EVOLUTION OF LATITUDINAL CLINES IN REVERSE: HOW MUCH DO POPULATIONS LOSE DIFFERENTIATION UNDER ADAPTATION TO A NOVEL, COMMON ENVIRONMENT

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Predictable phenotypic, but not karyotypic, evolution of populations with contrasting initial history

Publication . Simões, Pedro; De mendonça fragata almeida, Inês; Seabra, Sofia G.; Faria, Gonçalo S.; Santos, Marta A.; Rose, Michael R.; Santos, Mauro; Matos, Margarida

The relative impact of selection, chance and history will determine the predictability of evolution. There is a lack of empirical research on this subject, particularly in sexual organisms. Here we use experimental evolution to test the predictability of evolution. We analyse the real-time evolution of Drosophila subobscura populations derived from contrasting European latitudes placed in a novel laboratory environment. Each natural population was sampled twice within a three-year interval. We study evolutionary responses at both phenotypic (life-history, morphological and physiological traits) and karyotypic levels for around 30 generations of laboratory culture. Our results show (1) repeatable historical effects between years in the initial state, at both phenotypic and karyotypic levels; (2) predictable phenotypic evolution with general convergence except for body size; and (3) unpredictable karyotypic evolution. We conclude that the predictability of evolution is contingent on the trait and level of organization, highlighting the importance of studying multiple biological levels with respect to evolutionary patterns.

2017-04Journal article

Open access

Different Genomic Changes Underlie Adaptive Evolution in Populations of Contrasting History

Publication . Seabra, Sofia G; De mendonça fragata almeida, Inês; Antunes, Marta; Faria, Gonçalo S; Santos, MA; Sousa, Vitor C; Simões, Pedro; Matos, Margarida

Experimental evolution is a powerful tool to understand the adaptive potential of populations under environmental change. Here, we study the importance of the historical genetic background in the outcome of evolution at the genome-wide level. Using the natural clinal variation of Drosophila subobscura, we sampled populations from two contrasting latitudes (Adraga, Portugal and Groningen, Netherlands) and introduced them in a new common environment in the laboratory. We characterized the genome-wide temporal changes underlying the evolutionary dynamics of these populations, which had previously shown fast convergence at the phenotypic level, but not at chromosomal inversion frequencies. We found that initially differentiated populations did not converge either at genome-wide level or at candidate SNPs with signs of selection. In contrast, populations from Portugal showed convergence to the control population that derived from the same geographical origin and had been long-established in the laboratory. Candidate SNPs showed a variety of different allele frequency change patterns across generations, indicative of an underlying polygenic basis. We did not detect strong linkage around candidate SNPs, but rather a small but long-ranging effect. In conclusion, we found that history played a major role in genomic variation and evolution, with initially differentiated populations reaching the same adaptive outcome through different genetic routes.

2018-03Journal article

Open access