Jones Laura J, Miller Douglas A, Schilder Rudolf J, López-Uribe Margarita M
Intercollege Graduate Degree Program in Ecology The Pennsylvania State University University Park Pennsylvania USA.
Department of Entomology, Center for Pollinator Research The Pennsylvania State University University Park Pennsylvania USA.
Ecol Evol. 2024 Feb 15;14(2):e10945. doi: 10.1002/ece3.10945. eCollection 2024 Feb.
Climate change presents a major threat to species distribution and persistence. Understanding what abiotic or biotic factors influence the thermal tolerances of natural populations is critical to assessing their vulnerability under rapidly changing thermal regimes. This study evaluates how body mass, local climate, and pathogen intensity influence heat tolerance and its population-level variation (SD) among individuals of the solitary bee . We assess the sex-specific relationships between these factors and heat tolerance given the differences in size between sexes and the ground-nesting behavior of the females. We collected . individuals from 14 sites across Pennsylvania, USA, that varied in mean temperature, precipitation, and soil texture. We measured the critical thermal maxima (CT) of . individuals as our proxy for heat tolerance and used quantitative PCR to determine relative intensities of three parasite groups-trypanosomes, (mollicute bacteria), and (microsporidian). While there was no difference in CT between the sexes, we found that CT increased significantly with body mass and that this relationship was stronger for males than for females. Air temperature, precipitation, and soil texture did not predict mean CT for either sex. However, population-level variation in CT was strongly and negatively correlated with air temperature, which suggests that temperature is acting as an environmental filter. Of the parasites screened, only trypanosome intensity correlated with heat tolerance. Specifically, trypanosome intensity negatively correlated with the CT of female . but not males. Our results highlight the importance of considering size, sex, and infection status when evaluating thermal tolerance traits. Importantly, this study reveals the need to evaluate trends in the variation of heat tolerance within and between populations and consider implications of reduced variation in heat tolerance for the persistence of ectotherms in future climate conditions.
气候变化对物种分布和存续构成重大威胁。了解哪些非生物或生物因素影响自然种群的热耐受性，对于评估它们在快速变化的热环境下的脆弱性至关重要。本研究评估了体重、当地气候和病原体强度如何影响独居蜂个体的耐热性及其种群水平的变异（标准差）。鉴于两性之间的体型差异以及雌性的地面筑巢行为，我们评估了这些因素与耐热性之间的性别特异性关系。我们从美国宾夕法尼亚州的14个地点收集了……个体，这些地点的平均温度、降水量和土壤质地各不相同。我们测量了……个体的临界热最大值（CT）作为耐热性的指标，并使用定量PCR来确定三种寄生虫群体——锥虫、（柔膜细菌）和（微孢子虫）的相对强度。虽然两性之间的CT没有差异，但我们发现CT随体重显著增加，并且这种关系在雄性中比在雌性中更强。气温、降水量和土壤质地均不能预测两性的平均CT。然而，CT的种群水平变异与气温呈强烈负相关，这表明温度起到了环境筛选的作用。在筛选的寄生虫中，只有锥虫强度与耐热性相关。具体而言，锥虫强度与雌性……的CT呈负相关，但与雄性无关。我们的结果强调了在评估耐热性特征时考虑体型、性别和感染状况的重要性。重要的是，本研究揭示了有必要评估种群内部和种群之间耐热性变异的趋势，并考虑耐热性变异减少对未来气候条件下变温动物存续的影响。
