Queen execution, diploid males, and selection for and against polyandry in the Brazilian stingless bee Scaptotrigona depilis

Female mating frequency varies. Determining the causes of this variation is an active research area. We tested the hypothesis that in stingless bees, Meliponini, single mating is due to the execution of queens that make a matched mating at the CSD (complementary sex determination) locus and have diploid male offspring. We studied the Brazilian species Scaptotrigona depilis. We made up 70 test colonies so that 50% (single matched mating), 25% (double mating), 12.5% (4-mating), or 0% (single non-matched mating) emerging brood were diploid males. Queen execution following diploid male emergence was equal and high in colonies producing 50% (77% executed) and 25% (75%) diploid males, versus equal and low in colonies producing 12.5% (7%) and 0% (0%) diploid males. These results show that queens that mate with two males with similar paternity suffer an increased chance of being executed, which selects against double mating. However, double mating with unequal paternity (e.g.,
25:75), which oc...

雌性蜂后的交配频率存在个体差异，探究该差异的成因是当前的活跃研究领域。我们针对无刺蜂（stingless bees）麦蜂族（Meliponini）验证了一项假说：单次交配的演化成因，源于那些在互补性别决定位点（complementary sex determination, CSD）上发生匹配性交配、并产生二倍体雄性子代的蜂后会被处决。我们以巴西本土物种斯氏无刺蜂（Scaptotrigona depilis）为研究对象，构建了70个试验蜂群，使各组羽化子代中二倍体雄性的占比分别为50%（单次匹配交配）、25%（两次交配）、12.5%（四次交配）以及0%（单次非匹配交配）。二倍体雄性羽化后，蜂后被处决的比例在产生50%二倍体雄性的蜂群（77%被处决）与产生25%二倍体雄性的蜂群（75%）中均处于较高且相近的水平；而在产生12.5%二倍体雄性的蜂群（7%）与产生0%二倍体雄性的蜂群（0%）中则处于较低且相近的水平。上述结果表明，与两只父权比例相近的雄蜂交配的蜂后，其被处决的概率会显著升高，这会对两次交配行为产生负选择压力。然而，当两次交配的父权比例不均等（例如25:75）时，该情况……