Davis Jeremy M, Coogan Laura E, Papaj Daniel R
Department of Biology, Vassar College, Poughkeepsie, NY, USA,
Oecologia. 2015 Sep;179(1):55-62. doi: 10.1007/s00442-015-3314-6. Epub 2015 Apr 21.
The ability of individual animals to select habitats optimal for development and survival can be constrained by the costs of moving through the environment. Animals that seek overwintering sites underground, for example, may be constrained by the energy required to burrow into the soil. We conducted field and laboratory studies to determine the relationship between individual size and overwintering site selection in the tephritid flies, Rhagoletis juglandis and Rhagoletis suavis. We also explored the effect of site selection on pupal mortality, parasitism, and the ability to emerge from overwintering sites after eclosion. In both species, and in both lab and field tests, larger pupae were found at deeper soil depths. In addition, marginally non-significant trends indicated pupae in deeper sites were 48% more likely to survive the overwintering period. Finally, larger individuals were more likely to eclose and emerge from the soil at a given depth, but flies in deep overwintering sites were less likely to emerge from those sites than flies in shallow sites. Our data indicate that overwintering site selection represents a trade-off between avoiding predators and parasites that occur at shallow sites, and the energetic and mortality costs of burrowing to, overwintering in, and emerging from, deeper sites. The size-dependent overwintering site selection demonstrated here has implications for population dynamics and pest control strategies. Some fly control measures, such as the introduction of parasites or predators, will be mitigated when the deepest and least accessible overwintering pupae represent a disproportionately large amount of the population's reproductive capacity.
个体动物选择最适合发育和生存的栖息地的能力可能会受到在环境中移动的成本的限制。例如，在地下寻找越冬地点的动物可能会受到挖掘土壤所需能量的限制。我们进行了野外和实验室研究，以确定胡桃实蝇（Rhagoletis juglandis）和温和实蝇（Rhagoletis suavis）个体大小与越冬地点选择之间的关系。我们还探讨了地点选择对蛹死亡率、寄生率以及羽化后从越冬地点羽化出来的能力的影响。在这两个物种中，以及在实验室和野外试验中，都发现较大的蛹位于更深的土壤深度。此外，略微不显著的趋势表明，位于较深地点的蛹越冬期存活的可能性要高48%。最后，较大的个体在给定深度更有可能羽化并从土壤中出来，但在深层越冬地点的苍蝇比在浅层地点的苍蝇更不容易从那些地点羽化出来。我们的数据表明，越冬地点选择代表了在避免浅层地点出现的捕食者和寄生虫与挖掘到更深地点、在更深地点越冬以及从更深地点羽化出来的能量和死亡率成本之间的权衡。这里展示的与大小相关的越冬地点选择对种群动态和害虫控制策略具有影响。当最深且最难进入的越冬蛹占种群繁殖能力的比例过大时，一些苍蝇控制措施，如引入寄生虫或捕食者，将会受到影响。
