Meik Jesse M, Watson Jessica A, Schield Drew R, Perry Blair W, Francioli Yannick, Guss Hannah, Mackessy Stephen P, Castoe Todd A
Department of Biological Sciences, Tarleton State University, Stephenville, TX, USA.
Department of Ocean Engineering and Marine Sciences, Florida Institute of Technology, Melbourne, FL, USA.
R Soc Open Sci. 2024 Aug 7;11(8):240345. doi: 10.1098/rsos.240345. eCollection 2024 Aug.
Both the metabolic theory of ecology and dynamic energy budget theory predict that climate influences body size through its effects on first-order determinants of energetics: reactive temperatures, carbon resources and oxygen availability. Although oxygen is seldom limiting in terrestrial systems, temperature and resources vary spatially. We used redundancy analyses and variation partitioning to evaluate the influence of climatic temperature, precipitation and their seasonalities on multivariate body size across the distributions of four species of the western rattlesnake group in North America (, , and ). Most species showed a pattern of increased body size in cooler, mesic climates and decreased body size in warmer, xeric climates. Exceptions to the pattern provided additional context through climatic idiosyncrasies in the distributions of each species. For example, the general pattern of a negative influence of temperature on body size was not apparent for , which ranges across the mildest climates overall among the four species. In contrast to previous studies, we found that seasonality had negligible effects on body size. We suggest that precipitation gradients correlate positively with resource availability in driving intraspecific body size and that temperature compounds this gradient by increasing baseline metabolic demands and restricting activity in particularly warm or otherwise extreme climates.
生态代谢理论和动态能量平衡理论均预测，气候通过对能量学一级决定因素（反应温度、碳资源和氧气可利用性）的影响来影响体型大小。尽管在陆地系统中氧气很少成为限制因素，但温度和资源在空间上存在差异。我们使用冗余分析和变异分解来评估气候温度、降水量及其季节性对北美西部响尾蛇属四种物种（、、和）分布范围内多变量体型大小的影响。大多数物种呈现出在较凉爽、湿润的气候中体型增大，而在较温暖、干旱的气候中体型减小的模式。该模式的例外情况通过每个物种分布中的气候特性提供了更多背景信息。例如，温度对体型大小的负面影响这一普遍模式在中并不明显，在这四个物种中，它总体分布在最温和的气候区域。与先前的研究不同，我们发现季节性对体型大小的影响可忽略不计。我们认为，在驱动种内体型大小方面，降水梯度与资源可利用性呈正相关，并且温度通过增加基础代谢需求以及在特别温暖或其他极端气候条件下限制活动，加剧了这种梯度变化。
