Abstract
We compiled a checklist with all known endemic plants occurring in the Sierras of Córdoba and San Luis, an isolated mountainous range located in central Argentina. In order to obtain a better understanding of the evolutionary history, relationships and age of the regional flora, we gathered basic information on the biogeographical and floristic affinities of the endemics, and documented the inclusion of each taxon in molecular phylogenies. We listed 89 taxa (including 69 species and 20 infraspecific taxa) belonging to 53 genera and 29 families. The endemics are not distributed evenly, being more abundant in the lower than in the middle and upper vegetation belts. Thirty-two genera (60.3%) have been included in phylogenetic analyses, but only ten (18.8%) included local endemic taxa. A total of 28 endemic taxa of the Sierras CSL have a clear relationship with a widespread species of the same genus, or with one found close to the area. Available phylogenies for some taxa show divergence times between 7.0 – 1.8 Ma; all endemic taxa are most probably neoendemics sensu Stebbins and Major. Our analysis was specifically aimed at a particular geographic area, but the approach of analyzing phylogenetic patterns together with floristic or biogeographical relationships of the endemic taxa of an area, delimited by clear geomorphological features, could reveal evolutionary trends shaping the area.
Highlights
Why are endemic taxa important?‘The study and precise interpretation of the endemism of a territory constitute the supreme criterion, indispensable for arriving at any conclusions regarding the origin and age of its plant population
We compiled a list using online resources, in particular Zuloaga et al (2008) and the database of endemic plants of Argentina. We verified both the endemic status and the distribution of each taxon restricted to the Sierras CSL as defined by a cut-off altitude limit of 200 m
Of the relevant elements for studying endemism recognized by Stebbins and Major (1965), only the floristics of the Sierras CSL has been well studied (Cabido et al 1987, 1998; Giorgis et al 2011 and references therein), while the currently known fossil record is too sparse to be useful for studies of current vegetation (Leguizamon 1972, Balarino and Gutierrez 2006)
Summary
‘The study and precise interpretation of the endemism of a territory constitute the supreme criterion, indispensable for arriving at any conclusions regarding the origin and age of its plant population. It enables us better to understand the past and the transformations that have taken place. It provides us with a means of evaluating the extent of these transformations, the approximate epoch when they occurred, and the effects which they produced on the development of the flora and the vegetation’ (Braun-Blanquet 1923: 223). The study of plant endemism is important because it could improve our knowledge of the flora of a region in at least two different respects, which are briefly discussed below
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