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Phylogenetic patterns of diversification in the Beslerieae (Gesneriaceae)

Authors:
  • Lawrenceville School

Abstract

Tribe Beslerieae constitute one of eight tribes currently recognized in Gesneriaceae subfamily Gesnerioideae and is currently considered to include seven genera: Anetanthus, Besleria, Cremosperma, Gasteranthus, Reldia, Resia, and Tylopsacas. Here we explore phylogenetic relationships among the major genera of Beslerieae, Besleria, Cremosperma, Gasteranthus, and Reldia, using nrDNA ITS sequences to explore generic monophyly, previous classification and phylogenetic hypotheses, and patterns of fruit-type evolution, stomatal cluster evolution, and biogeography. ITS data supports the monophyly of Besleria, Cremosperma, Gasteranthus, and Reldia, the intermediate position of fleshy capsules in the transformation of dry capsules to irregularly splitting or indehiscent berries, a single loss of stomatal clusters in the Beslerieae, and complex biogeographic patterns in the tribe but likely a single origin of Caribbean Besleria originating from northeastern South America.
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... The neotropical genus Besleria Linnaeus (1753b: 619) comprises an estimated number of 200+ species, with centers of diversity in the Andes of Colombia and Ecuador. It is the type genus of the monophyletic (but morphologically heterogeneous) tribe Beslerieae within the subfamily Gesnerioideae (Roalson & Clark 2006, Clark et al. 2010, Weber et al. 2013. A remarkable flower and fruit diversity is found within the Beslerieae which has led to confusion on the circumscription of some genera included therein. ...
... The genus Besleria was last revised by Morton (1939) who used an overly broad generic concept that included Gasteranthus Bentham (1846: 233), which was later segregated from Besleria based on an improved understanding of fruit characters (Wiehler 1975, Skog & Kvist 2000. Subsequent generic circumscriptions within the tribe have been confirmed by phylogenetic studies (Smith 2000, Roalson & Clark 2006, Clark et al. 2010. Nevertheless, the genus is in need of a modern revision and much work remains to be done, especially concerning the circumscription of currently recognized species and the description of many new species. ...
... This study strongly supports that fruit morphology in Besleria is less uniform than previously reported. It should be noted that the terms "peeling/rupturing berries" as used by Wiehler (1983) or Roalson & Clark (2006) are self-contradictory from a strictly morphological point of view: by definition, berries are indehiscent fruits, while the terms legume, follicle (both unicarpellate) and capsule (bi-or pluricarpellate) are tied to dehiscing fruits. However, there is preliminary evidence from ITS sequence data that two species with rupturing dehiscence, B. pendula and B. variabilis, are nested at different positions within the bulk of species having typical (indehiscent) berries (Roalson & Clark 2006). ...
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Besleria macropoda, a rare and poorly known gesneriad endemic to Costa Rica, was recently collected for the first time on the southern slopes of the Fila Costeña (Puntarenas Province, SE Costa Rica). The collection considerably widens the geographic distribution to the southeastern part of Costa Rica. Moreover, the following unique characters not previously addressed in the literature were observed and are documented here: (1) The elongate peduncles of the inflorescences are clamped in a channel formed by the sunken midrib of the leaf, rendering the flowers and fruits positioned in the center of the leaf blade. The epiphyllous appearance of the inflorescence on the leaf surface enhances contrasting colors that may aid the pollination and/or fruit dispersal. (2) The fruits split open irregularly, with the fleshy carpel lobes becoming reflexed. This fruit dehiscence deviates from the indehiscent berries that typically characterize Besleria. This results in displaying a globose head of red placental tissue covered by tiny, red seeds. A preliminary survey of Besleria fruits suggests that this peculiar fruit type is present in at least 15 species representing almost 8% of the genus. Fruit morphology of Besleria is therefore less uniform than previously recognized and the “indehiscent berry” can no longer serve as a distinctive generic character of Besleria, which necessitates consideration in floras and identification keys. In addition, a list of herbarium specimens, lectotypification, a distribution map, IUCN red list assessment and an amended key to diagnose Besleria relative to Gasteranthus are provided.
... Clark et al. (2008Clark et al. ( , 2009) included samples of 70 species of Cyrtandra, though the genus is huge (652-818 species, Atkins et al. 2013) and sampling density is under 10%. A similar level of sampling was achieved by Roalson and Clark (2006) for the large New World genus Besleria L. (ca. 22 out of 165+). ...
... 22 out of 165+). In the same study (Roalson & Clark 2006) there were 19 out of 35 species (over 50%) analyzed in Gasteranthus Benth. Roalson et al. (2003) included all 24 species of Achimenes Pers. ...
... Generic relationships within Beslerieae show partly different topologies between the studies by Smith (2000a) and Roalson and Clark (2006) and Clark et al. (2010), though for the first many intergeneric branches receive no or low support, and the topology of the latter studies is presented (FIGURE 2A). The relationships between Gasteranthus and Reldia Wiehler are in conflict between Clark et al. (2010) and Roalson and Clark (2006), or less resolved in the latter, though this study included only four Beslerieae genera. ...
