Molecular phylogeny of Gymnocalycium (Cactaceae): Assessment of alternative infrageneric systems, a new subgenus, and trends in the evolution of the genus

Abstract

• Premise of the study: The South American genus Gymnocalycium (Cactoideae‐Trichocereae) demonstrates how the sole use of morphological data in Cactaceae results in conflicts in assessing phylogeny, constructing a taxonomic system, and analyzing trends in the evolution of the genus. • Methods: Molecular phylogenetic analysis was performed using parsimony and Bayesian methods on a 6195‐bp data matrix of plastid DNA sequences (atpI‐atpH, petL‐psbE, trnK‐matK, trnT‐trnL‐trnF) of 78 samples, including 52 species and infraspecific taxa representing all the subgenera of Gymnocalycium. We assessed morphological character evolution using likelihood methods to optimize characters on a Bayesian tree and to reconstruct possible ancestral states. • Key results: The results of the phylogenetic study confirm the monophyly of the genus, while supporting overall the available infrageneric classification based on seed morphology. Analysis showed the subgenera Microsemineum and Macrosemineum to be polyphyletic and paraphyletic. Analysis of morphological characters showed a tendency toward reduction of stem size, reduction in quantity and hardiness of spines, increment of seed size, development of napiform roots, and change from juicy and colorful fruits to dry and green fruits. • Conclusions: Gymnocalycium saglionis is the only species of Microsemineum and a new name is required to identify the clade including the remaining species of Microsemineum; we propose the name Scabrosemineum in agreement with seed morphology. Identifying morphological trends and environmental features allows for a better understanding of the events that might have influenced the diversification of the genus.

Flowering phenology, fruit set and seed mass and number of five coexisting Gymnocalycium (Cactaceae) species from Córdoba mountain, Argentina1

“…Nevertheless, our results showed inconsistent patterns as the species with larger seeds, G. bruchii and G. capillense, flowered at the beginning and at the end of the growing season, respectively. Since these species are closely related (belonging to the same subgenera; Demaio et al 2011) these results may indicate that seed mass in the species studied is highly conditioned by other factors associated with the evolutionary history of these species and not by ecological factors related to seasonality. The close relationship between seed characteristics and taxonomy in the genus Gymnocalycium was suggested in traditional botanical studies many years ago (e.g., Kreuzinger 1935, Buxbaum 1968) and is highly supported by molecular studies more recently (Meregalli, Ercole, andRodda 2010, Demaio et al 2011).…”

Insights into chloroplast genome variation across Opuntioideae (Cactaceae)

“…Apart from the external and internal transcribed spacer (ETS and ITS) of the nuclear ribosomal repeats (NRR) and ppc marker, most molecular phylogenies of cacti have been historically based on few plastid markers (trnL-trnF, rpl16, trnK and matK) (Nyffeler 2002;Edwards et al 2005;Korotova et al 2010;Demaio et al 2011;Arakaki et al 2011;Bárcenas et al 2011;Hernández-Hernández et al 2011;Hernández-Hernández et al 2014;Ritz et al 2012;Bárcenas 2016;Luna-Vargas et al 2018). While these markers have shown to be potentially able to resolve some clades, some relationships are still lacking support (Nyffeler 2002;Griffiths & Porter 2009;Hernández-Hernández et al 2011;Bárcenas et al 2011).…”

“…;Korotova et al 2010;Demaio et al 2011;Arakaki et al 2011;Bárcenas et al 2011;Hernández-Hernández et al 2011;Hernández-Hernández et al 2014;Ritz et al 2012;Bárcenas 2016;Luna-Vargas et al 2018); whileMajure et al (2012) has used partial sequences of the ycf1 gene. The others top 10 markers have been previously used under phylogenomic approaches in cacti(Arakaki et al 2011;Majure et al 2019).Although the majority of the top 10 markers here reported have not been used in phylogenetic studies of cacti, the relationship of several other groups has been inferred with some of these markers.…”

A molecular phylogenetic approach to the systematics of Cylindropuntieae (Opuntioideae, Cactaceae)

“…Demaio et al. () reconstructed phylogenetic relationships of Gymnocalycium using four plastid regions and tested the current subgeneric classification of the genus largely based on seed morphology. Franck et al.…”

“…However, they were able to identify indel events that were characteristic for the M. crinita group in their rpl16 intron data set. Demaio et al (2011) reconstructed phylogenetic relationships of Gymnocalycium using four plastid regions and tested the current subgeneric classification of the genus largely based on seed morphology. Franck et al (2013) used plastid and nuclear markers to reconstruct the phylogeny of Harrisia recovering a monophyletic genus consisting of 20 species.…”