Coalescent Simulation and Paleodistribution Modeling for Tabebuia rosealba Do Not Support South American Dry Forest Refugia Hypothesis

• Published in: PloS one Vol. 11; no. 7; p. e0159314
• Main Authors: de Melo, Warita Alves, Lima-Ribeiro, Matheus S., Terribile, Levi Carina, Collevatti, Rosane G.
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 26.07.2016; Public Library of Science (PLoS)
• Subjects: Aridity; Bignoniaceae; Biodiversity; Biological diversity; Biology and Life Sciences; Brazil; Chloroplast membrane; Climate change; Climatic conditions; Coalescence; Coalescing; Computer simulation; Current distribution; Demographics; Demography; Dry forests; Earth Sciences; Ecological niches; Ecology; Ecology and Environmental Sciences; Ecosystems; Forest refugia; Forests; Fossils; Fragmentation; Genetic diversity; Genetic Variation; Genetics, Population; Genomes; Geographical distribution; Geography; Grasslands; Hypotheses; Last Glacial Maximum; Modelling; Models, Statistical; Models, Theoretical; Niches (Ecology); People and Places; Phylogeny; Phylogeography; Physiological aspects; Pleistocene; Pollen; Population (statistical); Refugia; Refugium; River basins; Seasonal distribution; Seasons; Sequence Analysis, DNA; Spatial Analysis; Spatial discrimination; Spatial distribution; Tabebuia; Tabebuia - classification; Tabebuia - genetics; Trends; Tropical Climate; Tropical forests; South America; Brazil; Cerrado Biome; New York; Bolivia; United States > US
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0159314

Studies based on contemporary plant occurrences and pollen fossil records have proposed that the current disjunct distribution of seasonally dry tropical forests (SDTFs) across South America is the result of fragmentation of a formerly widespread and continuously distributed dry forest during the arid climatic conditions associated with the Last Glacial Maximum (LGM), which is known as the modern-day dry forest refugia hypothesis. We studied the demographic history of Tabebuia rosealba (Bignoniaceae) to understand the disjunct geographic distribution of South American SDTFs based on statistical phylogeography and ecological niche modeling (ENM). We specifically tested the dry forest refugia hypothesis; i.e., if the multiple and isolated patches of SDTFs are current climatic relicts of a widespread and continuously distributed dry forest during the LGM. We sampled 235 individuals across 18 populations in Central Brazil and analyzed the polymorphisms at chloroplast (trnS-trnG, psbA-trnH and ycf6-trnC intergenic spacers) and nuclear (ITS nrDNA) genomes. We performed coalescence simulations of alternative hypotheses under demographic expectations from two a priori biogeographic hypotheses (1. the Pleistocene Arc hypothesis and, 2. a range shift to Amazon Basin) and other two demographic expectances predicted by ENMs (3. expansion throughout the Neotropical South America, including Amazon Basin, and 4. retraction during the LGM). Phylogenetic analyses based on median-joining network showed haplotype sharing among populations with evidence of incomplete lineage sorting. Coalescent analyses showed smaller effective population sizes for T. roseoalba during the LGM compared to the present-day. Simulations and ENM also showed that its current spatial pattern of genetic diversity is most likely due to a scenario of range retraction during the LGM instead of the fragmentation from a once extensive and largely contiguous SDTF across South America, not supporting the South American dry forest refugia hypothesis.