Alternative reproductive tactics (ARTs) often exhibit more than one mating behavior depending on social context (i.e., behavioral plasticity). It has been hypothesized that by constraining an ART from reaching optimal morphological states, intralocus tactical conflict could promote the maintenance of behavioral plasticity in ARTs, rather than the use of a fixed mating behavior to match an optimal morphological state. For selection on either behavior or morphology to influence one another, there would need to be genetic integration between these traits within the behaviorally plastic males. To examine this possibility, we compared the relationship between body shape, body size and propensity to use sneak-chase behavior across experienced wild-caught males and inexperienced lab reared males from the behaviorally plastic ART (sneaker males) of the swordtail fish Xiphophorus multilineatus. The smaller, more narrow-bodied sneaker males use both force copulatory sneak-chases and courtship behavior to access females, while the larger, deeper-bodied courter males are fixed in their use of courtship behavior. We detected similar relationships between body size and the propensity to use sneak-chase behavior within the sneaker males when they were alone with a female (no competitor present) for both experienced and inexperienced males, suggesting genetic integration between behavior and body size. Body shape, on the other hand, was more complex and suggested both genetic integration (more fusiform males from both groups were more likely to use sneak-chase), as well as learning depending on subtle differences in body shape. We discuss how intralocus tactical conflict on morphological traits that are genetically integrated with behaviors has the potential to maintain behavioral plasticity in the X. multilineatus sneaker males and influence the evolution of ARTs in general.

根据社会背景（即行为可塑性），替代生殖策略 (ARTs) 通常表现出不止一种交配行为。据推测，通过限制 ART 达到最佳形态状态，位点内战术冲突可以促进 ART 中行为可塑性的维持，而不是使用固定的交配行为来匹配最佳形态状态。为了对行为或形态的选择相互影响，需要在行为可塑性雄性内的这些特征之间进行遗传整合。为了检验这种可能性，我们比较了体型之间的关系，剑齿鱼。体型较小、体型较窄的运动鞋雄性使用强制交配偷猎和求爱行为来接近雌性，而体型较大、体型较深的求偶雄性则固定使用求偶行为。对于有经验和没有经验的男性，当他们与女性（没有竞争对手）单独在一起时，我们发现体型与运动鞋男性使用偷袭行为的倾向之间存在相似的关系，这表明行为与体型之间存在遗传整合。另一方面，体型更复杂，这表明遗传整合（来自两组的更多梭形雄性更有可能使用偷袭），以及根据体型的细微差异进行学习。X. multilineatus运动鞋男性并影响 ART 的总体发展。