ECOEVO Lab, Escola de Enxeñaría Forestal, Universidade de Vigo, Campus Universitario, 36005, Pontevedra, Galiza, Spain.
Sci Rep. 2017 Aug 10;7(1):7844. doi: 10.1038/s41598-017-08390-3.
In Calopteryx damselflies, males remove rivals' sperm stored by the female, thereby reducing sperm competition. This behaviour may create a sexual conflict, because females could lose the sperm stored in the spermatheca, used for long-term storage. Comparative evidence suggested antagonistic coevolution between sexes, which might prompt the evolution of narrow spermathecal ducts, or longer spermathecae, hindering sperm removal. Calopteryx haemorrhoidalis and C. splendens coexist and sometimes hybridize. Therefore, here I predicted that if females coevolve with conspecific males, heterospecific males should have an advantage when interspecific matings occur because females will show less resistance to them than to conspecific males. By hand-pairing females to males of both species, I found that in intraspecific and interspecific matings, sperm was almost completely removed from the bursa (97-100%), but only partially from the spermathecae, with more spermathecal removal in interspecific (63-71%) than intraspecific matings (14-33%). This suggests that heterospecific males are more efficient in sperm removal as predicted by a sexually-antagonistic coevolutionary scenario. Furthermore, in most cases, only the left spermatheca was emptied, suggesting that the evolution of more than one spermatheca might also be a female counter-adaptation to regain control over fertilization.
在豆娘目中，雄性会移除雌性体内由其他雄性储存的精子，从而减少精子竞争。这种行为可能会引发性冲突，因为雌性可能会失去储存在储精囊中用于长期储存的精子。比较证据表明，雌雄双方存在拮抗协同进化，这可能促使狭窄的储精管或更长的储精囊进化，从而阻碍精子的移除。豆娘 haemorrhoidalis 和 C. splendens 共存且有时杂交。因此，我预测如果雌性与同种雄性共同进化，当发生种间交配时，异配性雄性应该具有优势，因为雌性对它们的抵抗力比对同种雄性的抵抗力小。通过手动将雌性与两种雄性配对，我发现在种内和种间交配中，精子几乎完全从囊中被移除（97-100%），但只从储精囊中部分被移除，种间交配（63-71%）中比种内交配（14-33%）中更多地移除了储精囊中的精子。这表明，正如性拮抗协同进化情景所预测的那样，异配性雄性在精子移除方面更有效率。此外，在大多数情况下，只有左侧储精囊被排空，这表明超过一个储精囊的进化也可能是雌性为重新获得对受精的控制而做出的一种反适应。
