Functional and evolutionary correlations of steep leaf angles in the mexical shrubland

Autor: Fernando Valladares, Miguel Verdú, Patricio García-Fayos, Alfonso Valiente-Banuet
Přispěvatelé: Universidad Nacional Autónoma de México, Programa Iberoamericano de Ciencia y Tecnología para el Desarrollo
Rok vydání: 2009
Předmět:
Zdroj: Digital.CSIC. Repositorio Institucional del CSIC
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ISSN: 1432-1939
Popis: 9 páginas, 6 figuras.
In the evergreen shrubland vegetation of Mexico (mexical), most of the species are sclerophyllous woody plants with steep leaf angles. This architectural pattern has been interpreted as a strategy to cope with water shortages and high radiation. However, the current association between evergreenness and steep leaf angles across mexical plant species could be the result of an adaptive association achieved through correlated evolutionary change between both traits or, alternatively, may be the result of common evolutionary ancestry. In this study, we quantiWed leaf angle in 28 dominant species under a phylogenetic framework and evaluated the functional implications of the observed range of leaf angles in terms of leaf temperature, water potentials and transpiration by combining manipulative experiments restraining leaves horizontally with microclimatic and stomatal conductance measurements in selected species and energy balance calculations. Horizontally restrained leaves exhibited reduced water potentials and stomatal conductances, and signiWcantly increased temperatures and transpiration rates. Steeply inclined leaves operated near air temperatures and could sustain relatively high stomatal conductances during the dry season since they were associated with low transpiration rates. Phylogenetic analyses showed that steep leaf angles evolved in a correlated fashion in evergreen species. The functional consequences of leaf angle together with the phylogenetic analysis indicate the adaptive nature of this trait which allows the evergreen species to cope with arid conditions and therefore to persist within the mexical community.
We thank Ing. Rosa M. López, José Antonio Soriano and Lugui Sortibrán for help with the experiments, and Will Cornwell, Steve Kembel, Giles Thelen, and Pedro Villar-Salvador for pertinent criticisms on the manuscript. Campbell Webb and Steve Kembel helped us with the phylocom software. Juan and Carlos Silva Pereyra are thanked for assistance with the preparation of Wgures. Financial support was provided by Dirección General de Asuntos del Personal Académico, UNAM (DGAPA-IN-227605 and IN-224808-3) and CYTED (projects XII-6 and 409AC0369). Experiments comply with the current laws of Mexico.
Databáze: OpenAIRE
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