Limits to Prolonged Planktonic Life among Larvae of TropicalBenthic Invertebrates and its Biogeographic Consequences

在中太平洋、大西洋和印度洋的热带上层水域，潮下无脊椎动物的远行或“远距离”幼虫的广泛存在支持这样一种假设，即幼虫不仅对海洋岛屿的初始殖民有重要贡献，更广泛地说，对这些物种目前的连续或不连续的范围有重要贡献，但也与岛屿之间、甚至岛屿与遥远的大陆人口之间持续的基因交流有关。然而，还没有人以任何系统的方式证明远洋幼虫在公海采集时能够变态。我们还不知道远洋幼虫是否在生理上适应了长时间的浮游，或者是否已经记录的缺乏进一步增长的原因是由于公海浮游植物密度较低。未来的研究将解决这两个问题：1)通过在公海获取幼虫并通过实验确定这些幼虫是否有能力变质；(2)通过在实验室保持幼虫以确定在海洋中不会变质的个体最终是否有能力变性，3)通过确定在足够的浮游植物浓度下，远洋幼虫是否在生理上能够进一步生长，或者是否达到了生长停滞，即准全浮游状态。

The widespread existence of teleplanic or "long distance" larvae of sublittoral invertebrates in the tropical epipelagic waters of the central Pacific, Atlantic and Indian Oceans supports the hypothesis that larvae contribute importantly not only to initial colonization of oceanic islands and, more generally, to the present continuous or disjunct ranges of such species, but also to the continuing genetic exchange among islands or even between islands and far distant continental populations. However, no one has yet demonstrated in any systematic way that teleplanic larvae are capable of metamorphosing at the time of their collection in the open sea. We do not yet know whether teleplanic larvae are physiologically adapted for remaining planktonic over long periods of time or whether the lack of further growth already documented instead is due to low phytoplankton concentrations in the open ocean. The future research will address these two questions 1) by obtaining larvae in the open ocean and ascertain experimentally whether or not these larvae are competent to metamorphose, (2) by maintaining larvae in the laboratory to determine whether individuals that would not metamorphose in the sea eventually become competent to metamorphose, and 3) by determining whether or not teleplanic larvae are physiologically capable of further growth given adequate phytoplankton concentrations or alternatively whether growth stasis, i.e., a quasi-holoplanktonic state, is achieved.