Whiteman Noah K
Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA.
Mol Ecol. 2008 Oct;17(20):4395-7. doi: 10.1111/j.1365-294X.2008.03938.x.
When researchers first caught a glimpse of the lush carpet of pink tubeworms covering the scattered bones of a dead grey whale 2900 m below the surface of Monterey Bay, the excitement onboard the Western Flyer (the mother ship of the remotely operated vehicle the Tiburon) must have been electrifying. The discovery of a new genus and several species of whale bone-eating Osedax tubeworms (Annelida, Siboglinidae) a mere 6 years ago from the deep sea was itself noteworthy. But what the researchers peering into the video monitors aboard the Western Flyer could not have known at that moment was that in the gelatinous tubes of those worms clung even more peculiar forms: harems of tiny, paedomorphic males of Osedax, numbering in the hundreds at times. Whereas female tubeworms bore into the marrow of whale bones (possibly via enzymes from their endosymbiotic bacteria), the dwarf males secondarily colonize the tubes of the resident females. The number of males in a female's tube increases over time in a curvilinear fashion. Dwarf males are known from all Osedax species examined to date, yet the origin of the males was an open question. In this issue, Vrijenhoek et al. provide compelling evidence that dwarf males found in the tubes of female Osedax worms are derived from a common larval pool and are unlikely to be the sons of host females or the progeny of females in the local genetic neighbourhood. This study provides an important foundation for future work on the ecology and evolution of extreme male dwarfism in Osedax and sexual size dimorphism more generally.
当研究人员首次瞥见覆盖在蒙特雷湾海面以下2900米处一头死去灰鲸散落骨骼上那片郁郁葱葱的粉色管虫地毯时，“西部飞行者号”（遥控潜水器“蒂伯龙号”的母船）上的兴奋之情肯定是令人激动不已的。仅仅在6年前，人们才从深海发现了一个新属以及几种以鲸骨为食的食骨蠕虫（环节动物门，西伯加林科），这一发现本身就值得关注。但当时在“西部飞行者号”上盯着视频监视器的研究人员不可能知道的是，在那些蠕虫的凝胶状管子里还附着着更为奇特的形态：数百只有时甚至多达数百只微小的幼态侏儒雄性食骨蠕虫的后宫群体。雌性管虫钻入鲸骨的骨髓（可能是通过其体内共生细菌产生的酶），而侏儒雄性则在常住雌性的管子里二次定殖。雌性管子里雄性的数量会随着时间呈曲线增加。到目前为止，在所有已研究的食骨蠕虫物种中都发现了侏儒雄性，但雄性的起源一直是个悬而未决的问题。在本期杂志中，弗里扬霍克等人提供了令人信服的证据，表明在雌性食骨蠕虫管子里发现的侏儒雄性源自一个共同的幼虫库，不太可能是宿主雌性的儿子或当地基因邻域内雌性的后代。这项研究为今后关于食骨蠕虫极端雄性侏儒症的生态学和进化以及更普遍的两性体型差异的研究奠定了重要基础。
