Data from: Habitat saturation promotes delayed dispersal in a social reptile

When and where offspring disperse has important implications for the evolutionary emergence and maintenance of group living. In non-cooperative breeders, direct benefits of delayed dispersal are relatively limited, suggesting that decisions regarding whether or not to remain in the parental territory are largely driven by the availability of suitable habitat in which to settle. While there is ample evidence of correlations between habitat saturation and delayed dispersal, experimental tests are rare, particularly for species with facultative group formation. We manipulated the density of conspecifics in enclosed populations of a family living reptile to experimentally evaluate the influence of habitat saturation on the tendency to delay dispersal. Habitat saturation did not influence whether or not offspring explored their surroundings. However, when conspecific density was high, more offspring delayed dispersal and those that did settle in high-density enclosures had reduced survival. These patterns appear to be due to increased dispersal costs imposed by conspecific aggression; offspring that explored high-density enclosures had reduced body condition and a greater risk of mortality. We discuss these results in the context of the evolutionary origins of family living.

后代扩散的时机与位置，对群居生活的演化起源与维持具有重要意义。在非协作繁育类群中，延迟扩散的直接收益相对有限，这表明个体是否留在亲本领地的决策，主要由可获取的适宜定居生境的可用性所驱动。尽管已有大量证据表明生境饱和与延迟扩散之间存在关联，但相关实验验证仍较为匮乏，尤其是对于具有兼性群居特性的物种。我们以一种家族群居型爬行动物的封闭种群为研究对象，通过操控同种个体密度，实验性地评估生境饱和对后代延迟扩散倾向的影响。研究发现，生境饱和并未影响后代对周围环境的探索行为。然而，当同种个体密度较高时，更多后代选择延迟扩散；而在高密度围栏环境中定居的后代，其存活率显著降低。此类模式似乎源于同种个体间攻击行为所带来的扩散成本上升：在高密度围栏环境中进行探索的后代，其身体状况有所下降，死亡风险也显著升高。我们结合家族群居生活的演化起源这一研究背景，对本实验结果展开了讨论。