Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, Toulouse, France.
Innovations thérapeutiques et résistances, Ecole Nationale Vétérinaire de Toulouse, INRA, Toulouse, France.
PLoS Biol. 2019 Jul 2;17(7):e3000319. doi: 10.1371/journal.pbio.3000319. eCollection 2019 Jul.
From invertebrates to vertebrates, a wealth of species display transient sociality during their life cycle. Investigating the causes of dispersal in temporary associations is important to better understand population dynamics. It is also essential to identify possible mechanisms involved in the evolutionary transition from transient to stable sociality, which has been documented repeatedly across taxa and typically requires the suppression of dispersal. In many animals, the onset of dispersal during ontogeny coincides with a sharp decline in social tolerance, but the causal relationship still remains poorly understood. Spiders offer relevant models to explore this question, because the adults of the vast majority of species (>48,000) are solitary and aggressive, but juveniles of most (if not all) species are gregarious and display amicable behaviors. We deployed a combination of behavioral, chemical, and modelling approaches in spiderlings of a solitary species to investigate the mechanisms controlling the developmental switch leading to the decline of social cohesion and the loss of tolerance. We show that maturation causes an increase in mobility that is sufficient to elicit dispersal without requiring any change in social behaviors. Our results further demonstrate that social isolation following dispersal triggers aggressiveness in altering the processing of conspecifics' cues. We thus provide strong evidence that aggression is a consequence, not a cause, of dispersal in spiderlings. Overall, this study highlights the need of extended social interactions to preserve tolerance, which opens new perspectives for understanding the routes to permanent sociality.
从无脊椎动物到脊椎动物，许多物种在其生命周期中都会表现出短暂的社会性。研究暂时性群体中扩散的原因对于更好地了解种群动态非常重要。此外，确定从短暂到稳定的社会性进化转变中涉及的可能机制也很重要，这种转变已在多个分类群中得到反复记录，通常需要抑制扩散。在许多动物中，个体发育过程中扩散的开始与社会容忍度的急剧下降同时发生，但因果关系仍知之甚少。蜘蛛提供了相关的模型来探索这个问题，因为绝大多数物种（>48,000 种）的成年蜘蛛都是独居和具有攻击性的，但大多数（如果不是全部）物种的幼蛛都是群居的，并且表现出友好的行为。我们在独居物种的蜘蛛幼蛛中采用了行为、化学和建模方法的组合，以研究控制导致社会凝聚力下降和容忍度丧失的发育开关的机制。我们表明，成熟会导致移动性增加，足以引发扩散，而无需改变任何社会行为。我们的研究结果进一步表明，在扩散后进行社会隔离会引发攻击性，从而改变对同种个体线索的处理。因此，我们提供了强有力的证据表明，攻击性是扩散的结果，而不是原因。总的来说，这项研究强调了需要扩展社会互动来维持容忍度，这为理解永久性社会性的途径开辟了新的视角。
