Molecular phylogeny of the neotropical genus Christensonella (Orchidaceae, Maxillariinae): Species delimitation and insights into chromosome evolution

Autor(es)

Koehler, Samantha ^[1] ; Cabral, Juliano S. ^[2] ; Whitten, W. Mark ^[3] ; Williams, Norris H. ^[3] ; Singer, Rodrigo B. ^[4] ; Neubig, Kurt M. ^[3] ; Guerra, Marcelo ^[2] ; Souza, Anete P. ^[5] ; Amaral, Maria Do Carmo E. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas, Dept Bot, Inst Biol, BR-13083970 Campinas, SP - Brazil

^[2] Univ Fed Pernambuco, Dept Bot, Ctr Ciencias Biol, BR-50670420 Recife, PE - Brazil

^[3] Univ Florida, Florida Museum Nat Hist, Gainesville, FL 32611 - USA

^[4] Univ Fed Rio Grande do Sul, Dept Bot, IB, BR-91501970 Porto Alegre, RS - Brazil

^[5] Univ Estadual Campinas, Dept Genet & Evolut, Inst Biol, BR-13083970 Campinas, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: ANNALS OF BOTANY; v. 102, n. 4, p. 491-507, OCT 2008.
• Citações Web of Science: 18

Resumo

Background and Aims Species' boundaries applied within Christensonella have varied due to the continuous pattern of variation and mosaic distribution of diagnostic characters. The main goals of this study were to revise the species' delimitation and propose a more stable classification for this genus. In order to achieve these aims phylogenetic relationships were inferred using DNA sequence data and cytological diversity within Christensonella was examined based on chromosome counts and heterochromatin patterns. The results presented describe sets of diagnostic morphological characters that can be used for species' identification. Methods Phylogenetic studies were based on sequence data of nuclear and plastid regions, analysed using maximum parsimony and maximum likelihood criteria. Cytogenetic observations of mitotic cells were conducted using CMA and DAPI fluorochromes. Key Results Six of 21 currently accepted species were recovered. The results also support recognition of the `C. pumila' clade as a single species. Molecular phylogenetic relationships within the `C. acicularis-C. madida' and `C. ferdinandiana-C. neowiedii' species' complexes were not resolved and require further study. Deeper relationships were incongruent between plastid and nuclear trees, but with no strong bootstrap support for either, except for the position of C. vernicosa. Cytogenetic data indicated chromosome numbers of 2n 36, 38 and 76, and with substantial variation in the presence and location of CMA/DAPI heterochromatin bands. Conclusions The recognition of ten species of Christensonella is proposed according to the molecular and cytogenetic patterns observed. In addition, diagnostic morphological characters are presented for each recognized species. Banding patterns and chromosome counts suggest the occurrence of centric fusion/fission events, especially for C. ferdinandiana. The results suggest that 2n 36 karyotypes evolved from 2n 38 through descendent dysploidy. Patterns of heterochromatin distribution and other karyotypic data proved to be a valuable source of information to understand evolutionary patterns within Maxillariinae orchids. (AU)

• Processo FAPESP: 06/58983-6 - Sistema molecular, padrões de diversificação e conservação de orquídeas brasileiras
• Beneficiário: Samantha Koehler
• Modalidade de apoio: Bolsas no Brasil - Jovens Pesquisadores
• Processo FAPESP: 01/08958-1 - Caracteres florais, taxonomia e filogenia de orquídeas Maxillarinae brasileiras
• Beneficiário: Rodrigo Bustos Singer
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 02/02162-3 - Relações filogenéticas e diversificação no complexo Maxillaria madida Hoehne (Maxillariinae, Orchidaceae)
• Beneficiário: Maria do Carmo Estanislau do Amaral
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 02/02161-7 - Relações filogenéticas e diversificação no complexo Maxillaria madida Hoehne (Maxillarinae, Orchidaceae)
• Beneficiário: Samantha Koehler
• Modalidade de apoio: Bolsas no Brasil - Doutorado