Craddock Elysse M, Kambysellis Michael P, Franchi Lisa, Francisco Peter, Grey Marques, Hutchinson Angela, Nanhoo Shawn, Antar Shyar
Purchase College, State University of New York, Purchase, NY.
Department of Biology, New York University, New York, NY.
J Morphol. 2018 Dec;279(12):1725-1752. doi: 10.1002/jmor.20884. Epub 2018 Nov 5.
Ecological diversification of the endemic Hawaiian Drosophilidae has been accompanied by striking divergence in egg morphology, and ovarian structure and function. To determine how these flies successfully oviposit in a variety of breeding substrates, we used Scanning Electron Microscopy to examine the ultrastructure of the ovipositor of a sample of 65 Drosophila species and five Scaptomyza species of this hyperdiverse monophyletic group. The Drosophila species analyzed included representatives of the fungus-breeding haleakalae group, the leaf-breeding antopocerus and modified tarsus groups, the modified mouthparts species group, the nudidrosophila, and the picture wing clade; the latter sample of 41 species from four species groups included stem- and bark-breeders, as well as tree sap flux-breeders. Ovipositor length was found to vary more than 12-fold among Hawaiian drosophilids, with the longest ovipositors observed in the bark-breeding species and the shortest among the Scaptomyza and fungus-breeders. More noteworthy is the striking variation in overall shape and proportions of the ovipositor, in the shape of the apical region, and in the pattern of sensory structures or ovisensilla. Ultrastructural observations of the pair of long subapical sensilla on the ventral side identify these, for the first time, as taste bristles. Ovipositor form correlates strongly with the oviposition substrate used by the species, being of a distinctive shape and size in each case. We infer that the observed morphological divergence in the ovipositor is adaptive and the product of natural selection for successful reproduction in alternate microhabitats. The array of ovipositor forms that have evolved among the Hawaiian Drosophila species represent a series of ecomorphs that along with other divergent traits of the female reproductive system, have contributed to the successful adaptive radiation of this remarkable fauna.
夏威夷特有的果蝇科的生态多样化伴随着卵形态、卵巢结构和功能的显著差异。为了确定这些果蝇如何在各种繁殖基质中成功产卵，我们使用扫描电子显微镜检查了这个高度多样化的单系类群中65种果蝇和5种黑腹果蝇的产卵器超微结构。所分析的果蝇物种包括真菌繁殖的哈雷阿卡拉果蝇组、叶繁殖的蚁果蝇和跗节变异组、口器变异物种组、裸果蝇以及图像翅类群的代表；后一组来自四个物种组的41个物种包括树干和树皮繁殖者以及树液流繁殖者。发现夏威夷果蝇科的产卵器长度变化超过12倍，在树皮繁殖物种中观察到最长的产卵器，而在黑腹果蝇和真菌繁殖者中最短。更值得注意的是产卵器的整体形状和比例、顶端区域的形状以及感觉结构或产卵感觉器的模式存在显著差异。对腹侧一对长的亚顶端感觉器的超微结构观察首次将它们确定为味觉刚毛。产卵器的形态与物种使用的产卵基质密切相关，每种情况下都具有独特的形状和大小。我们推断，观察到的产卵器形态差异是适应性的，是自然选择在不同微生境中成功繁殖的产物。夏威夷果蝇物种中进化出的一系列产卵器形态代表了一系列生态形态，它们与雌性生殖系统的其他不同特征一起，促成了这一非凡动物群的成功适应性辐射。
