Department of Environmental Conservation, University of Massachusetts, 160 Holdsworth Hall, Amherst, MA, 01003, USA.
Department of Biology, Saint Mary's College, Notre Dame, IN, 46556, USA.
Glob Chang Biol. 2017 Apr;23(4):1390-1399. doi: 10.1111/gcb.13478. Epub 2016 Sep 21.
Shifts of distributions have been attributed to species tracking their fundamental climate niches through space. However, several studies have now demonstrated that niche tracking is imperfect, that species' climate niches may vary with population trends, and that geographic distributions may lag behind rapid climate change. These reports of imperfect niche tracking imply shifts in species' realized climate niches. We argue that quantifying climate niche shifts and analyzing them for a suite of species reveal general patterns of niche shifts and the factors affecting species' ability to track climate change. We analyzed changes in realized climate niche between 1984 and 2012 for 46 species of North American birds in relation to population trends in an effort to determine whether species differ in the ability to track climate change and whether differences in niche tracking are related to population trends. We found that increasingly abundant species tended to show greater levels of niche expansion (climate space occupied in 2012 but not in 1980) compared to declining species. Declining species had significantly greater niche unfilling (climate space occupied in 1980 but not in 2012) compared to increasing species due to an inability to colonize new sites beyond their range peripheries after climate had changed at sites of occurrence. Increasing species, conversely, were better able to colonize new sites and therefore showed very little niche unfilling. Our results indicate that species with increasing trends are better able to geographically track climate change compared to declining species, which exhibited lags relative to changes in climate. These findings have important implications for understanding past changes in distribution, as well as modeling dynamic species distributions in the face of climate change.
分布的转移归因于物种通过空间跟踪其基本气候小生境。然而，现在有几项研究表明，小生境跟踪并不完美，物种的气候小生境可能随种群趋势而变化，地理分布可能滞后于快速的气候变化。这些关于小生境跟踪不完善的报告意味着物种实际气候小生境的变化。我们认为，量化物种的气候小生境变化并对一系列物种进行分析，可以揭示小生境变化的一般模式以及影响物种跟踪气候变化能力的因素。我们分析了 1984 年至 2012 年间 46 种北美鸟类的实际气候小生境变化与种群趋势的关系，以确定物种在跟踪气候变化方面的能力是否存在差异，以及小生境跟踪的差异是否与种群趋势有关。我们发现，与衰退物种相比，越来越丰富的物种往往表现出更大程度的小生境扩张（2012 年而非 1980 年占据的气候空间）。与增长物种相比，衰退物种的小生境空缺（1980 年而非 2012 年占据的气候空间）明显更大，这是由于在发生气候变化后，它们无法在发生地的范围边缘以外的新地点殖民，而这些新地点已经发生了变化。相反，增长物种能够更好地殖民新地点，因此小生境空缺非常小。我们的研究结果表明，与衰退物种相比，具有增长趋势的物种在地理上更能跟踪气候变化，而衰退物种相对于气候变化存在滞后。这些发现对于理解过去的分布变化以及在气候变化面前模拟动态物种分布具有重要意义。
