Pleistocene range expansions might explain striking disjunctions between eastern Brazil, Andes and Mesoamerica inLeandras.str. (Melastomataceae)

Abstract

Leandra s.str. clade has around 200 species nearly restricted to eastern Brazil. Most species in this group are narrow endemics, but a few present striking disjunct distributions between eastern Brazil and Andes or Mesoamerica. Given the predominantly “montane” distribution observed in most Leandra s.str., we hypothesized that cyclical range expansions during colder Pleistocene periods, followed by local extinctions during warmer interglacial periods, could have shaped the distribution of the disjunct species in this clade. In order to gather support for this biogeographical scenario in a phylogenetic framework, the species that occur outside eastern Brazil were identified, ages of the dispersal events estimated, climatic niche models for the disjuncts were generated, and the climatic envelope of these species compared. Our results place all dispersal events from eastern Brazil to Andes or Mesoamerica during the Pleistocene. Climatic niche modeling indicates a potential range expansion during the Pleistocene colder times for the disjunct species. Although the surpassing of the “dry diagonal” could have been facilitated during glacial periods, this open corridor is an effective barrier for Leandra, given the reduced number of species that dispersed beyond an eastern Brazilian origin. Additionally, the disjunct species do not present significant differences in their climatic envelopes to the non‐disjunct species. Our results provide support to a short‐dispersion/stepping‐stone migration scenario to account for the observed disjunctions in this clade. Range expansions during Pleistocene colder periods followed by local extinctions during interglacial periods could have shaped the distribution of Leandra s.str.

Two new species of Miconia s.lat. (Melastomataceae) from Espírito Santo, Brazil

“…Additionally, to exclude the immediate area around the known localities from the background, a buffer of 100 km in diameter was generated for each known point and subtracted from the main mask. We extracted the values for all bioclim layers of each coordinate and calculated the mean of each species (Reginato and Michelangeli 2019). The area under the curve (AUC) of the receiver operating characteristic (ROC) was used as evaluation criterion.…”

“…The extracted climatic values were summarized with a principal component analysis (PCA) using the R package ade4 ver. 1.7.6 (Dray and Dufour 2007), and convex hulls were plotted per group under comparison (Reginato and Michelangeli 2019). Values of elevation of each specimen were extracted through the R package elevatr ver.…”

Linking South American dry regions by the Gran Chaco: Insights from the evolutionary history and ecological diversification of Gomphrena s.str. (Gomphrenoideae, Amaranthaceae)

“…Even though the floristic composition shared between the eastern and western dry diagonals seems weak (Sarmiento, 1975; Ab'Saber, 1977; Prado & Gibbs, 1993; Prado, 2000; Linares‐Palomino et al, 2003; Pennington et al, 2009; Linares‐Palomino et al, 2011, 2015; Dryflor et al, 2016), several taxonomic groups have been recorded with taxa distributed in both arid regions (plants: Skytanthus Meyen, Apocynaceae, Prado, 2003; Paniceae, Poaceae, Zuloaga et al, 2007; Leandra Raddi, Melastomataceae, Reginato & Michelangeli, 2019; Bulnesia Gay, Zygophyllaceae, Böhnert et al, 2020; animals: Rhophitinae, Halictidae, Zanella & Martins, 2003). Among arid‐adapted taxa, the plant genus Gomphrena L. (Gomphrenoideae, Amaranthaceae Juss.)…”

Advances in biogeography in the age of a new modern synthesis

“…Two of the papers explore the biogeographic patterns of the Brazilian Atlantic Forest region, a major biodiversity hotspot of the world (Myers et al, ) and a fascinatingly rich, yet still poorly known, biogeographic region (Fiaschi & Pirani, ). Reginato & Michelangeli () document a striking amphitropical‐like disjunction in the melastome genus Leandra s. str. The disjunctions in Leandra are between eastern Brazil with high species concentration in the Brazilian Atlantic Forests, the Andes and Mesoamerica, and they have been found to be of recent origin, which is a general characteristic of typical amphitropical disjunctions in flowering plants (Wen & Ickert‐Bond, ; Simpson et al, ).…”