Systematics/Phytogeography / Taxonomie/ Section
Vazquez-Garcia, J. Antonio , Chazaro-Basañez, Miguel de J. , González-Gallegos, Jesús G. .
Floristic and phytogeographical patterns of parasitic species in Mexico.
Trends in species richness, composition and speciation of vascular parasitic communities in Mexico were examined along a latitudinal gradient of over 17 degrees of latitude. Each state in Mexico represented a plant parasitic community. Four matrices with presence/absence data were used. Bray-Curtis technique was used in connection with the Sorensen distance and the sociological favorability index (Beals Smoothing). Direct gradient analysis in connection with regression analyses were also used to determine whether species richness of certain parasitic communities could be explained by latitude or altitude. Throughout a matrix on generic richness among various entities abroad, phytogeographical relationships were examined as well as the influence of Boreal versus Neotropical elements. 1) At the national scale 383 species, three subspecies and 40 genera and 17 families were inventoried for the first time. Mexico showed an extraordinary species richness of vascular parasitic flora from 22 to 40 % greater than expected at the international scale, perhaps due to its unique location in the transition between Holartic and Neotropical realms. Santalales and Scrophulariales, Scrophulariaceae and Viscaceae and the genera Phoradendron, Castilleja and Cuscuta were the most diverse taxa on their category. Aerial (stem) parasites were comparable in richness to that to terrestrial (root) parasites. Over two thirds of the parasitic flora were hemi-parasites and close to one third included holoparasites. 2) Direct (bivariate ordination) showed that latitude explained species richness of Loranthaceae sensu stricto only, while indirect (multivariate) ordination showed that Loranthaceae sensu lato (Loranthaceae and Viscaceae) could also be explained by the latitude. These data suggest the existence of a critical bioclimatic zone between 3000 and 3500 m in elevation where the richness of three of the prominent genera of Viscaceae and Loranthaceae declined drastically.
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1 - Universidad de Guadalajara-CUCBA, Botanica y Zoologia (Instituto de Botanica)., Km. 15.5, Las Agujas, Nextipac., Zapopan, Jalisco, 45110, MEXICO
2 - Universidad de Guadalajara-CUCSH, Geografia y Ordenacion Territorial, Guanajuato 1045, Avenida de los Maestros y Mariano Bárcena, puerta, Guadalajara, Jalisco, 44260, MEXICO
Presentation Type: Poster:Posters for Sections
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM