Modes of speciation in Indonesian terrestrial arthropods

虽然热带生物的生物多样性最丰富，但我们对热带生物物种形成现象的了解仍然很少。在本研究中，我们试图阐明印度尼西亚从东方地区延伸到澳大利亚地区的几组陆生节肢动物的物种形成模式。特别关注被称为Wallacea的两个动物地理区域边界上的动物区系变化。我们对以下岛屿进行了调查：苏门答腊岛(西苏门答腊岛)、爪哇岛(全岛)和巴厘岛属于马来大陆，龙目岛、松巴哇岛和苏拉威西岛(东北部、中部和南部)属于Wallacea。不幸的是，由于政治原因，无法调查预定研究地点的东部地区，包括Irian Jaya。在三年调查的最后一年中，我们还考察了被称为东南亚热带和亚热带交界处的马来半岛库拉地峡的一些昆虫群。不同动物群的区系变化模式似乎不同。例如，虽然Espachnine瓢虫在东方和澳大利亚地区表现出不同的动物群，而且在苏拉威西有相当独特的动物区系，但对于流动性较高的群居黄蜂来说，没有这种地理差异。另一方面，收割者和千足虫的物种数量向东减少，可能是受到日益干旱的影响。此外，我们还发现了几个可能的寄主小种或寄主相关的兄弟种(共生物种的候选者)的案例，并能够进行实验室实验来检验一些物种的表现和偏好。这些研究将有助于我们更好地了解热带昆虫和其他节肢动物的物种形成模式。

Although it has been well recognized that the biodiversity is richest in tropics, our knowledge on the speciation phenomena in tropical organisms is still poor. In the present study, we tried to elucidate the modes of speciation in several groups of terrestrial arthropods in Indonesia, which stretches from the Oriental region to the Australian region. Particular attention has been paid to the faunal change across the boundary of the two zoogeographic regions known as Wallacea. The following islands have been investigated by us: Sumatra (West Sumatra), Java (all the island) and Bali, belonging to the Malesia land mass; Lombok, Sumbawa and Sulawesi (northeastern part, central part, and southern part) belonging to Wallacea. Unfortunately, the eastern parts of the intended study sites, including Irian Jaya, could not be investigated owing to political reasons. In the last year of the three years survey, we have also examined some groups of insects in the Kura isthmus in the Malay Peninsula, which is known as the boundary of tropic and sub-tropic zones in the Southeast Asia.Patterns of the faunal change across Wallacea seemed different according to the groups of animals. For example, while epilachnine ladybirds showed different faunas in the Oriental and Australia regions, and furthermore, there is a rather characteristic fauna in Sulawesi, no such geographic divergence was suggested for social wasps with high mobility. On the other hand, harvestmen and millipedes decreased in the number of species eastward, possibly affected by increasing aridity. Furthermore, we have discovered several cases of putative host races or host related sibling species (candidates of sympatrically speciated species) in epilachnine ladybird beetles, and were able to perform laboratory experiments to examine performance and preference of some species. These studies will contribute to our better understanding of the mode of speciation in tropical insects and other arthropods.