Eco-geographical factors affecting richness and phylogenetic diversity patterns of high-mountain flora in the Iberian Peninsula

Abstract

Many studies have highlighted the importance of mountain ecosystems as hotspots of biodiversity and endemism. In this study, we used biogeographic partitioning to explore the diversity patterns of high-mountain flora in south-western Europe by analysing the richness of the main floristic elements in relation to geographical and ecological factors (climate, isolation, elevation, etc.). Taxa that inhabit above 1600 m a.s.l. in the Iberian Peninsula were selected using bibliographic sources. Hierarchical agglomerative clustering and non-metric multidimensional scaling (NMDS) were used to explore the patterns of taxonomic diversity across the main biogeographic elements. Six environmental variables were calculated to account for inter-range variation in species richness and biogeographic elements. The results showed that at a broad scale, the main floristic elements correlated with specific eco-geographical factors. The Arctic-Boreal element was strongly, negatively correlated with summer drought and showed a higher taxonomic distinctness than expected. The Iberian endemic element was related to isolation and maximum elevation and although it was the richest element, it demonstrated a relatively low taxonomic diversity, in particular in the Baetic Range. Biogeographic origin is an important driver of the diversity patterns of high-mountain flora. In the Iberian Peninsula, these patterns show a North-South gradient, which reflects historical processes of migration and speciation that were constrained by climatic fluctuations during the Ice Ages. Although species richness is the usual biodiversity measure considered in conservation strategies, the use of taxonomically related indices helps to understand better the general diversity patterns and to better document strategies of biodiversity conservation.

Distribución espacial y rasgos ecológicos de la flora endémica de los Pirineos

“…Similar results are described by Jimenez-Alfaro (2008) in the Cantabrian Range. This issue needs further investigation in order to research not only the role of the Pyrenees as a refuge during the glacial maximum, but also as a radiation center in the interglacials (Hewitt, 2004;Loidi et al, 2015).…”

“…Both, transitions from interglacial to glacial state and from glacial to interglacial, increased connectivity between mountain ranges like Sierra Nevada, the Pyrenees, the Alps or Carpathians, which share alpine taxa (Küpfer, 1974;Tutin et al, 1964Tutin et al, -1980Villar et al, 2001 and2003;Blanca, 2002;Aeschimann et al, 2004;Vargas, 2003;Castroviejo, 1986Castroviejo, -2015. These processes have been also documented in the Iberian Peninsula (Loidi et al, 2015;Buira et al, 2017). During interglacial periods, isolation of plant population in high altitudes have been predominant, triggering speciation processes that sometimes were completed before a new glacial cycle started (Rešetnik et al, 2013;Roquet et al, 2013;Deng et al, 2015) and therefore originating endemic species.…”

“…Although endemic species have concentrated research effort for different scientific interest (Favarger & Siljak-Yakovlev, 1986;Segarra-Moragués & Catalán, 2008;McMullen, 2009) we want to point out two major points. First, their restricted distribution often requires priority conservation politics (Médail & Verlaque, 1997;Dirnböck et al, 2011;Swenson et al, 2012;Huang et al, 2016) and second, they are valuable targets in evolutionary biology (Segarra-Moragués et al, 2007;Ikeda & Setoguchi, 2007;Casazza et al, 2008;Schön-swetter & Schneeweiss, 2009;García et al, 2012;Loidi et al, 2015).…”

Diversity Assessment of Lotic Macroalgal Flora by the Application of Taxonomic Distinctness Index

“…Herein, we showed the differences between TDI results and typical lotic macroalgal diversity found previously. So, we suggest that TDI should be used as a complementary measure to species richness, which would favors a more accurate definition of biodiversity conservation priorities (Loidi et al 2015). For instance, a species without close relations to any others would have higher priority for conservation than a species with many close relatives (Warwick & Clarke 2001).…”

“…Although species richness have been used to assess the diversity in conservation programs, the taxonomic indices as TDI would help to understand better the general diversity patterns and to improve strategies of biodiversity conservation (Loidi et al 2015), not only for stream macroalgae. Furthermore, TDI could be used in broad scale geographical comparisons of biodiversity, regarding more ecological questions, mainly those related to contrasting habitats.…”