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Abstract Detail


Siniscalchi, Carolina Moriani [1], Loeuille, Benoit [2], Pirani, Jose Rubens [3], Mandel, Jennifer R. [4].

Understanding morphological diversity in Chresta (Asteraceae, Vernonieae) and its relationship with other Vernonieae subtribes.

Chresta encompasses 18 species of Compositae, mostly distributed in the Brazilian Cerrado and Caatinga. Plants of this genus present great morphological diversity, despite the relatively small number of species. Species of Chresta are herbs to shrubs, usually with well-developed underground structures, occurring in a number of environments: rock outcrops, savannahs, quartzitic soils, riverbanks, wet soils and areas that suffered anthropic action. The heads are always fused in syncephalia, which can be globular, with strongly fused capitula, or hemispheric, with the heads loosely grouped. In three species the secondary heads present indeterminate growth of their axis, a highly unusual feature within the Vernonieae. Two of the Cerrado species present red flowers and are hummingbird-pollinated, another unusual character in the tribe. The Caatinga species have deeply lobed leaves, silver-green in most of the species. The genus has been either considered part of Eremanthus, due to the secondary heads, or split up into five different genera. Two previous phylogenetic analysis based on molecular markers and morphological data recovered the monophyly of Chresta, but did not present enough support to understand relationships within the genus and with other Vernonieae subtribes, neither brought new insights on how its morphological diversity evolved. In this work we used a previously developed set of 1000 nuclear markers, aiming to achieve a better understanding of its morphological diversity and relations within Vernonieae. Maximum parsimony analysis was ran in TNT, generating one tree, with maximum bootstrap support in 1000 replicates. Maximum likelihood analysis used RAxML, with 1000 bootstrap replicates. Both analysis recovered the same topology for internal relations in Chresta and with other genera in the tribe, with maximum bootstrap support at all nodes, except for one. Chresta martii is sister to all other Chresta species, which are grouped in two clades, representing Caatinga and Cerrado species. The likely ancestral syncephalium type is hemispherical, with loosely joined capitula, with the globose, tightly joined capitula type arising twice, once in each clade. Surprisingly, the two red-flowered species are separated in two different clades, indicating that this character evolved twice in the group history. The clades obtained here loosely follow the generic divisions previously proposed by other authors, but with some of these genera being non-monophyletic. Regarding its relations with other genera, the sister group to Chresta seems to be a clade formed by Vernoniinae and Dypterocypselinae as its sister group, a relationship that had not emerged in previous phylogenetic studies.

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1 - University of Memphis, Department of Biological Sciences, 3700 Walker Ave, Memphis, TN, 38152, USA
2 - Universidade Federal de Pernambuco, Departamento de Botânica, Centro de Ciências Biológicas, Iputinga, Recife, Pernambuco, 50670-901, Brazil
3 - Universidade de So Paulo, Departamento de Botnica, Rua do Mato 277, So Paulo, So Paulo, 05508-090, Brazil
4 - University Of Memphis, 3744 Walker Ave, Memphis, TN, 38152, USA

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Presentation Type: Oral Paper
Session: 29, Phylogenomics I
Location: Fort Worth Ballroom 4/Omni Hotel
Date: Tuesday, June 27th, 2017
Time: 3:45 PM
Number: 29008
Abstract ID:270
Candidate for Awards:None

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