Dajčman Urban, Enriquez-Urzelai Urtzi, Žagar Anamarija
Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia.
Department of Organisms and Ecosystems Research, National Institute of Biology, Ljubljana, Slovenia.
J Anim Ecol. 2025 May;94(5):999-1013. doi: 10.1111/1365-2656.70030. Epub 2025 Mar 20.
Understanding differences in life-history outcomes under variable abiotic conditions is essential for understanding species coexistence. At middle elevations, a mosaic of available sets of abiotic conditions could allow highland and lowland species of the same ecological guild to overlap. Therefore, these sites are excellent to study the influence of abiotic conditions on life history and, thus, spatial overlap patterns of competing species. To test differences in life-history outcomes, we selected a pair of closely related lacertids, Iberolacerta horvathi and Podarcis muralis, with an overlapping geographical range but a contrasting elevational distribution. To assess how abiotic and biotic factors contribute to the realized niches of both species, we first built dynamic energy budget (DEB) models for each species based on available functional and life-history data. Then, we used a mechanistic modelling framework (NicheMapR) to simulate the microclimatic conditions at 15 study sites across an elevational gradient and performed whole life-cycle simulations for both species to compare egg development times, lifespans, reproductive years, mean yearly basking and foraging times and yearly fecundity in syntopy and allotopy along the elevational gradient. Our simulations show that the variability of abiotic conditions along an elevational gradient affects life-history traits of both species. We found strong effects of species and elevation on life-history outcomes such as longevity, activity and fecundity. We also observed the effects of syntopy/allotopy on egg development times, activity and reproductive output. In addition, we found a significant interplay between elevation and species impacting fecundity where occupying higher elevation habitats resulted in a more pronounced reduction in fecundity in P. muralis. Furthermore, using two different thermal preferences for spring and summer, we show that some physiological and reproductive traits change with seasonal changes in thermal preferences. Based on our simulations, we conclude that the intermediate elevations that harbour the majority of syntopic populations exhibit high environmental variability that is likely facilitating species coexistence. Since our model predictions support that the current elevational distribution of the species is not only affected by abiotic factors, this suggests that past historical contingencies might have also played a significant role. Our study provides a framework using mechanistic models to understand current distribution patterns of two interacting species by comparing life-history differences between species based on responses to changing abiotic conditions along an elevation gradient.
了解在可变非生物条件下生活史结果的差异对于理解物种共存至关重要。在中等海拔地区，一系列可用的非生物条件组合可能使同一生态类群的高地和低地物种出现重叠。因此，这些地点非常适合研究非生物条件对生活史的影响，进而研究竞争物种的空间重叠模式。为了测试生活史结果的差异，我们选择了一对亲缘关系密切的蜥蜴，即霍氏伊比利亚蜥（Iberolacerta horvathi）和岩蜥（Podarcis muralis），它们地理分布范围重叠，但海拔分布相反。为了评估非生物和生物因素如何影响这两个物种的实际生态位，我们首先根据现有的功能和生活史数据为每个物种建立了动态能量预算（DEB）模型。然后，我们使用一个机理建模框架（NicheMapR）来模拟沿海拔梯度的15个研究地点的微气候条件，并对这两个物种进行全生命周期模拟，以比较沿海拔梯度在同域和异域情况下的卵发育时间、寿命、繁殖年限、年平均晒太阳和觅食时间以及年繁殖力。我们的模拟表明，沿海拔梯度的非生物条件变异性会影响这两个物种的生活史特征。我们发现物种和海拔对寿命、活动和繁殖力等生活史结果有强烈影响。我们还观察到同域/异域对卵发育时间、活动和繁殖输出的影响。此外，我们发现海拔和物种之间存在显著的相互作用，影响繁殖力，其中占据较高海拔栖息地会导致岩蜥的繁殖力更明显下降。此外，利用春季和夏季两种不同的热偏好，我们表明一些生理和繁殖特征会随着热偏好的季节性变化而改变。基于我们的模拟，我们得出结论，容纳大多数同域种群的中等海拔地区表现出高环境变异性，这可能促进了物种共存。由于我们的模型预测支持物种当前的海拔分布不仅受非生物因素影响，这表明过去的历史偶然性可能也起到了重要作用。我们的研究提供了一个框架，通过基于沿海拔梯度对变化的非生物条件的响应比较物种间的生活史差异，使用机理模型来理解两个相互作用物种的当前分布模式。
