Complex patterns of environmental niche evolution in Iberian columbines (genus Aquilegia, ranunculaceae)

Aims This study explores the patterns of niche differentiation in a group of seven closely related columbines(genus Aquilegia,ranunculaceae)from the Iberian Peninsula.Populations of these columbines are subject to complex patterns of divergent selection across environ-ments,which partly explain the taxonomic structure of the group.This suggests the hypothesis that niche divergence must have occurred along the process of diversification of the group.Methods We used maxEnt to build environmental niche models of seven subspecies belonging to the three species of Aquilegia present in the Iberian Peninsula.From these models,we compared the envi-ronmental niches through two different approaches:ENmtools and multivariate methods.Important FindingsmaxEnt distributions conformed closely to the actual distribution of the study taxa.ENmtools methods failed to uncover any clear patterns of niche differentiation or conservatism in Iberian columbines.multivariate analyses indicate the existence of dif-ferentiation along altitudinal gradients and along a gradient of climatic conditions determined by the summer precipitation and temperatures.However,climatic conditions related to winter tem-perature and precipitation,as well as soil properties,were equally likely to show conservatism or divergence.The complex patterns of niche evolution we found suggest that Iberian Columbines have not been significantly constrained by forces of niche conservatism,so they could respond adaptively to the fast and profound climate changes in the Iberian Peninsula through the glacial cycles of the Pleistocene.

comLocal adaptation to distinct elevational cores contributes to current elevational divergence of two Aquilegia vulgaris subspecies

Aims Phenotypic plasticity and local adaptation of populations at their distributional limits are crucial to understand species colonization and persistence in novel or marginal environments,as well as spe-cies divergence and niche width evolution.We assess the contri-bution of these processes to shape current elevational limits and determine elevational phenotypic divergence between two subspe-cies of Aquilegia vulgaris(subsp.vulgaris and nevadensis).Methods We conducted sowing and transplant experiments considering four elevations throughout the current elevational range of A.vulgaris in southern Iberian Peninsula.Experiments were designed to explore,on the one hand,local adaptation through three components of performance(germination,survival and growth)and,on the other hand,the phenotypic differentiation and/or plasticity associated to local adaptation.Four populations per subspecies(three from the elevational core and one from the elevational boundary)were used as seed sources.Patterns of local adaptation and phenotypic differentiation are examined in the context of the‘centre-periphery’hypothesis.Important Findings Central populations of both subspecies performed better at their local elevations while marginal populations were maladapted,confirming the hypothesis and contributing to explain the current elevational segregation of these subspecies.Density of glandular pubescence and germination timing seem to be related to local adaptation,through phenotypic differentiation between subspe-cies or elevations.The widespread subsp.vulgaris showed signals of adaptive plasticity in the timing of germination while it was not the case in the endemic subsp.nevadensis.

Plant performance and morphofunctional differentiation in response to edaphic variation in Iberian columbines: cues for range distribution?

Aims Experimental studies of the response to environmental variation of closely related taxa are needed to understand the mechanisms underly-ing phenotypic divergence,habitat segregation and range span within a radiating genus.We explored the magnitude of phenotypic differenti-ation and adaptive plasticity in relation to edaphic variation and its sig-nificance for habitat segregation and range span in Iberian columbines.Methods We performed a common garden experiment varying soil type(cal-careous vs.siliceous)and depth(rocky-shallow vs.deep)with two pairs of widespread and narrowly distributed subspecies of Iberian columbines:Aquilegia vulgaris(subspp.vulgaris and nevadensis)and Aquilegia pyrenaica(subspp.pyrenaica and cazorlensis).We com-pared tolerance to edaphic variation,trait differentiation and adaptive plasticity of 10 morpho-functional traits between species and distri-bution ranges.additionally,we obtained estimates of the competitive environment faced by each taxon in two to four populations per taxa.Important Findingsresults partially support hypotheses of higher competitive ability and tolerance to edaphic variation in widespread than in narrow endemic taxa.at the species level,the widely distributed taxon was the most tolerant to edaphic variation.Within species,no consistent pattern emerged since the population from the most widespread subspecies was the most tolerant in A.vulgaris but not in A.pyr-enaica.Columbines were differentiated in many traits at species and range level.However,the pattern of differentiation does not fully support the hypothesis of higher specialization and stress toler-ance in narrow endemics.although plasticity was generally low,the results support the hypothesis of adaptive plasticity in widespread but not in restricted taxa at least at species level.Ecological differences(adaptive plasticity and competitive ability among others)may have contributed to phenotypic divergence and edaphic niche segregation,as well as to differences in range span among columbines.