Dias Tiffany, Lemoine Nathan P, Yanco Scott W, Zimova Marketa, Bay Rachel A, Weeks Brian C
School for Environment and Sustainability, University of Michigan, 440 Church Street, Ann Arbor, MI 48109, USA.
Department of Biological Sciences, Marquette University, 1428 West Clybourn Street, Milwaukee, WI 53233, USA.
Proc Biol Sci. 2025 Jan;292(2039):20242556. doi: 10.1098/rspb.2024.2556. Epub 2025 Jan 22.
Recent widespread reductions in body size across species have been linked to increasing temperatures; simultaneous increases in wing length relative to body size have been broadly observed but remain unexplained. Size and shape may change independently of one another, or these morphological shifts may be linked, with body size mediating or directly driving the degree to which shape changes. Using hierarchical Bayesian models and a morphological time series of 27 366 specimens from five North American migratory passerine bird species, we tested the roles that climate and body size have played in shifting wing length allometry over four decades. We found that colder temperatures and reduced precipitation during the first year of life were associated with increases in wing length relative to body size but did not explain long-term increases in wing length. We found no conclusive evidence that the slope of the relationship between body size and wing length changed among adult birds in response to any climatic variable or through time, suggesting that body size does not mediate shifts in relative wing length. Together, these findings suggest that long-term increases in wing length are not a compensatory adaptation mediated by size reductions, but rather are driven by non-climatic factors.
近期，物种间普遍出现的体型减小与气温升高有关；同时，相对于体型的翅长增加也被广泛观察到，但原因尚不明晰。体型和形状可能彼此独立变化，或者这些形态变化存在关联，体型可能介导或直接推动形状变化的程度。利用分层贝叶斯模型以及来自五种北美迁徙鸣禽的27366个标本的形态时间序列，我们测试了气候和体型在过去四十年中对翅长异速生长变化所起的作用。我们发现，生命第一年温度较低和降水量减少与相对于体型的翅长增加有关，但无法解释翅长的长期增长。我们没有找到确凿证据表明成年鸟类中体型与翅长之间关系的斜率会因任何气候变量或随时间而改变，这表明体型并不会介导相对翅长的变化。总之，这些发现表明翅长的长期增加并非由体型减小介导的补偿性适应，而是由非气候因素驱动的。
