Data for: Plasticity in mosquito size and thermal tolerance across a latitudinal climate gradient

Variations in heat tolerance among populations can determine whether a
species can cope with ongoing climate change. Such variation may be
especially important for ectotherms whose body temperatures, and
consequently, physiological processes, are regulated by external
conditions. Additionally, differences in body size are often associated
with latitudinal clines, thought to be driven by climate gradients. While
studies have begun to explore variation in body size and heat tolerance
within species, our understanding of these patterns across large spatial
scales, particularly regarding the roles of plasticity and genetic
differences, remains incomplete. Here, we examine body size, as measured
by wing length, and thermal tolerance, as measured by the time to
immobilization at high temperatures (“thermal knockdown”), in populations
of the mosquito Aedes sierrensis collected from across a large latitudinal
climate gradient spanning 1300 km (34-44 °N). We find that
mosquitoes collected from lower latitudes and warmer climates were more
tolerant of high temperatures than those collected from higher latitudes
and colder climates. Moreover, body size increased with latitude and
decreased with temperature, a pattern consistent with James’ rule, which
appears to be a result of plasticity rather than genetic variation. Our
results suggest that warmer environments produce smaller and more
thermally tolerant populations.

种群间耐热性的差异，可决定某一物种能否应对当前持续的气候变化。这类变异对于外温动物（ectotherms）而言尤为关键——其体温乃至生理过程均由外界环境调控。此外，体型差异常与纬度梯度相关联，该现象被认为由气候梯度驱动。尽管已有研究开始探索物种内部体型与耐热性的变异，但我们对大空间尺度下的这类模式的认知仍不完善，尤其是关于表型可塑性（plasticity）和遗传差异所扮演的角色。本研究以翅长作为体型的衡量指标、以高温下的麻痹时间（即"热击倒时间（thermal knockdown）"）作为耐热性的检测指标，对横跨1300公里、纬度跨度为34°N至44°N的大纬度气候梯度中采集的锡尔森伊蚊（Aedes sierrensis）种群进行了检测。研究发现，采自低纬度温暖气候区域的蚊虫，其高温耐受性高于采自高纬度寒冷气候区域的个体。此外，体型随纬度升高而增大、随环境温度升高而减小，这一模式符合詹姆斯法则（James’ rule），且该现象似乎由表型可塑性而非遗传变异所致。本研究结果表明，温暖环境会孕育出体型更小但耐热性更强的种群。