Adjacency and Area Explain Species Bioregional Shifts in Neotropical Palms.

Cintia G Freitas,Rosane G Collevatti,Advaldo C Souza-Neto,Christine D Bacon

doi:10.3389/fpls.2019.00055

Cintia G Freitas, Rosane G Collevatti + Show 2 more

Open Access

https://doi.org/10.3389/fpls.2019.00055

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Abstract

Environmental and geographical variables are known drivers of community assembly, however their influence on phylogenetic structure and phylogenetic beta diversity of lineages within different bioregions is not well-understood. Using Neotropical palms as a model, we investigate how environmental and geographical variables affect the assembly of lineages into bioregions across an evolutionary time scale. We also determine lineage shifts between tropical (TRF) and non-tropical (non-TRF) forests. Our results identify that distance and area explain phylogenetic dissimilarity among bioregions. Lineages in smaller bioregions are a subset of larger bioregions and contribute significantly to the nestedness component of phylogenetic dissimilarity, here interpreted as evidence for a bioregional shift. We found a significant tendency of habitat shifts occurring preferentially between TRF and non-TRF bioregions (31 shifts) than from non-TRF to TRF (24) or from TRF to TRF (11) and non-TRF to non-TRF (9). Our results also present cases where low dissimilarity is found between TRF and non-TRF bioregions. Most bioregions showed phylogenetic clustering and larger bioregions tended to be more clustered than smaller ones, with a higher species turnover component of phylogenetic dissimilarity. However, phylogenetic structure did not differ between TRF and non-TRF bioregions and diversification rates were higher in only two lineages, Attaleinae and Bactridinae, which are widespread and overabundant in both TRF and non-TRF bioregions. Area and distance significantly affected Neotropical palm community assembly and contributed more than environmental variables. Despite palms being emblematic humid forest elements, we found multiple shifts from humid to dry bioregions, showing that palms are also important components of these environments.

Highlights

Short- and long-term ecological and evolutionary processes affect patterns of species composition and co-occurrence (Ricklefs, 2004)
Overall the species turnover component of phylogenetic dissimilarity was more frequent than the nestedness component (113 values above 0.6 threshold of turnover compared to 56 nestedness; Figures 2A,B and Table S6 in Appendix S4)
Our findings show that geographical variables such as area and adjacency play an important role in the assembly of Neotropical palm communities

Summary

Introduction

Short- and long-term ecological and evolutionary processes affect patterns of species composition and co-occurrence (Ricklefs, 2004). The restriction to particular ecological conditions may prevent lineages from habitat shifts and successful colonization of new areas (e.g., Wiens and Graham, 2005). Shifts indicate that lineages were able to colonize and persist in certain environments over time, leading to a nestedness pattern in phylogenetic beta diversity, i.e., the “sink” area is a subset of lineages from the “source” (Baselga, 2010; Leprieur et al, 2012). In situ diversification points to lineage diversification due to ecological opportunity to diversify and adapt, leading to a turnover pattern in phylogenetic beta diversity, i.e., phylogenetic dissimilarity will be due to exclusive lineages in each area (Baselga, 2010; Leprieur et al, 2012)

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Results

Conclusion