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Sparked by the publication of large phylogenetic studies and major generic redefinitions in the Gesneriaceae, we review this growing body of molecular studies on the family. Different aspects of molecular data and their use in Gesneriaceae systematics are considered including conceptual challenges on the phylogenetic work undertaken to date as well as an overview of taxon sampling in the family. Molecular data are currently available for 70 of 72 recognized New World genera and 64 of 68 Old World genera. Many of the smaller genera and some of the larger genera are completely sampled. Current knowledge of tribal and generic delineations and relationships among the New World genera is relatively advanced. In contrast, intergeneric relationships and tribal arrangements are mostly unresolved for the Old World genera. In this paper we illustrate and summarize the published phylogenetic work in composite phylogenies with an emphasis on the most pertinent and accurate molecular systematic studies. This paper provides the molecular-based background for a new formal classification of the family Gesneriaceae.
... The subfamilies and tribes of Gesneriaceae have been the focus of many targeted phylogenetic analyses; hence, there are many available sequences from Gesneriaceae taxa (Atkins et al. 2001;Zimmer et al. 2002;Roalson et al. 2005Roalson et al. , 2008Clark et al. 2006Clark et al. , 2009Clark et al. , 2011Clark et al. , 2012Roalson and Clark 2006;Perret et al. 2007Perret et al. , 2013Möller et al. 2009Möller et al. , 2011Wang et al. 2010;Puglisi et al. 2011;Weber et al. 2011;Woo et al. 2011;Smith and Clark 2013; among others, for a review see Möller and Clark 2013). To investigate phylogenetic relationships in Gesneriaceae, we used PhyLoTA (Sanderson et al. 2008) to assemble a data set of nucleotide sequences available from GenBank release 194.0 (Supplementary Appendix 1, available on Dryad at http://dx.doi.org/10.5061/dryad.1br13). ...
... Core Beslerieae are inferred to have an elevated speciation rate over background rates (0.6466491 vs. 0.2183877), and also a significantly elevated extinction rate relative to background (0.3916895 vs. 0.0584205; Table 2; Fig. 3). This clade demonstrates interesting variation in growth form from small rosette plants to moderate-sized shrubs, and substantial variation in floral form (Wiehler 1975;Skog and Kvist 2000;Roalson and Clark 2006). The inferred high speciation rate in this clade is contrary to the expectation for generally woody lineages which are typically found to have fewer species, and slower diversification rates, than herbaceous lineages (Ricklefs and Renner 1994;Dodd et al. 1999;Smith and Donoghue 2008;. ...
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Using a time-calibrated phylogenetic hypothesis including 768 Gesneriaceae species (out of ~ 3300 species) and more than 29,000 aligned bases from 26 gene regions, we test Gesneriaceae for diversification rate shifts and the possible proximal drivers of these shifts: geographic distributions, growth forms, and pollination syndromes. Bayesian Analysis of Macroevolutionary Mixtures analyses found five significant rate shifts in Beslerieae, core Nematanthus , core Columneinae, core Streptocarpus , and Pacific Cyrtandra . These rate shifts correspond with shifts in diversification rates, as inferred by Binary State Speciation and Extinction Model and Geographic State Speciation and Extinction model, associated with hummingbird pollination, epiphytism, unifoliate growth, and geographic area. Our results suggest that diversification processes are extremely variable across Gesneriaceae clades with different combinations of characters influencing diversification rates in different clades. Diversification patterns between New and Old World lineages show dramatic differences, suggesting that the processes of diversification in Gesneriaceae are very different in these two geographic regions.
... Gasteranthus is a genus of terrestrial herbs and subshrubs that ranges from Mexico to Bolivia. Molecular phylogenetic studies strongly support the inclusion of Gasteranthus as a member of the New World tribe Beslerieae (Smith, 2000;Roalson & Clark, 2006;Clark et al. 2010). The genus is easily defined by the presence of conspicuous stomatal clusters on the lower leaf surfaces, a feature that is relatively rare in the New World Gesneriaceae. ...
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Two new species from the Cordillera Azul National Park, sector quebrada El Pescadero, Peru, are described and illustrated: Besleria azulensis and B. vanderwerffii. The species were discovered during the botanical expedition of the project “Diversity of flora and its relations with the soil, in the wild zone of Cordillera Azul National Park.”
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Abstract. A new species, Reldia longipedunculata (Gesneriaceae, tribe Beslerieae), is described from the Mache-Chindul Mountains near the border of the Bilsa Biological Research Station in northwestern Ecuador (province of Esmeraldas). The new species differs from all other species of Reldia by the presence of erect peduncles to 10 cm long and narrowly obovate leaves. An updated checklist and key are provided for the seven currently recognized species of Reldia. A previous infraspecific variety is recognized at the species rank as Reldia veraguensis. The presence of pedunculate inflorescences is discussed as a common character in five of the seven species of Reldia.
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A new species of Cremosperma (Gesneriaceae, tribe Beslerieae) is described from the Chocó floristic region of the western Andean slopes of northern Ecuador and southern Colombia. The dorsiventral shoots and strongly anisophyllous leaves differentiate Cremosperma anisophyllum from all other congeners. Se describe una nueva especie de Cremosperma (Gesneriaceae, tribu Beslerieae) de los bosques nublados de la región florística Chocó en las faldas de los Andes en el Norte de Ecuador y el Sur de Colombia. Las ramas dorsiventrales y la hojas anisófilas distinguen a Cremosperma anisophyllum de otras congéneres. Key WordsBeslerieae–Chocó– Cremosperma –Ecuador–Gesneriaceae
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