Data from: Adaptive responses and disruptive effects: how major wildfire influences kinship-based social interactions in a forest marsupial

Environmental disturbance is predicted to play a key role in the evolution of animal social behaviour. This is because disturbance affects key factors underlying social systems, such as demography, resource availability and genetic structure. However, because natural disturbances are unpredictable there is little information on their effects on social behaviour in wild populations. Here, we investigated how a major wildfire affected cooperation (sharing of hollow trees) by a hollow-dependent marsupial. We based two alternative social predictions on the impacts of fire on population density, genetic structure and resources. We predicted an adaptive social response from previous work showing that kin selection in den-sharing develops as competition for den resources increases. Thus, kin selection should occur in burnt areas because the fire caused the loss of 80% of hollow-bearing trees, but no detectable mortality. Alternatively, fire may have a disruptive social effect, whereby post-fire home range-shifts ‘neutralise’ fine-scale genetic structure, thereby removing opportunities for kin selection between neighbours. Both predictions occurred: the disruptive social effect in burnt habitat and the adaptive social response in adjacent unburnt habitat. The latter followed a massive demographic influx to unburnt ‘refuge’ habitat that increased competition for dens, leading to a density-related kin selection response. Our results show remarkable short-term plasticity of animal social behaviour and demonstrate how the social effects of disturbance extend into undisturbed habitat due to landscape-scale demographic shifts. We predicted long-term changes in kinship-based cooperative behaviour resulting from the genetic and resource impacts of forecast changes to fire regimes in these forests.环境扰动（environmental disturbance）被认为在动物社会行为的演化中发挥关键作用。这是因为扰动会影响社会系统的核心影响因子，诸如种群统计学（demography）、资源可获得性（resource availability）以及遗传结构（genetic structure）。然而，由于自然扰动具有不可预测性，目前关于其对野生种群社会行为影响的研究资料十分有限。本研究针对一场大型野火如何影响依赖树洞的有袋类动物（hollow-dependent marsupial）的合作行为（树洞共享行为，sharing of hollow trees）展开了调查。我们基于野火对种群密度（population density）、遗传结构（genetic structure）以及资源的影响，提出了两种对立的社会行为预测假说。此前的研究表明，随着树洞资源竞争加剧，树洞共享行为中的亲缘选择（kin selection）效应会增强，据此我们预测会出现适应性的社会行为响应。因此，在过火区域应会出现亲缘选择（kin selection）现象——这场野火导致80%的含树洞林木（hollow-bearing trees）丧失，但未检测到动物个体死亡。另一种可能是，野火会产生破坏性的社会效应：火后个体家域（home range）转移会‘抵消’种群的精细尺度遗传结构（fine-scale genetic structure），从而消除邻居间进行亲缘选择（kin selection）的机会。两种预测均得到了验证：过火生境中出现了破坏性社会效应，而相邻未过火生境则呈现出适应性社会响应。后者的出现源于大量个体迁入未过火的‘避难所’生境（refuge habitat），加剧了树洞资源的竞争，进而引发了与种群密度相关的亲缘选择（kin selection）响应。本研究结果揭示了动物社会行为惊人的短期可塑性，并证实了由于景观尺度（landscape-scale）的种群动态变化，扰动带来的社会效应可延伸至未受扰动的生境中。我们还预测，由于这些森林的火灾态势（fire regimes）变化会对遗传结构与资源产生影响，基于亲缘关系的合作行为将出现长期变化。