Unraveling the Spiraling Radiation: A Phylogenomic Analysis of Neotropical Costus L

Abstract

The family of pantropical spiral gingers (Costaceae Nakai; c. 125 spp.) can be used as a model to enhance our understanding of the mechanisms underlying Neotropical diversity. Costaceae has higher taxonomic diversity in South and Central America (c. 72 Neotropical species, c. 30 African, c. 23 Southeast Asian), particularly due to a radiation of Neotropical species of the genus Costus L. (c. 57 spp.). However, a well-supported phylogeny of the Neotropical spiral gingers including thorough sampling of proposed species encompassing their full morphologic and geographic variation is lacking, partly due to poor resolution recovered in previous analyses using a small sampling of loci. Here we use a phylogenomic approach to estimate the phylogeny of a sample of Neotropical Costus species using a targeted enrichment approach. Baits were designed to capture conserved elements' variable at the species level using available genomic sequences of Costus species and relatives. We obtained 832 loci (generating 791,954 aligned base pairs and 31,142 parsimony informative sites) for samples that encompassed the geographical and/or morphological diversity of some recognized species. Higher support values that improve the results of previous studies were obtained when including all the available loci, even those producing unresolved gene trees and having a low proportion of variable sites. Concatenation and coalescent-based species trees methods converge in almost the same topology suggesting a robust estimation of the relationships, even under the high levels of gene tree conflict presented here. The bait set design here presented made inferring a robust phylogeny to test taxonomic hypotheses possible and will improve our understanding of the origins of the charismatic diversity of the Neotropical spiral gingers.

Parahellenia, a new genus segregated from Hellenia (Costaceae) based on phylogenetic and morphological evidence

“…Costaceae Nakai, commonly known as the spiral ginger family, is a small family of Zingiberales and easily distinguished from other families within the order by well-developed and sometimes branched aerial shoots that have a characteristic spiral phyllotaxy, tubular leaf sheaths and petaloid labellum formed by fusion of five sterile staminodes ( Kirchoff and Ruitshauser, 1990 ; Kress, 1990 ; Kress et al., 2001 ; Larsen, 1998 ; Wu and Larsen, 2000 ; Specht and Stevenson, 2006 ). It consists of seven genera and more than 120 species, pantropically distributed with species abundant in the Neotropics ( Specht, 2006a ; André et al., 2016 ; van Caspel, 2019 ; Valderrama et al., 2020 ). Previous phylogenetic analyses of the family Costaceae based on multiple molecular marks from chloroplast ( trn K intron and trn L-F spacer) regions and nuclear ribosomal internal transcribed spacer region (ITS) as well as morphological and biogeographic information recognized three major lineages: a South American clade (consisting of Chamaeocostus C.D.…”

“…However, the relationships remained unresolved for some clades, notably the Asian and Costus clades. Recent phylogenetic studies have mainly focused on the Costus clade (see Kay et al., 2005 ; Salzman et al., 2015 ; André et al., 2016 ; Maas-van de Kamer et al., 2016 ; Valderrama et al., 2020 ) while few studies have so far been conducted on phylogenetic relationships within the Asian clade. Within this clade, Paracostus and Tapeinochilos were supported as distinct monophyletic groups ( Specht et al., 2001 ; Specht, 2006a , 2006b ; André et al., 2016 ; Carlsen et al., 2018 ), but the relationships among the remaining members are uncertain, in particularly, the genus Cheilocostus (≡ Hellenia Retz.).…”

The genetic mechanisms underlying the convergent evolution of pollination syndromes in the Neotropical radiation of Costus L.

“…Mellitophilous flowers are most often subtended by green, often leafy, bracts while ornithophilous flowers are subtended by bright red, orange, or yellow bracts. Previous phylogenetic studies have estimated multiple shifts in pollination syndromes during the evolution of Neotropical Costus , including shifts to mellitophilous pollination syndromes and subsequent regains of ornithophilous flowers ( Specht, 2006 ; Salzman et al, 2015 ; Valderrama et al, 2020 ; Vargas et al, 2020 ), mainly through sympatric speciation events ( André et al, 2016 ). These results suggest that shifts in traits leading to distinct pollination syndromes, together with reproductive isolation via reinforcement, may account for the rapid radiation observed in this Neotropical clade.…”

MORFOLOGIA DE Costus spiralis (JACQ.) ROSCOE (COSTACEAE): UMA ESPÉCIE MEDICINAL EM ALTA FLORESTA, MATO GROSSO

“…A família Costaceae Nakai (Zingiberales) possui distribuição pantropical e está representada pelos gêneros Cheilocostus C. Specht, Chamaecostus C. Specht & D. W. Stevenson, Costus L., Dimerocostus O. Kuntze, Monocostus K. Schumann, Paracostus C. Specht e Tapeinochilos Miquel (STEVENS, 2021; WFO, 2021), totalizando 125 espécies distribuídas pelo mundo, com centros de diversidade na região neotropical, com 72 espécies, no continente africano, com 30 espécies, e na região sudeste da Ásia, com 23 espécies (VALDERRAMA et al, 2020).…”

“…O gênero Costus está representado na região neotropical por 57 espécies, considerado o principal gênero da família (VALDERRAMA et al, 2020). No Brasil, possui 15 espécies, quase todas na Amazônia, com 14 espécies, os outros domínios fitogeográficos estão entre duas ou três espécies, exceto o Pampa que até o momento não tem nenhum registro de ocorrência; o estado de Mato Grosso está representado por seis espécies do gênero (ANDRÉ, 2020).…”