INVESTIGADORES
GIUSSANI Liliana Monica
artículos
Título:
Breeding System Diversification and Evolution in American Poa supersect. Homalopoa (Poaceae: Poeae: Poinae)
Autor/es:
GIUSSANI L. M., L. GILLESPIE, M.A. SCATAGLINI, M.A. NEGRITTO, A. ANTON & R. SORENG
Revista:
ANNALS OF BOTANY
Editorial:
OXFORD UNIV PRESS
Referencias:
Lugar: Oxford; Año: 2016 vol. 118 p. 281 - 303
ISSN:
0305-7364
Resumen:
?Background and Aims Poa subgenus Poa supersect. Homalopoa has diversified extensively in the Americas. Over half of the species in the supersection are diclinous, most of these are from the New World, while a few are from SE Asia. Diclinism in Homalopoa can be divided into three main types: gynomonoecism, gnodioecism, and dioecism. Here we expand the sampling of species of New World Homalopoa to date its origin and diversification in North and South America and examine the evolution and origin of the breeding system diversity. ?Methods A total of 124 specimens were included in the matrix of which 89 are species of Poa supersect. Homalopoa sections Acutifoliae, Anthochloa, Brizoides, Dasypoa, Dioicopoa, Dissanthelium, Homalopoa s.l., Madropoa and Tovarochloa, and the informal Punapoa group. Bayesian and Parsimony analyses were conducted on the datasets based on for markers: the nuclear ribosomal ITS and ETS, and plastid trnT-L and trnL-F. Dating analyses were performed on a reduced Poa matrix and enlarged Poaceae outgroup to utilize fossils as calibration points. A relaxed Bayesian molecular clock method was used.?Key Results Hermaphroditism appears to be pleisiomorphic in the monophyletic Poa supersect. Homalopoa, which is suggested to have originated in Eurasia 8.4-4.2 Mya. The ancestor of Poa supersect. Homalopoa radiated throughout the New World in the Late Miocene-Early Pliocene with major lineages originating during the Pliocene to Pleistocene (5-2 Mya). We infer at least three major pathways from hermaphroditism to diclinism in New World Homalopoa: two leading to dioecism, one via gynodioecism in South America and another directly from hermaphroditism in North America. A third pathway leads from hermaphroditism to gynomonoecism in Andean species of South America, with strictly pistillate species evolving in the highest altitudes. ?Conclusions Divergence dating provides a temporal context to the evolution of breeding systems in New World Poa supersect. Homalopoa. Our results are consistent with the infrageneric classification in part; we confirm monophyletic sections, propose to reclassify species of sect. Acutifoliae, Dasypoa, and Homalopoa s.l., and suggest that a new sectional treatment is needed for gynomonoecious species.