Author's personal copy Molecular phylogenetic relationships and the coevolution of placentotrophy and superfetation in Poecilia (Poeciliidae: Cyprinodontiformes) Robert W. Meredith ⇑ , Marcelo N. Pires, David N. Reznick, Mark S. Springer ⇑ Department of Biology, University of California, Riverside, CA 92521, USA article info Article history: Received 26 July 2010 Revised 18 January 2011 Accepted 27 January 2011 Available online 1 February 2011 Keywords: Cyprinodontiformes Poeciliidae Pamphorichthys Poecilia Correlated evolution Placentotrophy Superfetation abstract Members of Poeciliidae are used as model organisms for experimental studies on natural and sexual selection, and comparative studies of life-history evolution. The latter have demonstrated multiple ori- gins of both superfetation and placentotrophy within Poeciliidae. Most recently, placentotrophy has been described in five species of Poecilia (Pamphorichthys), but only one of these (P. hasemani) shows evidence of superfetation. Here, we use a molecular phylogeny based on concatenated nuclear and mitochondrial gene sequences to test hypotheses of correlated evolution between superfetation and placentotrophy in Poecilia. Taxon sampling included all species in the subgenera Micropoecilia and Pamphorichthys for which the presence or absence of placentotrophy and superfetation have been determined, as well as represen- tatives of all other Poecilia subgenera (Acanthophacelus, Limia, Mollienesia, Poecilia, Pseudolimia). Phyloge- netic analyses were performed with maximum parsimony, maximum likelihood, and Bayesian methods; ancestral states for life-history characters were reconstructed with parsimony and SIMMAP; correlation analyses were performed with SIMMAP; and divergence times were estimated using a relaxed molecular clock. All subgenera in Poecilia were recovered as monophyletic. The basal split in Poecilia is between P. (Acanthophacelus)+ P.(Micropoecilia) and the other five subgenera. In the latter clade, P.(Poecilia) is the sister-group to the remaining four subgenera. Within P. (Pamphorichthys), all analyses with the combined data set recovered P. (Pamphorichthys) araguaiensis as the sister taxon to P.(Pamphorichthys) hollandi, and P.(Pamphorichthys) scalpridens as the sister taxon to P.(Pamphorichthys) minor. P.(Pamphorichthys) hase- mani was either the sister taxon to P.(Pamphorichthys) hollandi + P.(Pamphorichthys) minor (maximum likelihood, Bayesian) or the sister taxon to all other Pamphorichthys species (maximum parsimony). Ancestral state reconstructions suggest that placentotrophy and superfetation evolved on the same branch in P.(Micropoecilia), whereas placentotrophy evolved before superfetation in P.(Pamphorichthys). SIMMAP analyses indicate a statistically significant association between placentotrophy and superfeta- tion. Within P. (Micropoecilia) both placentotrophy and superfetation evolved in 64 million years. Within P.(Pamphorichthys), superfetation evolved in 69 million years on the P.(Pamphorichthys) hasemani branch, and placentotrophy evolved in 610 million years in the common ancestor of this subgenus. Ó 2011 Elsevier Inc. All rights reserved. 1. Introduction 1.1. General background The endemic New World cyprinodontiform family Poeciliidae (Rosen and Bailey, 1963: Poeciliinae sensu Parenti, 1981) is com- posed of 220 species in 28 genera (Lucinda, 2003; Lucinda and Reis, 2005). All poeciliid fishes are characterized by the presence of a gonopodium (modified anal-fin rays 3, 4, and 5; Hubbs, 1924; Lucinda and Reis, 2005) and internal fertilization, and all but Tomeurus are viviparous (Regan, 1913; Rosen and Gordon, 1953; Rosen and Bailey, 1963). Members of this family are commonly found in the pet trade (e.g., swordtails, guppies, and mollies) and are model organisms for experimental studies on nat- ural and sexual selection (Endler, 1983; Houde, 1997; Schluter et al., 1998; Hamilton, 2001). Comparative studies on life-history evolution in Poeciliidae have demonstrated multiple origins of superfetation (the ability to carry multiple broods at different developmental stages) and placentotrophy (the post-fertilization provisioning of developing embryos by the mother through a placenta) (Grove and Wourms, 1991, 1994; Arias and Reznick, 2000; Reznick et al., 2002, 2007; Pires, 2007; Meredith et al., 2010; Pires et al., 2010). In Poecilia, placentotrophy and superfeta- tion evolved once in the subgenus Micropoecilia in the common ancestor of P. bifurca, P. branneri, and P. parae (Meredith et al., 2010; Pires et al., 2010). More recently, Pires and Reznick (submitted for publication) reported placentotrophy in all species of Poecilia (Pamphorichthys) that were investigated, whereas 1055-7903/$ - see front matter Ó 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.ympev.2011.01.014 ⇑ Corresponding authors. Fax: +1 909 787 4826. E-mail addresses: robert.meredith@email.ucr.edu (R.W. Meredith), mark.sprin- ger@ucr.edu (M.S. Springer). Molecular Phylogenetics and Evolution 59 (2011) 148–157 Contents lists available at ScienceDirect Molecular Phylogenetics and Evolution journal homepage: www.elsevier.com/locate/ympev