Great diversity of life forms has favored the colonization and dominance of angiosperms in almost every terrestrial habitat. This is certainly the case in the Orchidaceae, in which the diversity of life forms includes epiphytes, terrestrial geophytes and mycoheterotrophs. In this study
we investigated the evolution of life form in tribe Epidendreae focusing on the clade comprised of Basiphyllaea, Bletia and Hexalectris. We estimated divergence dates, ancestral areas, patterns of niche evolution and divergence/convergence of climate preferences in order
to understand whether shifts in climate preferences can be linked to the evolution of novel life forms, allowing species to extend their distribution ranges into novel habitats. Our analyses corroborated the shift from epiphytism to terrestrial life forms in Epidendreae, which occurred in
a clade with Basiphyllaea-Bletia-Hexalectris that originated in Mexico and Central America from the Mid-Eocene to the Oligocene, coincident with the origin of other aridity-adapted plant groups. Dispersal occurred to North America, South America and the Antilles. Some small aridity-adapted
groups in Hexalectris diverged more recently in the Pliocene and Pleistocene when aridification in North America occurred. Of the climate variables analyzed, annual mean temperature, annual precipitation and precipitation of the wettest month were found to diverge for the terrestrial
clade relative to values associated with the other Epidendreae clades. For niche evolution, Ornstein-Uhlenbeck models indicated that the adaptive optima differed between epiphytes and terrestrial life forms, suggesting a shift of climatic niche between the terrestrial life form clade of Basiphyllaea-Bletia-Hexalectris and the rest of the clades with epiphyte life forms. We suggest that the shift to terrestrial life forms, most noticeable in Hexalectris, favored the colonization of novel habitats with a large range of temperatures, extending the distribution of
this genus northward.
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Article Media
Document Type: Research Article
Biología Evolutiva, Instituto de Ecología AC, Carretera antigua a Coatepec 351, El Haya, 91070 Xalapa, Veracruz, Mexico;, Email: [email protected]
Department of Botany, University of Wisconsin-Madison, Madison, Wisconsin 53706, U.S.A.
Biología Evolutiva, Instituto de Ecología AC, Carretera antigua a Coatepec 351, El Haya, 91070 Xalapa, Veracruz, Mexico
Publication date: 03 May 2016
This article was made available online on 03 April 2016 as a Fast Track article with title: "Life form evolution in epidendroid orchids: Ecological consequences of the shift from epiphytism to terrestrial habit in <i>Hexalectris</i>".
More about this publication?