Drury J P, Grether G F
Department of Ecology and Evolutionary Biology, University of California, 612 Charles E. Young Dr. S., Los Angeles, CA 90095, USA
Proc Biol Sci. 2014 Dec 7;281(1796):20141737. doi: 10.1098/rspb.2014.1737.
Traits that mediate intraspecific social interactions may overlap in closely related sympatric species, resulting in costly between-species interactions. Such interactions have principally interested investigators studying the evolution of reproductive isolation via reproductive character displacement (RCD) or reinforcement, yet in addition to reproductive interference, interspecific trait overlap can lead to costly between-species aggression. Previous research on rubyspot damselflies (Hetaerina spp.) demonstrated that sympatric shifts in male wing colour patterns and competitor recognition reduce interspecific aggression, supporting the hypothesis that agonistic character displacement (ACD) drove trait shifts. However, a recent theoretical model shows that RCD overshadows ACD if the same male trait is used for both female mate recognition and male competitor recognition. To determine whether female mate recognition is based on male wing coloration in Hetaerina, we conducted a phenotype manipulation experiment. Compared to control males, male H. americana with wings manipulated to resemble a sympatric congener (H. titia) suffered no reduction in mating success. Thus, female mate recognition is not based on species differences in male wing coloration. Experimental males did, however, experience higher interspecific fighting rates and reduced survival compared to controls. These results greatly strengthen the case for ACD and highlight the mechanistic distinction between ACD and RCD.
介导种内社会互动的性状可能在亲缘关系密切的同域物种中重叠，从而导致代价高昂的种间互动。这类互动主要引起了研究人员的兴趣，他们通过生殖性状替换（RCD）或强化作用来研究生殖隔离的进化，然而，除了生殖干扰外，种间性状重叠还可能导致代价高昂的种间攻击行为。此前对红宝石豆娘（Hetaerina spp.）的研究表明，雄性翅膀颜色模式的同域变化以及竞争对手识别能力的变化会减少种间攻击行为，这支持了一种假说，即争斗性状替换（ACD）推动了性状变化。然而，最近的一个理论模型表明，如果同一雄性性状用于雌性配偶识别和雄性竞争对手识别，那么RCD会掩盖ACD。为了确定在Hetaerina中雌性配偶识别是否基于雄性翅膀颜色，我们进行了一项表型操纵实验。与对照雄性相比，翅膀被操纵得类似于同域近缘种（H. titia）的美洲H. americana雄性在交配成功率上没有降低。因此，雌性配偶识别并非基于雄性翅膀颜色的物种差异。然而，与对照相比，实验雄性确实经历了更高的种间战斗率且存活率降低。这些结果大大加强了支持ACD的论据，并突出了ACD和RCD之间的机制差异。
