Selective Sweeps Lead to Evolutionary Success in an Amazonian Hyperdominant Palm

Abstract

Despite the global importance of tropical ecosystems, few studies have identified how natural selection has shaped their megadiversity. Here, we test for the role of adaptation in the evolutionary success of the widespread, highly abundant Neotropical palm Mauritia flexuosa. We used a genome scan framework, sampling 16,262 single-nucleotide polymorphisms (SNPs) with target sequence capture in 264 individuals from 22 populations in rainforest and savanna ecosystems. We identified outlier loci as well as signal of adaptation using Bayesian correlations of allele frequency with environmental variables and detected both selective sweeps and genetic hitchhiking events. Functional annotation of SNPs with selection footprints identified loci affecting genes related to adaptation to environmental stress, plant development, and primary metabolic processes. The strong differences in climatic and soil variables between ecosystems matched the high differentiation and low admixture in population Bayesian clustering. Further, we found only small differences in allele frequency distribution in loci putatively under selection among widespread populations from different ecosystems, with fixation of a single allele in most populations. Taken together, our results indicate that adaptive selective sweeps related to environmental stress shaped the spatial pattern of genetic diversity in M. flexuosa, leading to high similarity in allele frequency among populations from different ecosystems.

The origin of modern patterns of continental diversity in Mauritiinae palms: the Neotropical museum and the Afrotropical graveyard

“…At some point, however, the evolutionary history of Mauritiinae on the different continents diverged, as Mauritiinae are nowadays only found in the Neotropical region, where five extant species are recognized. Not only did the group survive in the Neotropics but one species, Mauritia flexuosa became one of the most dominant tree species in Amazonia, with ca 1.5 billion individuals [12,13].…”

Genetic structure, phylogeography, adaptive variation and speciation in the tropical tree genus Symphonia

“…These difficulties have slowed down the pace in evolutionary research in tropical tree species, an understudied group of trees yet the most diverse, compared to the more accessible boreal and temperate species (Neale & Kremer, 2011;Fetter, Gugger, & Keller, 2017). For example, research on local adaptation, especially at large scales, has advanced faster in boreal and temperate species (e.g., Eckert & Dyer, 2012;Parchman et al, 2012;Alberto et al, 2013), although research on tropical species is increasingly making progress (e.g., Collevatti et al, 2019;Melo, Vieira, Novaes, Bacon, & Collevatti, 2020;Brousseau, Fine, Dreyer, Vendramin, & Scotti, 2021).…”