Stahl Lisa, Johansson Frank
Department of Ecology and Genetics, Animal Ecology Program Uppsala University Uppsala Sweden.
Ecol Evol. 2024 Jun 13;14(6):e11502. doi: 10.1002/ece3.11502. eCollection 2024 Jun.
Identifying how temperature and food resources affect interactions between species is important for understanding how climate change will shape community structure in the future. Here, we tested how temperature and resource density affect survival and growth in the larval stage of two coexisting odonates: the damselfly and the dragonfly . We performed a laboratory experiment at two temperatures (21 and 24°C) with two resource densities. We estimated the timing of egg hatching of individual egg clutches and thereafter the larval growth rate-, survival- and size-mediated priority effects under interspecific conditions. Eggs of both species hatched slightly faster at 24°C, and eggs started hatching approximately 1 day earlier than eggs. However, this earlier hatching did not result in a size-mediated priority effect, that is, a higher predation on the later hatching . Nevertheless, larvae were significantly larger than at hatching. Growth rate and survival were significantly higher: (1) at 24°C compared with 21°C, (2) at high compared with low-resource density and (3) in compared with . Several significant interaction effects between resource density and temperature and between temperature and species were found. At high temperature, had a higher growth rate than , but no difference in growth rate between species was found at low temperature. Additionally, a high-resource density resulted in a higher growth rate in both species, but only under high temperature. There was a negative relationship between growth rate and survival in both species, suggesting that the higher growth rate of larvae was to some degree driven by intraguild predation and/or cannibalism. Our results imply that resource levels interact with temperature to affect interactions between the species.
确定温度和食物资源如何影响物种间的相互作用，对于理解气候变化将如何塑造未来的群落结构至关重要。在此，我们测试了温度和资源密度如何影响两种共存的蜻蜓目昆虫幼虫阶段的存活和生长：豆娘和蜻蜓。我们在两种温度（21和24°C）以及两种资源密度下进行了实验室实验。我们估计了单个卵块的孵化时间，进而估计了种间条件下幼虫生长速率、存活和大小介导的优先效应。两种物种的卵在24°C时孵化略快，且[豆娘的]卵比[蜻蜓的]卵大约早1天开始孵化。然而，这种较早孵化并未导致大小介导的优先效应，即对较晚孵化的[蜻蜓]捕食率更高。尽管如此，[豆娘]幼虫在孵化时明显比[蜻蜓]大。生长速率和存活率显著更高：（1）24°C时高于21°C，（2）高资源密度时高于低资源密度，以及（3）[豆娘]高于[蜻蜓]。我们发现了资源密度与温度之间以及温度与物种之间的几个显著交互作用。在高温下，[豆娘]的生长速率高于[蜻蜓]，但在低温下未发现物种间生长速率的差异。此外，高资源密度导致两种物种的生长速率都更高，但仅在高温下如此。两种物种的生长速率与存活率之间均呈负相关，这表明幼虫较高的生长速率在某种程度上是由集团内捕食和/或同类相食驱动的。我们的结果表明，资源水平与温度相互作用，从而影响物种间的相互作用。
