The adaptedness of the floral phenotype in a relict endemic, hawkmoth-pollinated violet. 2. Patterns of variation among disjunct populations

Abstract

This study examines patterns of variation in quantitative floral traits among 18 disjunct populations of Viola cazorlensis (Violaceae), a relict endemic violet of south-eastern Spain. At all sites, the species is almost exclusively pollinated by a single species of day-flying hawkmoth. Differences between populations were significant for all traits examined, and population means exhibit a broad range of variation. When all characters are considered together, each population displays a unique combination of characters. Despite interpopulation differences in character means, local populations retain most of the variability of the entire species. Floral traits do not vary in unison among flowers, and at least four different subsets of independently varying traits are identifiable. Floral similarity between populations of V. cazorlensis was largely unrelated to geographic proximity, as revealed by analyses at both large and small geographic scales. The geographic pattern of floral variation among populations represents a random patchwork, with unique combinations of character means occurring randomly across the study region. Marked population differences in quantitative floral traits in spite of spatial constancy in the identity of pollinators, a disintegrated floral phenotype, and prevailingly random geographic variation among populations, suggest low adaptedness of the floral phenotype of V. cazorlensir to its current hawkmoth pollinators.