Climatic and topographical correlates of plant palaeo- and neoendemism in a Mediterranean biodiversity hotspot

Abstract

Background and Aims Understanding the evolutionary and ecological forces contributing to the emergence of biodiversity hotspots is of outstanding importance to elucidate how they may withstand current climate changes. Here we explored patterns of phylogenetic and non-phylogenetic plant endemism in a Mediterranean biodiversity hotspot. We hypothesized that areas with wet and equable climatic conditions would be prone to long-term persistence of endemic lineages (palaeoendemism), whilst areas of recent local speciation (neoendemism) would be more related to harsher environmental conditions and to high topographical relief promoting speciation.Methods We focused on the Baetic-Rifan biodiversity hotspot (southern Iberian Peninsula and northern Morocco) in combination with molecular phylogenetic information and relative phylogenetic endemism (RPE), a recent phylogenetic measure of endemism, allowing us to discern centres of palaeo-from those of neoendemism. Using eco-geographical regions as study units, we explored correlations between both RPE and endemic species richness with precipitation-and temperature-related variables and with elevation range.Key Results Centres of neoendemism were concentrated towards the easternmost part of the hotspot, while centres of palaeoendemism were clustered in the vicinity of the Strait of Gibraltar. The RPE index, indicating more palaeoendemism, was positively correlated with total annual precipitation, while endemic species richness showed a poor correlation. In contrast, elevation range and mean annual temperature were poor predictors of RPE, despite elevation range showing a strong correlation with endemic species richness.Conclusions The Baetic-Rifan biodiversity hotspot shows clearly differentiated centres of neo-and palaeoendemism. Topographical relief may have driven evolutionary diversification of newly evolved species, while water availability seems more critical for the long-term persistence of ancient lineages in refuge areas of smoother topography. Given climatic trends towards increasing aridification, conservation planners should pay particular attention to preserve areas retaining older phylogenetic lineages, as these areas act as 'natural museums' of biodiversity within the Baetic-Rifan biodiversity hotspot.

Species and phylogenetic endemism in angiosperm trees across the Northern Hemisphere are jointly shaped by modern climate and glacial–interglacial climate change

“…Moreover, an association of endemism with a narrow extent of analogous modern climate was also significant in Europe and North America, supporting a role for this factor in promoting endemism. Consistent with our findings, water availability is found to be positively correlated with plant relative phylogenetic endemism in the Baetic‐Rifan biodiversity hotspot (Molina‐Venegas, Aparicio, Lavergne, & Arroyo, ). Chinese endemic plant species richness is also positively associated with modern temperature and precipitation (Feng et al, ).…”

Assessment of plant species diversity associated with the carob tree (Ceratonia siliqua, Fabaceae) at the Mediterranean scale

“…The debate about the status of the carob tree -native, or introduced for cultivation -in the Western Mediterranean (Ramón-Laca & Mabberley 2004) will remain open until adequate investigations such as phylogeographical and paleoecological studies are conducted. In the context of forthcoming research on the history of the carob tree in the Mediterranean, the extensive data survey reported here bore evidence of the presence of carob tree along a large ecological gradient in the Western Mediterranean, where it is very well integrated to spontaneous vegetation within hotspots of plant biodiversity well known to be also biogeographical refugia (Benabid & Cuzin 1997, Médail & Quézel 1999, Molina-Venegas et al 2017. Within the context of the aggravation of global changes, the ecological resilience capabilities have become a major issue in Mediterranean basin (see Thiébault & Moatti 2016).…”

Museums and cradles of diversity are geographically coincident for narrowly distributed Neotropical snakes

“…We then calculated the standardized effect size scores of PE and RPE (Molina-Venegas et al 2017). This score is the actual PE or RPE in a grid cell minus the mean value of the null PE distribution (from the 999 randomizations for each phylogeny) divided by the standard deviation of the null PE distribution.…”