Does past evolutionary history under different mating regimes influence the demographic dynamics of interspecific competition?

Interspecific interactions are contingent upon organism phenotypes, and thus phenotypic evolution can modify interspecific interactions and affect ecological dynamics. Recent studies have suggested that male-male competition within a species selects for capability to reproductively interfere with a closely related species. Here we examine the effect of past evolutionary history under different mating regimes on the demographic dynamics of interspecific competition in Callosobruchus seed beetles. We used previously established experimental evolution lines of C. chinensis that evolved under either forced lifelong monogamy or polygamy for 17 generations, and examined the demographic dynamics of competition between these C. chinensis lines and a congener, C. maculatus. Callosobruchus chinensis was competitively excluded by C. maculatus in all trials. Time series data analyses suggested that reproductive interference from C. chinensis was relatively more important in the trials involving polygamous C. chinensis than those involving monogamous C. chinensis, in accordance with the potentially higher reproductive interference capability of polygamous C. chinensis. However, the estimated signs and magnitudes of interspecific interactions were not fully consistent with this explanation, implying the evolution of not only reproductive interference but also other interaction mechanisms. Our study thus suggests multifaceted effects of sexually-selected traits on interspecific competitive dynamics.

种间相互作用（interspecific interactions）依赖于生物表型（organism phenotypes），因此表型进化（phenotypic evolution）可改变种间相互作用并影响生态动力学（ecological dynamics）。近期研究指出，物种种内雄性间竞争（male-male competition）会筛选出可与近缘物种产生生殖干扰（reproductive interference）的能力。本研究以豆象属种子甲虫（Callosobruchus）为研究体系，探究不同交配制度（mating regimes）下的过往进化历史对种间竞争种群动态（demographic dynamics）的影响。我们使用此前已建立的绿豆象（Callosobruchus chinensis）实验进化品系，该品系分别在强制终身单配偶制或多配偶制条件下进化了17代，并检测了这些绿豆象品系与其近缘同属物种四纹豆象（Callosobruchus maculatus）之间的竞争种群动态。所有试验中，四纹豆象均将绿豆象竞争性排除。时间序列数据分析显示，相较于使用经单配偶制进化的绿豆象品系的试验组，使用经多配偶制进化的绿豆象品系的试验组中，绿豆象产生的生殖干扰作用相对更强，这与多配偶制绿豆象可能具备更高生殖干扰能力的推测相符。然而，种间相互作用的估计参数符号与强度并未完全契合这一解释，这暗示除生殖干扰外，还存在其他相互作用机制的进化。综上，本研究表明性选择性状（sexually-selected traits）对种间竞争动力学具有多维度影响。