Natural History Museum, Cromwell Road, London SW7 5BD, UK; Australian National University, Division of Ecology & Evolution, Linnaeus Way, Canberra, ACT 2600, Australia.
Monash University, School of Biological Sciences, Wellington Road, Melbourne, VIC 3800, Australia.
Curr Biol. 2024 Sep 9;34(17):3905-3916.e5. doi: 10.1016/j.cub.2024.07.039. Epub 2024 Aug 12.
Animal phenotypes evolve and diverge as a result of differing selective pressures and drift. These processes leave unique signatures in patterns of trait evolution, impacting the tempo and mode of morphological macroevolution. While there is a broad understanding of the history of some organismal traits (e.g., body size), there is little consensus about the evolutionary mode of most others. This includes the relative contribution of prolonged (Darwinian gradualist) and episodic (Simpsonian jump) changes toward the evolution of novel morphologies. Here, we use new exon-capture and linear morphological datasets to investigate the tempo and mode of morphological evolution in Australo-Melanesian Tiliquini skinks. We generate a well-supported time-calibrated phylogenomic tree from ∼400 nuclear markers for more than 100 specimens, including undescribed diversity, and provide unprecedented resolution of the rapid Miocene diversification of these lizards. By collecting a morphological dataset that encompasses the lizard body plan (19 traits across the head, body, limb, and tail), we are able to identify that most traits evolve conservatively, but infrequent evolutionary bursts result in morphological novelty. These phenotypic discontinuities occur via rapid rate increases along individual branches, inconsistent with both gradualistic and punctuated equilibrial evolutionary modes. Instead, this "punctuated gradualism" has resulted in the rapid evolution of blue-tongued giants and armored dwarves in the ∼20 million years since colonizing Australia. These results outline the evolutionary pathway toward new morphologies and highlight the heterogeneity of evolutionary tempo and mode, even within individual traits.
动物表型的进化和分化是由于不同的选择压力和漂变造成的。这些过程在性状进化的模式中留下了独特的特征，影响了形态宏观进化的速度和模式。虽然人们对某些生物体特征的历史（例如，体型）有广泛的了解，但对于大多数其他特征的进化模式却没有达成共识。这包括长时间（达尔文渐进主义者）和偶发（辛普森式跳跃）变化对新形态进化的相对贡献。在这里，我们使用新的外显子捕获和线性形态数据集来研究澳大利亚-美拉尼西亚 Tiliquini 石龙子的形态进化速度和模式。我们从超过 100 个样本的 400 多个核标记中生成了一个经过充分支持的时间校准的系统发育树，包括未描述的多样性，并为这些蜥蜴在中新世的快速多样化提供了前所未有的分辨率。通过收集一个涵盖蜥蜴体型的形态数据集（头部、身体、四肢和尾巴的 19 个特征），我们能够确定大多数特征进化保守，但偶尔的进化爆发会导致形态新颖。这些表型不连续性是通过个别分支上的快速速率增加产生的，这与渐进主义和间断平衡进化模式都不一致。相反，这种“间断渐进主义”导致了在大约 2000 万年前澳大利亚殖民后，蓝舌巨蜥和装甲矮人快速进化。这些结果勾勒出了通向新形态的进化途径，并强调了即使在单个特征中，进化速度和模式的异质性。
