Comparative floral and vegetative differentiation between two European Aquilegia taxa along a narrow contact zone

Abstract

Abstract. As a first step in determining the identity and relative importance of the evolutionary forces promoting the speciation process in two closely related European taxa of Aquilegia, we investigated the levels of morphological variation in floral and vegetative characters over the narrow region where their ranges enter into contact, and evaluate the relative importance of both types of traits in their differentiation. A total of 12 floral and ten vegetative characters were measured on 375 plants belonging to seven A. vulgaris populations and six A. pyrenaica subsp. cazorlensis populations located in southeastern Spain. Floral and vegetative morphological differentiation occur between taxa and among populations within taxa, but only vegetative characters (particularly plant height and leaf petiolule length) contribute significantly to the discrimination between taxa. Differentiation among populations within taxa is mostly explained by variation in floral traits. Consequently, morphological divergence between the two taxa cannot be interpreted as an extension of among-population differences occurring within taxa. Multivariate vegetative, but not floral, similarity between populations could be predicted from geographical distance. Moreover, the key role of certain vegetative traits in the differentiation of A. vulgaris and A. p. cazorlensis could possibly be attributable to the contrasting habitat requirements and stress tolerance strategies of the two taxa. These preliminary findings seem to disagree with the currently established view of the radiation process in the genus Aquilegia in North America, where the differentiation of floral traits seems to have played a more important role.

Adaptation to habitat inAquilegiaspecies endemic to Sardinia (Italy): Seed dispersal, germination and persistence in the soil

“…Furthermore, the adaptation of these two species to their microhabitats confirms the findings of Medrano et al (2006) and Bastida et al (2010) on the pivotal role of abiotic factors, as compared with pollination-related ones, in species differentiation of the Aquilegia genus in Europe, and in the Mediterranean region in particular, despite the overlap detected in the flowering periods of the two species.…”

“…Medrano et al (2006) found that local populations of two European Aquilegia species [A. vulgaris L. and A. pyrenaica DC. subsp.…”

Linking divergent selection on vegetative traits to environmental variation and phenotypic diversification in the Iberian columbines (Aquilegia)

“…All the traits studied varied among populations within taxa and between species or subspecies. Similar results were obtained comparing a wider set of vegetative and floral traits between populations of A. v. vulgaris and A. p. cazorlensis (Medrano et al. , 2006).…”

Population Genetics Methods Applied to a Species Delimitation Problem: Endemic Trumpet Daffodils (NarcissusSectionPseudonarcissi) from the Southern Iberian Peninsula

“…Another factor contributing to the outstanding diversity of Mediterranean floras is environmental heterogeneity, which has promoted ecological specialization and the natural fragmentation and isolation of conspecific populations (Thompson 2005;Hughes et al 2006;Frajman and Oxelman 2007;Martín-Bravo et al 2010). The diversifying role of plant specialization on specific substrates and its consequences for ecological speciation in the Baetic Ranges has often been emphasized in relation to dolomitic outcrops (Mota et al 2002(Mota et al , 2008, but the contribution of other similarly fragmented, infrequent habitat types to the high endemism rates characterizing the region has been infrequently considered (Medrano et al 2006;Medrano and Herrera 2008). All populations considered in the present study comprising the green group occurred in permanently waterlogged meadows (associated with permanent springs or small mountain streams) that were surrounded by xerophytic vegetation.…”