Behavioural responses to warming differentially impact survival in introduced and native dung beetles

Background: Anthropogenic changes are often studied in isolation but may interact to affect biodiversity. For example, climate change could exacerbate the impacts of biological invasions if climate change differentially affects invasive and native species. Behavioural plasticity may mitigate some of the impacts of climate change, but species vary in their degree of behavioural plasticity. In particular, invasive species may have greater behavioural plasticity than native species since plasticity helps invasive species establish and spread in new environments. This plasticity could make invasives better able to cope with climate change. Goal: Here our goal was to examine whether reproductive behaviours and behavioural plasticity vary between an introduced and a native Onthophagus dung beetle species in response to warming temperatures and how differences in behaviour influence offspring survival. Methods: Using a repeated measures design, we exposed small colonies of introduced O. taurus and native O. hecate to three temperature treatments, including a control, low warming, and high warming treatment, and then measured reproductive behaviours, including the number, size, and burial depth of brood balls. We reared offspring in their brood balls in developmental temperatures that matched those of the brood ball burial depth to quantify survival. Results: We found that the introduced O. taurus produced more brood balls and larger brood balls, and buried brood balls deeper than the native O. hecate in all treatments. However, the two species did not vary in the degree of behavioural plasticity in response to warming. Differences in reproductive behaviours did affect survival, such that warming temperatures had a greater effect on survival of offspring of native O. hecate compared to introduced O. taurus. Broader implications: Overall, our results suggest that differences in behaviour between native and introduced species is one mechanism through which climate change may exacerbate negative impacts of biological invasions.【研究背景】人类活动引发的环境变化常被单独研究，但这类变化之间可能产生交互作用，进而影响生物多样性。例如，若气候变化对入侵物种和本地物种的影响存在差异，则可能加剧生物入侵所带来的生态冲击。行为可塑性（behavioural plasticity）或许能够缓解气候变化带来的部分影响，但不同物种的行为可塑性程度存在差异。具体而言，入侵物种的行为可塑性往往高于本地物种——因为可塑性有助于入侵物种在新环境中定殖与扩散，这种特性可提升入侵物种应对气候变化的能力。 【研究目标】本研究旨在探究：在升温环境下，引入种与本地嗡蜣螂属（Onthophagus）粪金龟的繁殖行为及行为可塑性是否存在差异，以及这类行为差异如何影响子代存活率。 【研究方法】本研究采用重复测量设计，将引入种瘤背嗡蜣螂（O. taurus）与本地赫氏嗡蜣螂（O. hecate）的小型种群分别置于三种温度处理（对照、轻度升温、重度升温）环境中，随后对其繁殖行为指标进行测定，包括育幼球（brood ball）的数量、大小及埋藏深度。我们将子代置于与育幼球埋藏深度对应的发育温度环境中饲养，以量化子代存活率。 【研究结果】本研究发现：在所有温度处理组中，引入种瘤背嗡蜣螂所产的育幼球数量更多、体积更大，且育幼球埋藏深度也比本地赫氏嗡蜣螂更深。但两种粪金龟在应对升温时的行为可塑性程度并无显著差异。繁殖行为的差异确实会对子代存活率产生影响：与引入种瘤背嗡蜣螂的子代相比，升温对本地赫氏嗡蜣螂的子代存活率影响更为显著。 【研究启示】综上，本研究结果表明，本地物种与引入物种的行为差异，是气候变化加剧生物入侵负面影响的潜在机制之一。