Early Diverging and Core Bromelioideae (Bromeliaceae) Reveal Contrasting Patterns of Genome Size Evolution and Polyploidy

Abstract

The subfamily Bromelioideae is one of the most diverse groups among the neotropical Bromeliaceae. Previously, key innovations have been identified which account for the extraordinary radiation and species richness of this subfamily, especially in the so-called core Bromelioideae. However, in order to extend our understanding of the evolutionary mechanisms, the genomic mechanisms (e.g. polyploidy, dysploidy) that potentially underlie this accelerated speciation also need to be tested. Here, using PI and DAPI staining and flow cytometry we estimated genome size and GC content of 231 plants covering 30 genera and 165 species and combined it with published data. The evolutionary and ecological significance of all three genomic characters was tested within a previously generated dated phylogenetic framework using ancestral state reconstructions, comparative phylogenetic methods, and multiple regressions with climatic variables. The absolute genome size (2C) of Bromelioideae varied between 0.59 and 4.11 pg, and the GC content ranged between 36.73 and 41.43%. The monoploid genome sizes (Cx) differed significantly between core and early diverging lineages. The occurrence of dysploidy and polyploidy was, with few exceptions, limited to the phylogenetically isolated early diverging tank-less lineages. For Cx and GC content Ornstein-Uhlenbeck models outperformed the Brownian motion models suggesting adaptive potential linked to the temperature conditions. 2C-values revealed different rates of evolution in core and early diverging lineages also related to climatic conditions. Our results suggest that polyploidy is not associated with higher net diversification and fast radiation in core bromelioids. On the other hand, although coupled with higher extinction rates, dysploidy, polyploidy, and resulting genomic reorganizations might have played a role in the survival of the early diverging bromelioids in hot and arid environments.

Repeat proliferation and partial endoreplication jointly shape the patterns of genome size evolution in orchids

“…Recently, evidence that nDNA content variation has adaptive significance for angiosperms has sparked efforts to better understand the mechanisms driving genome size evolution in plants (Bilinski et al ., 2018; Carta and Peruzzi, 2016; Paule et al ., 2020; Pellicer et al ., 2018). Ideally, such investigations should include phylogenetic comparative analyses, because they are statistically more appropriate than ordinary models and allow to elucidate the patterns and tempo of genome size evolution as well as to explore its potential causes and consequences (e.g., Du et al ., 2017; Mandák et al ., 2016; Qiu et al ., 2019).…”

Genome size variation and whole-genome duplications in the monocot order Poales

“…specimen was obviously diploid, which means that the previously studied Quesnelia Gaudich. species with twice as high 2C values(Paule et al 2020) were in fact tetraploid and not diploid as assumed.Cyperaceae. Ten of the eleven Cyperaceae species studied had low 2C values between 0.54 pg (Bolboschoenus laticarpus Marhold, Hroudová, Ducháček & Zákr.)…”

Target‐enrichment sequencing reveals for the first time a well‐resolved phylogeny of the core Bromelioideae (family Bromeliaceae)

“…), and in dry tropical conditions ( Bromelia L., Deinacanthon Mez, Cryptanthoid complex). However, the center of Bromelioideae species diversity is the Atlantic rainforest of Brazil (Zizka & al., 2020), where the subfamily underwent rapid speciation, and species almost exclusively are characterized by tank habit, diploidy, and CAM photosynthesis (so called “core Bromelioideae”; Gitaí & al., 2014; Silvestro & al., 2014; Crayn & al., 2015; Paule & al., 2020a).…”