Spatiotemporal variation in the relative fitness of a northern and a southern ecotype of Arabidopsis thaliana

Abstract: Terrestrial plants exist in almost every habitat on the earth, ranging from warm and moist tropical rainforests, hot and dry deserts, and to cold and barren tundras. Furthermore, a single species may encounter different climatic conditionshabitats within its range distribution which climatic conditions differs from one to another. In this study, I examine the flowering phenology and fitness of two locally adapted genotypes of Arabidopsis thaliana, one from the southern range limit (Italy) and one from the northern range limit (Sweden) in Europe, in an outdoor common-garden experiment in Uppsala. Flowering start was recorded to characterize flowering phenology, whilst survival and fecundity was recorded to characterize fitness. Flowering start differed significantly between the two genotypes as with the Swedish genotype startinged flowering 24 days later than the Italian genotype. The Italian genotype had higher fitness (number of fruits per seedling planted), which was due to a slightly higher survival and fecundity. The relative fitness of the two genotypes was thus intermediate to that observed in reciprocal transplants between the native sites of origin of the two populations.