Data from: Strong and consistent natural selection associated with armour reduction in sticklebacks

AbstractMeasuring the strength of natural selection is tremendously important in evolutionary biology, but remains a challenging task. In this work, we analyse the characteristics of selection for a morphological change (lateral-plate reduction) in the threespine stickleback Gasterosteus aculeatus. Adaptation to freshwater, leading to the reduction or loss of the bony lateral armor, has indeed occurred in parallel on numerous occasions in this species. Completely-plated and low-plated sticklebacks were introduced into a pond, and the phenotypic changes were tracked for twenty years. Fish from the last generation were genotyped for the Ectodysplasin-A (Eda) locus, the major gene involved in armor development. We found a strong fitness advantage for the freshwater-type fish (in average, 20% for the freshwater morph, and 92% for the freshwater genotype). The trend is best explained by assuming that this fitness advantage is maximum at the beginning of the invasion and decreases with time. Such fitness differences provide a quantifiable example of rapid selection-driven phenotypic evolution associated to environmental change in a natural population., Usage notesGenotype at Eda and lateral plate phenotypesThe file contains the genotypic information used in the manuscript. For each fish are indicated: 1) the population, 2) the morph according to Bell et al. 2004 definition (based on the presence of keel plates), 3) the morph according to Zuiganov's definition (based on the number of plates on one side, 4) the bilateral number of plates, 5) the genotype at marker Stn382, 6) the genotype at marker Stn381. Three populations are indicated, Myrdalsvatn and Eikelandsvatn are both parental populations (genotyped in 2008), and Nygårdspark is the experimental population. The genotype is not available for all fish. Allele code corresponds to rough estimates of fragment sizes (more precise information is provided in the manuscript)data_dryad.txt