Phylogenetics of the florally diverse Andean clade Iochrominae (Solanaceae)

Abstract

Recent molecular phylogenetic studies of Solanaceae have identified many well-supported clades within the family and have permitted the creation of a phylogenetic system of classification. Here we estimate the phylogeny for Iochrominae, a clade of Physaleae sensu Olmstead et al. (1999), which contains 34 Andean species encompassing an immense diversity of floral forms and colors. Using three nuclear regions, ITS, the second intron of LEAFY, and exons 2 to 9 of the granule-bound starch synthase gene (waxy), we evaluated the monophyly of the traditional genera comprising Iochrominae and assessed the extent of interspecific hybridization within the clade. Only one of the six traditionally recognized genera of Iochrominae was supported as monophyletic. Further, comparison of the individual nuclear data sets revealed two interspecific hybrid taxa and a third possible case. These hybrid taxa occur in the Amotape-Huancabamba zone, a region between the northern and central Andes that has the greatest diversity of Iochroma species and offers frequent opportunities for hybridization in areas of sympatry. We postulate that periodic hybridization events in this area coupled with pollinator-mediated selection and the potential for microallopatry may have acted together to promote diversification in montane Andean taxa, such as Iochrominae.

Phylogeny of Nolana (Solanaceae) of the Atacama and Peruvian deserts inferred from sequences of four plastid markers and the nuclear LEAFY second intron

“…In Solanaceae, initial phylogenetic studies detected 29 only one copy of the GBSSI gene, such as in the diploid Solanum (Levin et al, 2006; 30 Peralta and Spooner, 2001), the Iochrominae group of the tribe Physaleae (Smith and Baum, 2006), Schizanthus (Perez et al, 2006), and Nolana's close 1 relative Lycieae (Levin and Miller, 2005). In a recent study, more than two copies of 2 this gene were found in Hyoscyameae, a polyploid group from the northern hemisphere 3 closely related to Nolana (Yuan et al, 2006).…”

“…The first use of LEAFY for phylogenetic study of Solanaceae 13 (Smith and Baum, 2006) All 63 species analyzed in our previous GBSSI study (Dillon et al 2007) followed Olmstead and Sweere (1994), Shaw et al (2005) and Shaw et al (2007), 13 respectively. The primers trnC (5'-CCAGTTCAAATCCGGGTGTC-3') and 2039R…”

Systematics of Iochrominae (Solanaceae): Patterns in Floral Diversity and Interspecific Crossability

“…Combined phylogenetic analyses from three nuclear loci, the internal transcribed spacer (ITS), the second intron of LEAFY, and exons 2 to 9 of GBSSI, show that all of the traditional genera, with the exception of Vassobia and the monotypic Acnistus, are not monophyletic (Figure 1; Smith and Baum, 2006). Accordingly, many of the floral characters used to delimit groups appear to be homoplasious.…”

“…This paper focuses on Iochrominae sensu Olmstead et al (1999), a group of Andean Solanaceae whose evolutionary history has recently been clarified using DNA sequence data from three nuclear regions (Smith and Baum, 2006). Using this phylogenetic framework, we here examine the evolution of taxonomically important floral traits and evaluate the potential for hybridization among species distributed across the clade.…”

“…The occurrence of hybridization in the wild has long been noted by collectors and taxonomists (Shaw, 1998;Smith, 2006). Smith and Baum (2006) identified three putative hybrid taxa based on morphological features, geographic distribution, and conflicting position in nuclear gene phylogenies. In each instance, parental taxa were not each other's closest relatives, suggesting wide crossability among members of Iochrominae.…”