Allen Bengt J, Levinton Jeffrey S
Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY, 11794-5245, USA,
Oecologia. 2014 Sep;176(1):25-34. doi: 10.1007/s00442-014-3002-y. Epub 2014 Jul 6.
In mid-Atlantic salt marshes, reproductively active male sand fiddler crabs, Uca pugilator, use a single greatly enlarged major claw as both a weapon to defend specialized breeding burrows from other males and an ornament to attract females for mating. During the summer breeding season, females strongly prefer to mate with males controlling burrows in open areas high on the shore. Food availability decreases while temperature and desiccation stress increase with increasing shore height, suggesting that the timing and location of fiddler crab mating activity may result in a potential trade-off between reproductive success and physiological condition for male crabs. We compared thermal preferences in laboratory choice experiments to body temperatures of models and living crabs in the field and found that from the perspective of a fiddler crab, the thermal environment of the mating area is quite harsh relative to other marsh microhabitats. High temperatures significantly constrained fiddler crab activity on the marsh surface, a disadvantage heightened by strongly reduced food availability in the breeding area. Nevertheless, when the chance of successfully acquiring a mate was high, males accepted a higher body temperature (and concomitantly higher metabolic and water loss rates) than when the chances of mating were low. Likewise, experimentally lowering costs by adding food and reducing thermal stress in situ increased fiddler crab waving display levels significantly. Our data suggest that fiddler crabs can mitigate potential life history trade-offs by tuning their behavior in response to the magnitude of both energetic and non-energetic costs and benefits.
在大西洋中部的盐沼中，处于繁殖活跃期的雄性沙滩招潮蟹（学名：Uca pugilator）会使用一只特别巨大的螯作为武器，来保卫专门的繁殖洞穴免受其他雄性的侵犯，同时也作为吸引雌性进行交配的装饰品。在夏季繁殖季节，雌性强烈倾向于与控制着岸边高处开阔区域洞穴的雄性交配。随着岸边高度增加，食物可获得性降低，而温度和干燥胁迫增加，这表明招潮蟹交配活动的时间和地点可能会导致雄性螃蟹在繁殖成功率和生理状况之间产生潜在的权衡。我们在实验室选择实验中比较了热偏好与模型以及野外活体螃蟹的体温，发现从招潮蟹的角度来看，交配区域的热环境相对于其他盐沼微生境而言相当恶劣。高温显著限制了招潮蟹在盐沼表面的活动，而繁殖区域食物可获得性的大幅降低加剧了这一不利因素。然而，当成功获得配偶的机会很高时，雄性会接受比交配机会低时更高的体温（以及随之而来更高的代谢率和水分流失率）。同样，通过在原地添加食物和降低热胁迫来实验性地降低成本，显著提高了招潮蟹挥舞展示的水平。我们的数据表明，招潮蟹可以通过根据能量和非能量成本与收益的大小调整其行为，来减轻潜在的生活史权衡。
