Sexual Selection as an Engine for Adaptation to Changing Environments

• Applicant: Professor Dr. Klaus Reinhardt, since 7/2019
• Subject Area: Evolution, Anthropology
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 412226825

• Final Report Year: 2024

Final Report Abstract

Natural and sexual selection are two powerful evolutionary forces. Recent work has asked whether the two forces are aligned or work in opposing directions, and if aligned, whether net selection is stronger on males compared to females so that populations can purge deleterious alleles at a low demographic cost. For sexual selection to purge deleterious alleles from a population and so strengthen natural selection, sexually selected traits must be conditiondependent, and environmental conditions must modify the fitness landscape of sexually selected traits. We found meta-analytical and empirical support for all these assumptions and predictions. (1) Empirically, we first, show that food restriction in the simultaneously hermaphroditic freshwater snail Physa acuta elevated the opportunity for selection in both sex functions but the G–matrix remained largely stable suggesting that sexual selection does not strongly interfere with the ability to adapt to novel environments. (2) Second, using the red flour beetle Tribolium castaneum as a model system, we found that stronger sexual selection magnifies detrimental heat stress effects in males but relaxed negative effects in females. This finding suggests sexual selection can reverse sex differences in thermal sensitivity and alter sex-specific selection on alleles associated with heat tolerance. Assuming that sexual selection and natural selection are aligned to favour the same genetic variants under environmental stress, our findings support the idea that sexual selection on males may promote the adaptation to current global warming. (3) In the same species, we show third, that there was no sex-specific effect of dietary stress on reproductive success and the opportunity for selection, suggesting that male fitness is not more condition-dependent than female fitness. (4) Fourth, looking at a third environmental factor, population density, we found that higher densities imposed by a larger group size amplified the opportunity for pre-copulatory sexual selection in females and, to a smaller extent, also in males. Higher densities resulted in a steeper male sexual selection gradient. (5) Meta-analytically we confirmed that net selection is stronger on males than females. We also provide preliminary evidence that this difference is associated with sexual selection, supporting a key assumption required for sexual selection to support adaptation.

Publications

• Assortative Mating in Animals and Its Role for Speciation. The American Naturalist, 194(6), 865-875.
  Janicke, Tim; Marie-Orleach, Lucas; Aubier, Thomas G.; Perrier, Charles & Morrow, Edward H.
  
• Environmental effects on the genetic architecture of fitness components in a simultaneous hermaphrodite. Journal of Animal Ecology, 91(1), 124-137.
  Janicke, Tim; Chapuis, Elodie; Meconcelli, Stefania; Bonel, Nicolas; Delahaie, Boris & David, Patrice
  
• Sexual selection and sexual size dimorphism in animals. Biology Letters, 17(9), 20210251.
  Janicke, Tim & Fromonteil, Salomé
  
• Stronger net selection on males across animals. eLife, 10.
  Winkler, Lennart; Moiron, Maria; Morrow, Edward H. & Janicke, Tim
  
• Systematic review reveals multiple sexually antagonistic polymorphisms affecting human disease and complex traits. Evolution, 75(12), 3087-3097.
  Harper, Jon Alexander; Janicke, Tim & Morrow, Edward H.
  
• The Scope for Postmating Sexual Selection in Plants. Trends in Ecology & Evolution, 36(6), 556-567.
  Tonnabel, Jeanne; David, Patrice; Janicke, Tim; Lehner, Arnaud; Mollet, Jean-Claude; Pannell, John R. & Dufay, Mathilde
  
• Diet quality impairs male and female reproductive performance and affects the opportunity for selection in an insect model. Ecology and Evolution, 12(11).
  Winkler, Lennart & Janicke, Tim
  
• Sexual selection moderates heat stress response in males and females. Functional Ecology, 36(12), 3096-3106.
  Moiron, Maria; Winkler, Lennart; Martin, Oliver Yves & Janicke, Tim
  
• Population density affects sexual selection in an insect model. Functional Ecology, 37(10), 2734-2747.
  Winkler, Lennart; Eilhardt, Ronja & Janicke, Tim
  
• Sexual selection in females and the evolution of polyandry. PLOS Biology, 21(1), e3001916.
  Fromonteil, Salomé; Marie-Orleach, Lucas; Winkler, Lennart & Janicke, Tim