School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA.
Cornell Lab of Ornithology, Cornell University, Ithaca, New York, USA.
Ecol Lett. 2024 Aug;27(8):e14487. doi: 10.1111/ele.14487.
The hypothesis that species' ranges are limited by interspecific competition has motivated decades of debate, but a general answer remains elusive. Here we test this hypothesis for lowland tropical birds by examining species' precipitation niche breadths. We focus on precipitation because it-not temperature-is the dominant climate variable that shapes the biota of the lowland tropics. We used 3.6 million fine-scale citizen science records from eBird to measure species' precipitation niche breadths in 19 different regions across the globe. Consistent with the predictions of the interspecific competition hypothesis, multiple lines of evidence show that species have narrower precipitation niches in regions with more species. This means species inhabit more specialized precipitation niches in species-rich regions. We predict this niche specialization should make tropical species in high diversity regions disproportionately vulnerable to changes in precipitation regimes; preliminary empirical evidence is consistent with this prediction.
物种分布范围受种间竞争限制的假设激发了数十年来的争论，但仍未得出明确的答案。在这里，我们通过研究低地热带鸟类的降水生态位宽度来检验这一假说。我们之所以关注降水，是因为它（而非温度）是塑造低地热带生物群的主导气候变量。我们使用了 eBird 上的 360 万条精细尺度的公民科学记录，来衡量全球 19 个不同地区的物种降水生态位宽度。与种间竞争假说的预测一致，多种证据表明，在物种丰富度较高的地区，物种的降水生态位较窄。这意味着物种在物种丰富的地区栖息在更加专门化的降水生态位中。我们预测这种生态位特化会使高多样性地区的热带物种特别容易受到降水格局变化的影响；初步的实证证据与这一预测一致。
