Range-Wide Variation in the Ecological Niche and Floral Polymorphism of the Western Mediterranean GeophyteNarcissus dubiusGouan

Abstract

Editor: Félix ForestPremise of research. Comparative studies of variation in the ecology and genetics of natural plant populations located at the limits and in the center of a species range provide fundamental insights into the historical formation of species distribution patterns.Methodology. In this study, we quantify variation in the ecological niche and the expression of a floral polymorphism across the range of the Mediterranean geophyte Narcissus dubius Gouan. An exhaustive data set of known locations was compiled to distinguish groups of geographically central and peripheral populations in both Spain and France. These occur across a double climatic gradient. First, there is a gradient from a hot and dry Mediterranean climatic regime in eastern Spain to a milder Mediterranean climatic regime in southern France (lower maximum temperature and shorter summer drought). Second, there is a shift to a more continental climate in peripheral populations in inland Spain. We also modeled the current climatic niche and produced historical projections of potential glacial refugia for this species.Pivotal results. Peripheral populations showed consistent patterns of ecological niche differences with a less rupicolous ecology, more bare soil, and a higher cover of annual species. The ecological niche was more variable among peripheral populations than among central populations. Peripheral populations showed a repeated pattern of loss of stigma-height polymorphism and floral traits indicative of a reproductive strategy based on within-morph mating (probably selfing to assure seed set). Climate models indicate that contemporary peripheral populations (particularly in Spain) occur in areas that were least likely to have served as glacial refugia.Conclusions. Historical isolation and recolonization may have shaped contemporary patterns of ecological niche and reproductive trait variation among central and peripheral populations.

Ecological niche differentiation in peripheral populations: a comparative analysis of eleven Mediterranean plant species

“…in a Mediterranean-type climate with a summer drought. The only difference between central and peripheral populations here is the occurrence of shorter summer-drought period and slightly cooler mean average temperatures in peripheral populations (Papuga et al 2015).…”

“…We then randomly selected one species per family, except for the Asteraceae for which three species, each in a different clade, were selected. We included one common nonlisted species, Narcissus dubius, which was the subject of a previous study and for which we had previously analysed a similar dataset (Papuga et al 2015). A final list of 11 species (Table 1, Fig.…”

“…This trend is also observed in terms of the total species richness per quadrat assessed with the contact point method. It is possible that local climatic conditions may influence this result; peripheral populations occur in a less xeric Mediterranean-type climate than do most of the central populations (Papuga et al 2015). This may determine higher species diversity in peripheral locations.…”

“…A particularly interesting situation for the study of ecological differentiation in central and peripheral populations concerns the flora of southern France where many western Mediterranean species occur at their northern range limits (Jahandiez 1937, Quézel and Médail 2003, Noble and Diadema 2011, Papuga et al 2015, often in peripheral isolates (Medail et al 2002, Lhotte et al 2014). These patterns are closely associated with the geological and climatic history of the region (Thompson 2005, López de Heredia et al 2007, Médail and Diadema 2009, Feliner 2014.…”

Biogeographical network analysis of plant species distribution in the Mediterranean region

“…Thus, one particular feature of such climatic transition area is the high proportion of population isolated at the periphery of their main range (Thompson, 2005), either at the rear or at the leading edge of their distribution (Hampe & Petit, 2005). However, spatial patterns alone do not inform on the evolutionary isolation of such populations, could it be of recent dispersal following Last Glacial Maximum (Lumaret et al, 2002), or long-term persistence in a given refugia (Médail & Diadema, 2009;Papuga et al, 2015). Thus, integrating phylogenies within bioregionalization would prove informative to analyze historical events that have shaped current spatial patterns of biodiversity (Nieto Feliner, 2014), and capture the evolutionary relationship among bioregions (Holt et al, 2013).…”