Weeks Stephen C, Sanderson Thomas F, Reed Sadie K, Zofkova Magdalena, Knott Brenton, Balaraman Usha, Pereira Guido, Senyo Diana M, Hoeh Walter R
Department of Biology, The University of Akron, Akron, OH 44325-3908, USA.
Proc Biol Sci. 2006 Mar 22;273(1587):725-34. doi: 10.1098/rspb.2005.3370.
Among the variety of reproductive mechanisms exhibited by living systems, one permutation--androdioecy (mixtures of males and hermaphrodites)--is distinguished by its rarity. Models of mating system evolution predict that androdioecy should be a brief stage between hermaphroditism and dioecy (separate males and females), or vice versa. Herein we report evidence of widespread and ancient androdioecy in crustaceans in the genus Eulimnadia, based on observations of over 33,000 shrimp from 36 locations from every continent except Antarctica. Using phylogenetic, biogeographical and palaeontological evidence, we infer that androdioecy in Eulimnadia has persisted for 24-180 million years and has been maintained through multiple speciation events. These results suggest that androdioecy is a highly successful aspect of the life history of these freshwater crustaceans, and has persisted for orders of magnitude longer than predicted by current models of this rare breeding system.
在生命系统所展现出的各种繁殖机制中，一种排列方式——雄花两性同体（雄性与雌雄同体的混合）——因其罕见而显得与众不同。交配系统进化模型预测，雄花两性同体应该是雌雄同体和雌雄异体（雄性和雌性分开）之间的一个短暂阶段，反之亦然。在此，我们基于对除南极洲外各大洲36个地点的33000多只虾的观察，报告了Eulimnadia属甲壳类动物中广泛且古老的雄花两性同体现象的证据。利用系统发育、生物地理和古生物学证据，我们推断Eulimnadia属的雄花两性同体现象已经持续了2.4亿至1.8亿年，并且通过多次物种形成事件得以维持。这些结果表明，雄花两性同体是这些淡水甲壳类动物生活史中一个非常成功的方面，并且持续的时间比目前关于这种罕见繁殖系统的模型所预测的要长得多。
