Price C S, Kim C H, Gronlund C J, Coyne J A
Department of Ecology and Evolution, The University of Chicago, Illinois 60637, USA.
Evolution. 2001 Jan;55(1):81-92. doi: 10.1111/j.0014-3820.2001.tb01274.x.
Forms of reproductive isolation that act after copulation but before fertilization are potentially important components of speciation, but are studied only infrequently. We examined postmating, prezygotic reproductive isolation in three hybridizations within the Drosophila simulans species complex. We allowed females to mate only once, observed and timed all copulations, dissected a subset of the females to track the storage and retention of sperm, examined the number and hatchability of eggs laid after insemination, counted all progeny produced, and measured the longevity of mated females. Each of the three hybridizations is characterized by a different set of cryptic barriers to heterospecific fertilization. When D. simulans females mate with D. sechellia males, few heterospecific sperm are transferred, even during long copulations. In contrast, copulations of D. simulans females with D. mauritiana males are often too short to allow sperm transfer. Those that are long enough to allow insemination, however, involve the transfer of many sperm, but only a fraction of these heterospecific sperm are stored by females, who also lay fewer eggs than do D. simulans females mated with conspecific males. Finally, when D. mauritiana females mate with D. simulans males, sperm are transferred and stored in abundance, but are lost rapidly from the reproductive tract and are therefore used inefficiently. These results add considerably to the list of reproductive isolating mechanisms in this well-studied clade and possibly to the list of evolutionary processes that could contribute to their reproductive isolation.
在交配后但受精前起作用的生殖隔离形式可能是物种形成的重要组成部分，但很少被研究。我们研究了拟暗果蝇物种复合体中三个杂交组合的交配后、合子前生殖隔离。我们让雌蝇只交配一次，观察并记录所有交配的时间，解剖一部分雌蝇以追踪精子的储存和留存情况，检查授精后产下的卵的数量和孵化率，统计所有产生的后代数量，并测量已交配雌蝇的寿命。这三个杂交组合中的每一个都具有一组不同的对异种受精的隐性障碍。当拟暗果蝇雌蝇与塞舌尔果蝇雄蝇交配时，即使在长时间交配过程中，转移的异种精子也很少。相比之下，拟暗果蝇雌蝇与毛里求斯果蝇雄蝇的交配往往太短，无法进行精子转移。然而，那些长到足以进行授精的交配，会转移许多精子，但雌蝇只储存了这些异种精子的一部分，而且与同种雄蝇交配的拟暗果蝇雌蝇相比，它们产下的卵也更少。最后，当毛里求斯果蝇雌蝇与拟暗果蝇雄蝇交配时，精子会大量转移并储存，但会迅速从生殖道中流失，因此利用效率低下。这些结果大大增加了这个经过充分研究的进化枝中的生殖隔离机制清单，也可能增加了可能导致其生殖隔离的进化过程清单。
