和中新世（3500 - 2200万年前）细趾虎属在主要陆块之间扩散，但强调这些估计的置信区间较宽。系统发育树表明，最简约的情况是最初从马达加斯加向外扩散，但考虑到节点分辨率较差，从非洲向外扩散的情况可能只需要多一个扩散步骤。要更准确地推断这些壁虎的生物地理历史，可能需要对相关属进行更广泛的采样，并采用系统发育基因组学方法来提供更好的拓扑支持。对形态特征的调查表明，细趾虎属内的大多数主要进化枝和物种组仅通过外部形态无法明确区分，无论是通过独特的特征状态还是特征状态的诊断组合都不行。因此，未来的任何分类学工作可能都将受益于综合的系统发育基因组学方法。
