Elmer Matt C, Monro Keyne, Thompson Harley, Stuckey Aidan, Kellermann Vanessa
School of Biological Sciences, Monash University, Clayton, Victoria, Australia.
School of Agriculture Biomedicine and Environment, La Trobe University, Bundoora, Victoria, Australia.
Ecology. 2025 Sep;106(9):e70183. doi: 10.1002/ecy.70183.
Climate change threatens biodiversity and ecosystem services around the globe. Despite the importance of native bees as pollinators, there is evidence of global declines, and we know very little about how climate shapes their distributions now and into the future. In the current study, we combined large-scale seasonal field sampling and experimental acclimation to examine whether populations of an Australian bee, Exoneura robusta, vary in their capacity to adapt to different climates. Collecting female bees across a latitudinal cline and examining heat and cold tolerance, we found populations did not vary in their heat tolerance along a latitudinal gradient. In contrast, bees from higher latitudes tended to be more cold-tolerant than bees from lower latitudes, but the relationship between cold tolerance and latitude differed between summer and spring (post-winter). Such seasonal variation suggests that phenotypic plasticity plays a role in shaping cold tolerance, as bees are likely to belong to the same generation from summer to spring. To untangle the roles of plasticity and genetic variation in shaping variation in thermal tolerance across seasons, we acclimated adult females from three populations spanning the species' distributional range to either 21 or 26°C in glasshouses (approximating summer and spring/autumn temperatures experienced throughout their range). We then estimated heat and cold tolerance. Contrasting acclimation responses observed in the glasshouses to those observed in the field point to phenotypic plasticity in cold tolerance rather than genetic variation underpinning population variation. In contrast, heat tolerance varied little in the field and in our glasshouse experiments. These results suggest bees may have little capacity to increase their heat tolerance, which is high at ~47°C, via genetic or plastic responses as climate changes.
气候变化威胁着全球的生物多样性和生态系统服务。尽管本地蜜蜂作为传粉者至关重要，但有证据表明其数量在全球范围内呈下降趋势，而且我们对气候如何塑造它们当前及未来的分布了解甚少。在当前的研究中，我们结合了大规模的季节性野外采样和实验性驯化，以研究澳大利亚蜜蜂Exoneura robusta的种群在适应不同气候的能力上是否存在差异。我们在一个纬度梯度上采集雌蜂，并检测其耐热性和耐寒性，发现种群在沿纬度梯度的耐热性方面没有差异。相比之下，来自高纬度地区的蜜蜂往往比来自低纬度地区的蜜蜂更耐寒，但耐寒性与纬度之间的关系在夏季和春季（冬季过后）有所不同。这种季节性变化表明，表型可塑性在塑造耐寒性方面发挥了作用，因为从夏季到春季蜜蜂可能属于同一代。为了厘清可塑性和遗传变异在塑造不同季节热耐受性变异中的作用，我们将来自该物种分布范围内三个种群的成年雌蜂在温室中驯化到21或26°C（近似于它们在整个分布范围内经历的夏季和春季/秋季温度）。然后我们估计了它们的耐热性和耐寒性。将在温室中观察到的驯化反应与在野外观察到的反应进行对比，结果表明耐寒性存在表型可塑性，而非遗传变异是种群变异的基础。相比之下，耐热性在野外和我们的温室实验中变化不大。这些结果表明，随着气候变化，蜜蜂可能几乎没有能力通过遗传或可塑性反应来提高其耐热性，其耐热性在约47°C时就很高。
