Phylogeny of a Neotropical Clade in the Gesneriaceae: More Tales of Convergent Evolution

Abstract

The Gesneriaceae is a family known for convergent evolution of complex floral forms. As a result, defining genera and resolving evolutionary relationships among such genera using morphological data alone has been challenging and often does not accurately reflect monophyletic lineages. The tribe Episcieae is the most diverse within Neotropical Gesneriaceae in terms of its number of species and morphological diversity. As a result, defining genera using floral characters has been historically troublesome. Here we investigate relationships among genera of the tribe using an array of chloroplast DNA, nuclear ribosomal genes, and low-copy nuclear genes to provide resolution for the monophyly of the genera and relationships among the monophyletic groups. All known genera in the tribe (with the exception of the monospecific Lampadaria) have been sampled, and most have been sampled to provide an assessment to determine their monophyly. Of the 17 genera in the tribe that comprise more than a single species, we have sampled 15 with at least two species. The following six genera are identified as para-or polyphyletic: Neomortonia, Episcia, Paradrymonia, Nautilocalyx, Codonanthe, and Nematanthus. Our results strongly support at least three independent origins of fleshy fruits, which are defined here as fleshy display capsules or indehiscent berries.

Independent evolution of pouched flowers in the Amazon is supported by the discovery of a new species of Lesia (Gesneriaceae) from Serra do Aracá tepui in Brazil

“…When compared to Gesneriaceae species occurring in the Amazon and Guyana shield, these specimens from Serra do Aracá share some similarities in habit and flower morphology with the genus Lesia J.L.Clark & J.F.Sm., which has been recently segregated from Nematanthus, based on phylogenetic evidence (Smith and Clark 2013). As currently defined Lesia comprises a single species, Lesia savannarum that occurs in rain forests at low and medium elevation along a periAmazonian arc from the Andes foothills in eastern Peru to Colombia, northern Brazil (Amazonas and Roraima) and the Guyana Shield (Skog and Feuillet 2008;Smith and Clark 2013 (Clark et al 2006(Clark et al , 2012Chautems and Perret 2013). A better resolution of the relationships among these morphologically distinct taxa is, however, needed to further explore how flower and biogeographic distribution have evolved in this clade.…”

Pollen morphology in Brazilian species of Codonanthe (Mart.) Hanst. and Nematanthus Schrader (Gesneriaceae)

“…Based on molecular phylogenetic studies, Clark et al (2006Clark et al ( , 2012 and Perret et al (2013) reported the close relationship of Nematanthus australis Chautems and N. wettsteinii to the genus Codonanthe, with both species nesting within Codonanthe. Through pollen grains observations of N. wettsteinii, it was found that the pollen morphology supported such a placement.…”

“…and Nematanthus Schrader] and by the presence of sepals connate at the base and an urceolate cup or funnel-shaped calyx (Wiehler, 1983;Clark et al, 2006). Molecular data shows that the tribe represents a monophyletic clade with a heterogeneous morphology within the Gesneriaceae (Smith & Carroll, 1997;Smith, 2000aSmith, , 2000bZimmer et al, 2002;Clark et al, 2006Clark et al, , 2012.…”

Besleria macropoda (Gesneriaceae): lectotypification, distribution, functional epiphylly and discordant fruit morphology of a rare Costa Rican endemic

“…Display capsules and their contrasting color effects are assumed to attract seed dispersing animals in Drymonia and related genera (Wiehler 1983, Weber 2004, 2012. For the fleshy and irregularly dehiscent capsules of Solenophora calycosa Donnell Smith (1898: 152), Weber & Weissenhofer (2007) suggested that the contrast provided by the fruit wall (orange) and the placentae plus seeds (deep red) is attractive to birds and/or small mammals.…”