Did the Sunda-Sahul Biotic Exchange result in plant diversification? A case study of switching disperser communities and fruit traits in Aglaia (Meliaceae)

巽他大陆架（包括马来西亚半岛，文莱和印度尼西亚部分地区）和萨胡尔大陆架（包括澳大利亚和新几内亚）首次碰撞25 Mya。这种碰撞首次促进了在各个大陆架上孤立进化的生物群的交换。这种“Sunda-Sahul生物交换”对该地区的生物多样性产生了重大影响，但仍然存在一个关键问题，即这种交换是否推动了生物区系的多样化。跨越大陆架的血统暴露在新的选择压力下，我们假设这导致了性状的分歧。为了验证这一假设，我们正在寻求资金进行一个案例研究的效果桑达Sahul生物交换的果实性状在米仔兰（楝科）。米仔兰属（Aglaia）为C. 127种热带树种分布在巽他和萨胡尔大陆架上，其果实具有显著的多样性。据报道，物种被灵长类动物、飞鸟或不会飞的食火鸡传播。鉴于整个巽他群岛和Sahul大陆架上的分散群落存在明显差异，特别是Sahul没有灵长类动物，我们的目标是测试不同的分散群落是否驱动了Aglaia水果性状的多样性，因为它在巽他群岛和Sahul大陆架上迁移。为此，我们打算在三年内实现三个主要目标。首先，我们将产生一个强大的，物种完整的Aglaia和相关属使用下一代测序的目标基因座使用定制诱饵试剂盒。其次，我们将通过对植物标本馆和野外采集的标本进行发育、解剖和化学分析，对米仔兰果实进行深入的表征。然后，在系统发育框架内重建米仔兰属的果实性状进化。第三，我们将实施尖端的分析，以测试是否开关水果形态的差异，分散社区。这将首先通过重建Aglaia的地理历史，并使用系统发育比较模型来测试地理跳跃是否与果实性状开关相关。在此之后，我们将在新的生态进化模拟引擎gen 3sis中建立一个空间上明确的机制模型，明确测试新地理区域中分散群落的差异是否导致果实性状多样化，并排除它是由于其他非生物因素（如气候）或中性过程（如遗传漂变）的可能性。最终，该项目将为Sunda-Sahul生物交换和全球其他类似的生物交换活动提供新的见解，并揭示导致超级多样性热点多样性演变的过程。

The Sunda continental shelf (including Peninsular Malaysia, Brunei and parts of Indonesia) and Sahul continental shelf (including Australia and New Guinea) collided for the first time 25 Mya. This collision for the first time facilitated the exchange of biotas that had evolved in isolation on each shelf. This “Sunda-Sahul Biotic Exchange” had a significant effect on the biodiversity of the region, but a key question remaining is whether the exchange drove the diversification of biota. Lineages that jumped continental shelves were exposed to novel selection pressures, and we hypothesise that this led to the divergence of traits. To test this hypothesis, we are seeking funding to conduct a case study on the effect of the Sunda-Sahul Biotic Exchange on fruit traits in Aglaia (Meliaceae). Aglaia is a genus of c. 127 tropical tree species distributed across the Sunda and Sahul shelves, with remarkable diversity in fruits. Species have been reported to be dispersed either by primates, flying birds, or the flightless cassowary. Given the stark differences in disperser communities across the islands of the Sunda and Sahul shelves – and particularly the absence of primates on Sahul – we aim to test whether the different disperser communities drove the diversity of fruit traits in Aglaia as it migrated across the Sunda and Sahul shelves. To do this, we intend to achieve three main objectives over three years. Firstly, we will generate a robust, species-complete phylogeny of Aglaia and related genera using next-generation sequencing of targeted loci using a custom bait-kit. Secondly, we will conduct an in-depth characterisation of Aglaia fruits through developmental, anatomical and chemical analyses conducted on herbarium and field-collected specimens. Fruit trait evolution in Aglaia will then be reconstructed in a phylogenetic framework. Thirdly, we will implement cutting-edge analyses to test whether switches in fruit morphology were driven by differences in disperser communities. This will be done initially by reconstructing the biogeographic history of Aglaia and using phylogenetic comparative models to test whether biogeographic jumps are correlated with fruit trait switches. Subsequent to this, we will build a spatially explicit mechanistic model in the new eco-evolutionary simulation engine gen3sis, to explicitly test whether the differences in disperser communities in new biogeographic areas are causing fruit trait diversification, and exclude the possibility that it is due to other abiotic factors such as climate, or neutral processes such as genetic drift. Ultimately, this project will give new insight into the Sunda-Sahul Biotic Exchange and other similar biotic exchange events worldwide, and shed light on the processes leading to the evolution of diversity in a megadiverse hotspot.