title: Constant, cycling, hot and cold thermal environments: strong effects on mean viability but not on genetic estimates.
abstract: It has frequently been suggested that trait heritabilities are environmentally sensitive, and there are genetic trade-offs between tolerating different environments such as hot and cold or constant and fluctuating temperatures. Future climate predictions suggest an increase in both temperatures and their fluctuations. How species will respond to these changes is uncertain, particularly as there is a lack of studies which compare genetic performances in constant vs. fluctuating environments. In this study, we used a nested full-sib/half-sib breeding design to examine how the genetic variances and heritabilities of egg-to-adult viability differ at high and low temperatures with and without daily fluctuations in temperatures using Drosophila melanogaster as a model organism. Although egg-to-adult viability was clearly sensitive to developmental temperatures, heritabilities were not particularly sensitive to developmental temperatures. Moreover, we found that egg-to-adult viabilities at different developmental temperatures were positively correlated, suggesting a common genetic background for egg-to-adult viability at different temperatures. Finding both a uniform genetic background coupled with rather low heritabilities insensitive to temperatures, our results suggest evolutionary responses are unlikely to be limited by temperature effects on genetic parameters or negative genetic correlations, but by the direct effects of stressful temperatures on egg-to-adult viability accompanied with low heritabilities.
authors.affiliation: Centre of Excellence in Evolutionary Research, Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland. tarmo.t.ketola@jyu.fi
authors.forename: T
authors.initials: T
authors.lastname: Ketola
authors.forename: V
authors.initials: V
authors.lastname: Kellermann
authors.forename: T N
authors.initials: TN
authors.lastname: Kristensen
authors.forename: V
authors.initials: V
authors.lastname: Loeschcke
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D005075:Biological Evolution; D001947:Breeding / Q000379:methods; D003080:Cold Temperature; D004331:Drosophila melanogaster / Q000235:genetics / Q000502:physiology*; D004777:Environment; D005260:Female; D056084:Genetic Fitness; D014644:Genetic Variation; D006358:Hot Temperature; D008018:Life Cycle Stages / Q000502:physiology; D008297:Male; D019655:Quantitative Trait, Heritable; D013312:Stress, Physiological; D015053:Zygote / Q000502:physiology