Meta-analysis reveals that phenotypic plasticity and divergent selection promote reproductive isolation during incipient speciation

• Published in: Nature ecology & evolution Vol. 9; no. 5; pp. 833 - 844
• Main Authors: Jarrett, Benjamin J. M., Downing, Philip A., Svensson, Erik I.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.05.2025
• Subjects: 631/181/2475; 631/181/759; Animals; Arthropods - genetics; Arthropods - physiology; Biological and Physical Anthropology; Biomedical and Life Sciences; Ecology; Evolutionary Biology; Genetic Speciation; Life Sciences; Paleontology; Phenotype; Reproductive Isolation; Selection, Genetic; Vertebrates - genetics; Vertebrates - physiology; Yeasts - genetics; Yeasts - physiology; Zoology
• ISSN: 2397-334X
• DOI: 10.1038/s41559-025-02687-7

The evolution of reproductive isolation is a key evolutionary process, but the factors that shape its development in the early stages of speciation require clarification. Here, using a meta-analysis of 34 experimental speciation studies on arthropods, yeast and vertebrates, we show that populations subject to divergent selection evolved stronger reproductive isolation compared with populations that evolved in similar environments, consistent with ecological speciation theory. However, and contrary to predictions, reproductive isolation did not increase with the number of generations. Phenotypic plasticity could partly explain these results as divergent environments induce a plastic increase in reproductive isolation greater than the effect of divergent selection, but only for pre-mating isolating barriers. Our results highlight that adaptive evolution in response to different environments in conjunction with plasticity can initiate a rapid increase in reproductive isolation in the early stage of speciation. The authors examine factors affecting reproductive isolation in the early stages of speciation by collating data from 34 experimental speciation studies in 15 species ranging from yeast to vertebrates. They show that both phenotypic plasticity and divergent selection pressures accelerate the emergence of reproductive isolation, with plasticity promoting pre-mating isolation barriers in particular.