Faculty of Biology, Conservation Ecology, Philipps-Universität Marburg, Karl-von-Frisch-Straße 8, Marburg, 35043, Germany.
Biodiversity and Climate Research Centre (BiK-F), Senckenberganlage 25, Frankfurt (Main), 60325, Germany.
Ecology. 2018 Sep;99(9):2090-2102. doi: 10.1002/ecy.2436. Epub 2018 Jul 26.
Morphological traits provide the interface between species and their environment. For example, body size affects the fitness of individuals in various ways. Yet especially for ectotherms, the applicability of general rules of interspecific clines of body size and even more so of other morphological traits is still under debate. Here we tested relationships between elevation (as a proxy for temperature) and productivity with four ecologically relevant morphological traits of orthopteran assemblages that are related to fecundity (body size), dispersal (wing length), jumping ability (hind femur length), and predator detection (eye size). We measured traits of 160 orthopteran species that were sampled along an extensive environmental gradient at Mt. Kilimanjaro (Tanzania), spanning elevations from 790 to 4,410 m above sea level (a.s.l.) with different levels of plant productivity. For traits other than body size, we calculated the residuals from a regression on body length to estimate the variation of traits irrespective of body size. Bayesian analyses revealed that mean body size of assemblages, as well as the means of relative wing length, hind femur length, and eye size, decreased with increasing elevation. Body size and relative eye size also decreased with increasing productivity. Both phylogenetic relationships, as well as species-specific adaptations, contributed to these patterns. Our results suggest that orthopteran assemblages had higher fecundity and better dispersal and escape abilities, as well as better predator detection at higher temperatures (low elevations) than at low temperatures (high elevations). Large body sizes might be advantageous in habitats with low productivity because of a reduced risk of starvation. Likewise, large eye size might be advantageous because of the ability to detect predators in habitats with low vegetation cover, where hiding possibilities are scarce. Our study highlights that changes in temperature and productivity not only lead to interspecific changes in body size but are also related to independent changes of other morphological traits that influence the ecological fit of organisms in their environment.
形态特征为物种与其环境之间提供了界面。例如，体型大小以各种方式影响个体的适应性。然而，特别是对于变温动物，种间体型渐变的一般规律的适用性，甚至其他形态特征的适用性，仍存在争议。在这里，我们测试了海拔（作为温度的替代物）和生产力与直翅目昆虫组合的四个生态相关形态特征之间的关系，这些特征与繁殖力（体型大小）、扩散（翅膀长度）、跳跃能力（后足长度）和捕食者检测（眼睛大小）有关。我们测量了在坦桑尼亚乞力马扎罗山（Kilimanjaro）沿广泛环境梯度采集的 160 种直翅目物种的特征，该环境梯度的海拔范围从海平面以上 790 米到 4410 米不等，植物生产力水平也不同。对于体型大小以外的特征，我们从体长回归中计算残差，以估计特征的变化，而与体型大小无关。贝叶斯分析表明，集合体的平均体型大小，以及相对翅膀长度、后足长度和眼睛大小的平均值，随着海拔的升高而降低。体型大小和相对眼睛大小也随着生产力的增加而降低。种系发生关系以及物种特异性适应都促成了这些模式。我们的结果表明，与低温（高海拔）相比，高温（低海拔）下直翅目昆虫组合具有更高的繁殖力、更好的扩散和逃避能力以及更好的捕食者检测能力。在低生产力的栖息地中，体型较大可能具有优势，因为饥饿的风险降低。同样，大眼睛大小可能具有优势，因为在植被覆盖低的栖息地中，有能力检测到捕食者，而在这些栖息地中，隐藏的可能性很少。我们的研究强调，温度和生产力的变化不仅导致种间体型大小的变化，而且还与影响生物在其环境中生态适应性的其他形态特征的独立变化有关。
