Programa de Genética Humana, Facultad de Medicina, Instituto de Ciencias Biomédicas, Universidad de Chile, Santiago, Chile.
Institute of Integrative Biology, University of Liverpool, Liverpool, UK.
J Evol Biol. 2019 Aug;32(8):818-824. doi: 10.1111/jeb.13483. Epub 2019 May 13.
Evolutionary change of thermal traits (i.e., heat tolerance and behavioural thermoregulation) is one of the most important mechanisms exhibited by organisms to respond to global warming. However, the evolutionary potential of heat tolerance, estimated as narrow-sense heritability, depends on the methodology employed. An alternative adaptive mechanism to buffer extreme temperatures is behavioural thermoregulation, although the association between heat tolerance and thermal preference is not clearly understood. We suspect that methodological effects associated with the duration of heat stress during thermal tolerance assays are responsible for missing this genetic association. To test this hypothesis, we estimated the heritabilities and genetic correlations for thermal traits in Drosophila subobscura, using high-temperature static and slow ramping assays. We found that heritability for heat tolerance was higher in static assays (h = 0.134) than in slow ramping assays (h = 0.084), suggesting that fast assays may provide a more precise estimation of the genetic variation of heat tolerance. In addition, thermal preference exhibited a low heritability (h = 0.066), suggesting a reduced evolutionary response for this trait. We also found that the different estimates of heat tolerance and thermal preference were not genetically correlated, regardless of how heat tolerance was estimated. In conclusion, our data suggest that these thermal traits can evolve independently in this species. In agreement with previous evidence, these results indicate that methodology may have an important impact on genetic estimates of heat tolerance and that fast assays are more likely to detect the genetic component of heat tolerance.
热特性（即耐热性和行为体温调节）的进化变化是生物体应对全球变暖的最重要机制之一。然而，耐热性的进化潜力（估计为狭义遗传力）取决于所采用的方法。行为体温调节是缓冲极端温度的另一种适应机制，尽管耐热性和热偏好之间的关联尚不清楚。我们怀疑与耐热性测定期间热应激持续时间相关的方法效应是导致这种遗传关联缺失的原因。为了验证这一假设，我们使用高温静态和缓慢斜坡测定法，估计了黑腹果蝇的耐热性和热偏好的遗传力和遗传相关性。我们发现，在静态测定中耐热性的遗传力较高（h = 0.134），而在缓慢斜坡测定中耐热性的遗传力较低（h = 0.084），这表明快速测定法可能更准确地估计耐热性的遗传变异。此外，热偏好的遗传力较低（h = 0.066），表明该性状的进化反应较弱。我们还发现，无论如何估计耐热性，耐热性和热偏好的不同估计值之间没有遗传相关性。总之，我们的数据表明，这些热特性在该物种中可以独立进化。与先前的证据一致，这些结果表明，方法可能对耐热性的遗传估计有重要影响，并且快速测定法更有可能检测到耐热性的遗传成分。
