The phylogenetic diversity and structure of the seasonally dry forests in the Neotropics

Abstract

AimExceptions to the quasi‐ubiquitous latitudinal diversity gradient (LDG) have been poorly studied. A reverse LDG, when species richness (SR) increases away from the Equator, has been suggested for several taxa and entire biomes. The Neotropical seasonally dry tropical forests (SDTF) are a well‐known example of a reverse LDG that could be caused by the climatic stability of Pleistocene Refugia and dispersion from distinct source areas. Here, we test these predictions under a spatial and phylogenetic framework.LocationNeotropics.TaxonWoody plants.MethodsWe used a recent species‐level seed plant phylogeny and the DRYFLOR dataset to evaluate the geographic patterns of phylogenetic diversity (PD) and structure of woody plant assemblages associated with the Neotropical SDTFs. We conducted spatial regressions to test the effect of climatic instability since the Last Glacial Maximum (LGM) on assemblages’ residual PD (controlling for SR) and null model analysis to evaluate their phylogenetic structure using the Net Relatedness Index.ResultsPhylogenetic diversity of the Neotropical SDTFs increased away from the Equator, likely driven by SR. This pattern was not related to climatic instability since the LGM. Phylogenetic structure of SDTF assemblages showed considerable spatial patterning, with significant phylogenetic clustering in the Mesoamerica and Caatinga regions.Main conclusionThe reverse latitudinal SR gradient of the Neotropical SDTF assemblages is mirrored by their PD. Phylogenetic history seems to have influenced such patterns differently across the Neotropics with no relationship to climatic stability since the LGM, where particular SDTF nuclei previously suggested as Pleistocene refugia served as cradles and source areas for the current diversity pattern of the biome.

Environmental Drivers of Diversification and Hybridization in Neotropical Butterflies

“…Interestingly, areas with highest species richness got low phylogenetic diversity (Figure 2C, blue grids), which may be a consequence of the recent increase in diversification rate in Heliconius (4.5 Ma) and the consequent cooccurrence of multiple young species in the Amazon and foothills of the eastern Andes (Rosser et al, 2012;Kozak et al, 2015). In agreement with this observation, previous research in both animals and plants have found high phylogenetic diversity in the eastern Andes of Colombia, Peru, and Ecuador (Fenker et al, 2014;Mendoza and Arita, 2014;Guedes et al, 2018;Arango et al, 2021;Velazco et al, 2021).…”

Tracking the xeric biomes of South America: The spatiotemporal diversification of Mandacaru cactus

“…The impact of Pleistocene climatic changes for Neotropical plant biogeography was proposed by a series of studies (e.g. Arango et al, 2021; Hubarth et al, 2021; Lavor et al, 2019; Leal et al, 2016; Mota et al, 2020), many of them highlighting climatic instability as an important driver of connectivity among populations due to range fluctuations and formation of forest corridors. Among them, species widely distributed in xeric habitats, such as the Neotropical cacti species of Pilosocereus (Bonatelli et al, 2014; Lavor et al, 2019), distributed in rock outcrops within Cerrado and SDTF, Euphorbia sect.…”

Phylogeography and morphometric variation in the Cinnamon Hummingbird complex: Amazilia rutila (Aves: Trochilidae)

“…Eugenes fulgens: Zamudio-Beltrán et al 2020). These habitat fluctuations are well documented as factors that promote population contractions, limiting gene flow (refugia hypothesis; Arango et al 2021), as well as expansions, resulting in zones of contact between distant populations, with current signals of shared haplotypes and polyphyletic patterns (e.g. Mesoamerican Amazilia complex: Jiménez and Ornelas 2016; White-chested Amazilia complex: Rodríguez-Gómez and Ornelas 2018).…”