Fjerdingstad Else J, Gertsch Pia J, Keller Laurent
Department of Zoology and Animal Ecology, Institute of Ecology, University of Lausanne, Switzerland.
Evolution. 2002 Mar;56(3):553-62. doi: 10.1111/j.0014-3820.2002.tb01366.x.
Although multiple mating most likely increases mortality risk for social insect queens and lowers the kin benefits for nonreproductive workers, a significant proportion of hymenopteran queens mate with several males. It has been suggested that queens may mate multiply as a means to manipulate sex ratios to their advantage. Multiple paternity reduces the extreme relatedness value of females for workers, selecting for workers to invest more in males. In populations with female-biased sex ratios, queens heading such male-producing colonies would achieve a higher fitness. We tested this hypothesis in a Swiss and a Swedish population of the ant Lasius niger. There was substantial and consistent variation in queen mating frequency and colony sex allocation within and among populations, but no evidence that workers regulated sex allocation in response to queen mating frequency; the investment in females did not differ among paternity classes. Moreover, population-mean sex ratios were consistently less female biased than expected under worker control and were close to the queen optimum. Queens therefore had no incentive to manipulate sex ratios because their fitness did not depend on the sex ratio of their colony. Thus, we found no evidence that the sex-ratio manipulation theory can explain the evolution and maintenance of multiple mating in L. niger.
虽然多次交配极有可能增加社会性昆虫蚁后的死亡风险，并降低无生殖能力的工蚁的亲缘利益，但相当一部分膜翅目蚁后会与几只雄蚁交配。有人提出，蚁后可能通过多次交配来操纵性别比例，使其对自己有利。多重父权降低了工蚁所育雌性的极高亲缘关系值，促使工蚁对雄性投入更多。在雌性偏向的性别比例群体中，领导此类产雄群体的蚁后将获得更高的适合度。我们在瑞士和瑞典的黑褐蚁种群中检验了这一假设。种群内部和种群之间，蚁后的交配频率和群体性别分配存在显著且一致的差异，但没有证据表明工蚁会根据蚁后的交配频率来调节性别分配；不同父权类别的雌性投入并无差异。此外，种群平均性别比例始终不像在工蚁控制下预期的那样偏向雌性，且接近蚁后的最优比例。因此，蚁后没有动机去操纵性别比例，因为它们的适合度并不取决于其群体的性别比例。所以，我们没有发现证据表明性别比例操纵理论能够解释黑褐蚁多次交配的进化与维持。
