Genetic diversity of Cedrela fissilis (Meliaceae) in the Brazilian Atlantic Forest reveals a complex phylogeographic history driven by Quaternary climatic fluctuations

Abstract

Quaternary climatic fluctuations have shaped the geographic distribution of lineages, potentially affecting the demography, genetic structure, and patterns of genetic diversity of extant species. Different phylogeographic scenarios have been proposed for plants in neotropical cloud forests during the Last Glacial Maximum based on paleoecological data: the dry refugia hypothesis (DRH) and the moist forest hypothesis. We specifically focus on the Brazilian Atlantic Forest (BAF) range of Cedrela fissilis (Meliaceae), sampling 410 specimens from 50 localities. Our study combines analyses of the genetic diversity, phylogeographic patterns, and past geographic distributions with a particular focus on highland populations. We identified 283 alleles across the 11 microsatellite loci, ranging from 18 to 33 alleles per locus, distributed across five genetic groups. Most populations of C. fissilis from the BAF exhibited a diffuse genetic structure, reflected in low pairwise FST values, which could be the consequence of high gene flow. In addition, the plastid data showed a connection between the western, southern, and eastern populations in the North‐East of Brazil, but no association between genetic data and elevation was observed. Habitat suitability projections over the past 140 000 years showed less fragmentation relative to the present, indicating a higher connectivity and gene flow. Our results provide support for both the moist forest as well as the DRH, suggesting that most likely, a mixture of these processes has acted through space and time.

Biogeography of Neotropical Meliaceae: geological connections, fossil and molecular evidence revisited

“…Apart from the larger-scale geographic analyses mentioned above, several studies on selected single modern Neotropical Meliaceae species, or their complexes, have been conducted in the past two decades. Among these are the works by Cavers et al (2003Cavers et al ( , 2013 on Cedrela odorata L., by Mangaravite et al (2019) on C. fissilis Vell., and by Scotti-Saintagne et al ( 2013) on a species complex in Carapa. Cavers et al (2003) studied populations of Cedrela odorata in Central America, phylogenetically grouped into three lineages (northern, central and southern), and spatial analysis confirming a deviation from a pattern of isolation by distance.…”

EVALUATION OF DIVERSITY AND GENETIC STRUCTURE AS STRATEGIES FOR CONSERVATION OF NATURAL POPULATIONS OF Dalbergia nigra (Vell.) Allemão ex Benth.

“…The satisfactory levels found for the genetic diversity of the species indicate that it has managed to keep up with the disturbances generated by its predatory exploitation and the fragmentation of natural populations, having as a positive factor the fact that they are located in CU's, which restrict selective cutting. Studies with vulnerable and threatened species, such as D. nigra, demonstrated that these species can restore their population, if there is genetic diversity, knowledge and, control over the genetic structure in the occurrence areas (Martinelli and Moraes, 2013;Souza et al, 2017;Mangaravite et al, 2019). This is even more relevant because D. nigra is an allogamous species, that is, it preferably performs cross-fertilization benefited by entomophilous pollination, consequently increasing the genetic diversity.…”

Divergence in the Aquilegia ecalcarata complex is correlated with geography and climate oscillations: Evidence from plastid genome data

“…Quaternary glacial‐interglacial cycles have caused the migration of organisms and changed their spatial distribution patterns (Harrison et al, 2001; Hewitt, 2001; Liu & Manchester, 2019; Mangaravite et al, 2019). Organisms are also likely to die during these changes or to be preserved in refuges, later expanding from these refuges during the interglacial periods (Hewitt, 1996, 2001; Petit et al, 2003).…”