Department of Zoology, University of Otago, Dunedin 9054, New Zealand.
Int J Parasitol. 2012 Sep;42(10):939-46. doi: 10.1016/j.ijpara.2012.07.010. Epub 2012 Aug 23.
A reproductive division of labour has recently been discovered within polyembryonic colonies of two species of parasitic trematodes infecting snail hosts. In these colonies, one morph expands the colony through asexual reproduction while the other morph never reproduces. As in other polyembryonic species using a division of labour (parasitoid wasps, one species of sea anemone), the non-reproducing morph appears specialized for defense against competing colonies. In this study, we first assessed competition between Philophthalmus sp. (which possesses reproducing and non-reproducing morphs) and the most common co-infecting species, Maritrema novaezealandensis, by quantifying colony success within snail hosts. Colonies of either species that did not compete within their host were more successful (i.e., produced more transmission stages) than colonies that were competing in a shared host. Second, we cultured individuals of both species in vitro, alone or together, to study the interaction more closely and to measure any advantage obtained by the colony from the non-reproducing morphs. This was done by manipulating the presence and abundance of M. novaezealandensis as well as the presence of the non-reproducing 'defensive' morph. Philophthalmus sp. colonies with both reproducing and non-reproducing morphs but without M. novaezealandensis were most successful. This implies the non-reproducing morphs provide a fitness benefit to Philophthalmus sp. colonies even in the absence of competition, although the nature of this advantage remains unclear.
最近在感染蜗牛宿主的两种寄生吸虫的多胚群体中发现了生殖分工。在这些群体中，一种形态通过无性繁殖来扩大群体，而另一种形态则从不繁殖。与其他使用分工的多胚物种（寄生蜂、一种海葵）一样，不繁殖的形态似乎专门用于抵御竞争群体。在这项研究中，我们首先通过量化蜗牛宿主内群体的成功来评估 Philophthalmus sp.（具有繁殖和不繁殖形态）与最常见的共同感染物种 Maritrema novaezealandensis 之间的竞争。在宿主内不竞争的任何物种的群体比在共享宿主中竞争的群体更成功（即产生更多的传播阶段）。其次，我们在体外单独或一起培养这两个物种的个体，以更密切地研究相互作用，并测量群体从不繁殖形态中获得的任何优势。这是通过操纵 M. novaezealandensis 的存在和丰度以及非繁殖“防御”形态的存在来实现的。具有繁殖和不繁殖形态但没有 M. novaezealandensis 的 Philophthalmus sp. 群体最为成功。这意味着即使在没有竞争的情况下，不繁殖的形态也为 Philophthalmus sp. 群体提供了适应性优势，尽管这种优势的性质尚不清楚。
