Anatomy of an adaptive radiation: a unique reproductive strategy in the endemic freshwater gastropod Tylomelania (Cerithioidea: Pachychilidae) on Sulawesi, Indonesia and its biogeographical implications
Anatomy of an adaptive radiation: a unique reproductive strategy in the endemic freshwater gastropod Tylomelania (Cerithioidea: Pachychilidae) on Sulawesi, Indonesia and its biogeographical implications
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适应性辐射的解剖：印度尼西亚苏拉威西岛特有淡水腹足动物 Tylomelania（Cerithioidea：Pachychilidae）的独特繁殖策略及其生物地理学意义
DOI：
10.1111/j.1095-8312.2005.00515.x
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发表时间：
2005
影响因子：
1.9
通讯作者：
M. Glaubrecht
中科院分区：
文献类型：
--
作者：
T. Rintelen;M. Glaubrecht
古湖泊的适应性辐射模式为物种形成和适应机制提供了有价值的线索。与脊椎动物（例如鱼类或雀类）的辐射相比，无脊椎动物种群在很大程度上被忽视了。虽然分子数据的增加缩小了这一差距，但在进化假设的背景下解释这些数据的解剖学基础仍然广泛缺乏。在这里，我们评估了在印度尼西亚苏拉威西岛古代湖泊中广泛辐射的淡水腹足动物Tylomelania的解剖学发现；我们的目标是将这些数据与最近获得的分子系统发育证据相协调。一个多世纪前发现的物种和表型多样化的物种群，目前描述的34个分类群，只是偶尔被引用为古代湖泊适应性辐射的例子，而解剖学数据则完全缺乏。我们对解剖特征的研究表明，在物种水平上，定性变异非常低。因此，与先前的观点相反，我们认为存在一个单一的单系谱系特有于这个岛。巨蟹最显著的特征是它的子宫孵化策略，即在苍白的输卵管中保留卵子和胚胎。这在东南亚厚皮菊科中是独一无二的。在子宫育儿袋内，由一个非常大的白蛋白腺产生的大量营养物质包围着后代，胚胎不断地产生。一些种类的有壳幼体是迄今为止已知的胎生腹足类动物中最大的，在孵化时几乎有2厘米长。Tylomelania的这种生殖特征的组合，以大量的母体投入为特征，被认为是卵胎生的，使其孵化策略在其他腹足类动物中也是独一无二的。此外，我们的数据拒绝了先前假设的与其他东南亚pachychilids的密切关系，而是表明北澳大利亚假不达米亚是Tylomelania的姐妹群。这些发现对在进化和生物地理背景下对铁蜥的形态特征进行系统发育解释具有重要意义，从而导致两属的共同祖先起源于澳大利亚北部大陆边缘的假设。©2005伦敦林奈学会，林奈学会生物学杂志，2005,85,513-542。
The patterns of adaptive radiations in ancient lakes provide valuable clues to mechanisms of speciation and adaptation. In contrast to vertebrate radiations, for instance in fishes or finches, invertebrate species flocks have been largely neglected. While the increase in molecular data narrows this gap, the anatomical basis for interpreting these data against the background of evolutionary hypotheses is still widely lacking. Here we evaluate anatomical findings in the live-bearing pachychilid freshwater gastropod Tylomelania, which has radiated extensively in ancient lakes in the Indonesian island, Sulawesi; we have aimed at reconciling these data with recently obtained molecular phylogenetic evidence. Discovered more than a century ago, the speciose and phenotypically diverse species flock with 34 currently described taxa was only occasionally cited as an example of adaptive radiation in ancient lakes, while anatomical data were entirely lacking. Our study of anatomical characters reveals very low qualitative variation at the species level. Thus, contrary to earlier views we suggest the existence of a single monophyletic lineage endemic to this island. The most conspicuous feature of Tylomelania is its uterine brooding strategy, i.e. retaining eggs and embryos in the pallial oviduct. This is unique among South-East Asian pachychilids. Within the uterine brood pouch the offspring is surrounded by considerable amounts of nutritive material produced by a very large albumin gland, and the embryos are produced continuously. The shelled juveniles of some species are the largest known so far in viviparous gastropods, measuring almost 2 cm in length when hatching. This combination of reproductive features in Tylomelania, characterized by a high amount of maternal investment, is considered to be ovoviviparous, rendering its brooding strategy unique also among other gastropods. In addition, our data reject a previously assumed close relationship to other South-East Asian pachychilids and instead suggest the North Australian Pseudopotamis as sister group to Tylomelania. These findings have significant consequences for the phylogenetic interpretation of morphological characters of Tylomelania in an evolutionary and biogeographical context, leading to the hypothesis that the common ancestor of both genera originated somewhere on the northern Australian continental margin. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 85, 513–542.