ABSTRACT: Climate change plays a large role in driving species range shifts; however, the physical characteristics of an environment can also influence and alter species distributions. In New England salt marshes, the mud fiddler crab Minuca pugnax is expanding its range north of Cape Cod, MA, into the Gulf of Maine (GoM) due to warming waters. The burrowing lifestyle of M. pugnax means sediment compaction in salt marshes may influence the ability of crabs to dig, with more compact soils being resistant to burrowing. Previous studies indicate that salt marshes along the GoM have a higher sediment compaction relative to marshes south of Cape Cod. Physical characteristics of this habitat may be influencing the burrowing performance of M. pugnax and therefore the continuation of their northward range expansion into the GoM. We conducted a controlled laboratory experiment to determine if compaction affects the burrowing activity of M. pugnax in historical and range-expanded populations. We manipulated sediment compaction in standardized lab assays and measured crab burrowing performance with individuals collected from Nantucket (NAN, i.e. historical range) and the Plum Island Estuary (PIE, i.e. expanded range). We determined compaction negatively affected burrowing ability in crabs from both sites; however, crabs from PIE have a higher probability of burrowing in higher sediment compactions than NAN crabs. In addition, PIE crabs were more likely to burrow overall. We conclude that site level differences in compaction are likely altering burrowing behavior in the crab’s expanded-range territory by way of local adaptation or phenotypic plasticity.

中文翻译：

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沉积物选择：范围扩大的招潮蟹比其历史范围内的同类更适合挖洞

摘要：气候变化在推动物种范围变化方面发挥着重要作用；然而，环境的物理特征也会影响和改变物种分布。在新英格兰盐沼，由于海水变暖，泥提琴蟹Minuca pugnax正在将其活动范围从马萨诸塞州科德角以北扩大到缅因湾 (GoM)。M. pugnax的穴居生活方式意味着盐沼中的沉积物压实可能会影响螃蟹的挖掘能力，更紧密的土壤对穴居具有抵抗力。先前的研究表明，相对于科德角以南的沼泽，沿着 GoM 的盐沼具有更高的沉积物压实度。该栖息地的物理特征可能会影响M. pugnax的穴居性能因此，他们继续向北扩展到 GoM。我们进行了一项受控实验室实验，以确定压实是否会影响M. pugnax的挖洞活动在历史和范围扩大的人群中。我们在标准化实验室测定中操纵沉积物压实，并测量了从楠塔基特（NAN，即历史范围）和梅岛河口（PIE，即扩大范围）收集的个体的螃蟹穴居性能。我们确定压实对两个地点的螃蟹的挖洞能力都有负面影响；然而，来自 PIE 的螃蟹比 NAN 螃蟹有更高的可能性在更高的沉积物压实中挖洞。此外，PIE 蟹总体上更容易挖洞。我们得出结论，压实的现场水平差异可能会通过局部适应或表型可塑性改变螃蟹扩展范围内的挖洞行为。