While much attention has been paid to the climatic controls of species' range limits, other factors such as dispersal limitation are also important. Temperature is an important control of the distribution of coastal mangrove forests, and mangrove expansion at multiple poleward range limits has been linked to increasing temperatures. However, mangrove abundances at other poleward range limits have been surprisingly insensitive to climate change, indicating other drivers of range limitation. For example, along the west coast of North America, the poleward mangrove range limits are found on the Baja California and mainland coasts of Mexico, between 26°48ʹ and 30°18ʹN. Non-climatic factors may play an important role in setting these range limits as 1) the abundance of range limit populations has been relatively insensitive to climate variability and 2) an introduced population of mangroves has persisted hundreds of kilometers north of the natural range limits. We combined a species distribution model with a high-resolution oceanographic transport model to identify the roles of climate and dispersal limitation in controlling mangrove distributions. We identified estuarine habitat that is likely climatically suitable for mangroves north of the current range limits. However, propagules from current mangrove populations are unlikely to reach these suitable locations due to prevailing ocean currents and geomorphic factors that create a patchy distribution of estuarine habitat with large between-patch distances. Thus, although climate change is driving range shifts of mangroves in multiple regions around the world, dispersal is currently limiting poleward mangrove expansion at several range limits, including the west coast of North America.

中文翻译：

---

扩散限制了北美西海岸红树林向极地扩张


虽然人们已经非常关注物种分布范围限制的气候控制，但其他因素（如扩散限制）也很重要。温度是控制沿海红树林分布的重要因素，红树林在多个极地范围限制下的扩张与温度升高有关。然而，其他极地分布范围限制的红树林丰度对气候变化出人意料地不敏感，这表明了范围限制的其他驱动因素。例如，在北美洲西海岸，下加利福尼亚和墨西哥大陆海岸的北纬 26°48ʹ 至 30°18ʹ 之间，红树林的极地分布范围限制。非气候因素可能在设定这些范围限制方面发挥重要作用，因为 1） 范围限制种群的丰富性对气候变化相对不敏感，以及 2） 引入的红树林种群在自然范围限制以北数百公里处持续存在。我们将物种分布模型与高分辨率海洋学传输模型相结合，以确定气候和扩散限制在控制红树林分布中的作用。我们确定了在气候上可能适合当前范围限制以北的红树林的河口栖息地。然而，由于盛行的洋流和地貌因素造成了河口栖息地的斑驳分布，斑块间距离较大，因此当前红树林种群的繁殖体不太可能到达这些合适的位置。因此，尽管气候变化正在推动全球多个地区红树林的范围变化，但扩散目前正在限制了包括北美西海岸在内的几个范围限制了红树林向极地扩张。