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Systematics, biogeography, and character evolution of Sparganium (Typhaceae): Diversification of a widespread, aquatic lineage
Author(s) -
Sulman Joshua D.,
Drew Bryan T.,
Drummond Chloe,
Hayasaka Eisuke,
Sytsma Kenneth J.
Publication year - 2013
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.1300048
Subject(s) - biology , character evolution , evolutionary biology , biogeography , coalescent theory , pantropical , systematics , lineage (genetic) , subgenus , genus , ecology , phylogenetics , clade , zoology , taxonomy (biology) , biochemistry , gene
• Premise of the study: Sparganium (Typhaceae) is a genus of aquatic monocots containing ±14 species, with flowers aggregated in unisexual, spherical heads, and habit ranging from floating to emergent. Sparganium presents an opportunity to investigate diversification, character evolution, and biogeographical relationships in a widespread temperate genus of aquatic monocots. We present a fossil‐calibrated, molecular phylogeny of Sparganium based on analysis of two chloroplast and two nuclear markers. Within this framework, we examine character evolution in both habit and stigma number and infer the ancestral area and biogeographic history of the genus. • Methods: Sequence data from two cpDNA and two nDNA markers were analyzed using maximum parsimony, maximum likelihood, and Bayesian inference. We used the program BEAST to simultaneously estimate phylogeny and divergence times, S‐DIVA and Lagrange for biogeographical reconstruction, and BayesTraits to examine locule number and habit evolution. • Key results: Two major clades were recovered with strong support: one composed of S. erectum and S. eurycarpum ; and the other containing all remaining Sparganium . We realigned the subgenera to conform to these clades. Divergence time analysis suggests a Miocene crown origin but Pliocene diversification. Importantly, the floating‐leaved habit has arisen multiple times in the genus, from emergent ancestors—contrary to past hypotheses. • Conclusions: Cooling trends during the Tertiary are correlated with the isolation of temperate Eurasian and North American taxa. Vicariance, long‐distance dispersal, and habitat specialization are proposed as mechanisms for Sparganium diversification.