MEXICAN BIOGEOGRAPHIC PROVINCES: PRELIMINARY SCHEME, GENERAL CHARACTERIZATIONS, AND SYNONYMIES

Although the biogeographic schemes proposed for Mexico are based on different criteria (geographic, paleontological, faunistic or floristic), their authors implicitly acknowledge that the units recognized actually represent historical entities. The development of panbiogeography and cladistic biogeography has challenged traditional classifications, by showing that some of these biogeographic units did not represent natural units. Furthermore, there have been attempts to construct ecogeographic systems, based on the assumption that biotic and abiotic factors constraint species distributions within definite areas. By synthesizing both biogeographic and ecological systems, we propose a new scheme for Mexico, where we recognize the following 14 provinces: California (northern portion of the Baja California peninsula, from Sierras of San Pedro Mártir and Juárez, extending northward along the Sierra Nevada into southwestern USA), Baja California (Baja California peninsula), Sonora (coastal areas in northwestern Mexico, from the northeastern portion of the Baja California peninsula to the Piaxtla river basin in southern Sinaloa), Mexican Plateau (central Mexico, in the states of Zacatecas, San Luis Potosí, Guanajuato, Chihuahua, Coahuila, Durango, and Nuevo Mexico, as well as small parts of Nuevo León, and Sonora, below 4,000 m altitude), Tamaulipas (coastal areas in the northern part of the Mexican Gulf, north of the Pánuco river basin), Sierra Madre Occidental (western Mexico, in the states of Chihuahua, Durango, Zacatecas, Sonora, Sinaloa, Nayarit, and Jalisco, above 1,000 m altitude), Sierra Madre Oriental (eastern Mexico, in the states of San Luis Potosí, Tamaulipas, Coahuila, Hidalgo, Nuevo León, Veracruz, Puebla, and Querétaro, above 1,500 m altitude), Transmexican Volcanic Belt (central Mexico, in the states of Guanajuato, Mexico, Distrito Federal, Jalisco, Michoacán, Puebla, Oaxaca, Tlaxcala, and Veracruz), Balsas Basin (central Mexico, in the states of Guerrero, Mexico, Jalisco, Michoacán, Morelos, Oaxaca, and Puebla, below 2,000 m altitude), Sierra Madre del Sur (south central Mexico, from southern Michoacán to Guerrero and Oaxaca, and part of Puebla, above 1,000 m altitude), Mexican Gulf (coast of the Mexican Gulf, in eastern Mexico, Belize, and northern Guatemala), Mexican Pacific Coast (western Mexico, in the Pacific coast of the states of Sinaloa, Nayarit, Colima, Jalisco, Michoacán, Guerrero, Oaxaca, and Chiapas), Yucatán Peninsula (Yucatán peninsula, in the states of Campeche, Yucatán, and Quintana Roo, below 200 m altitude), and Chiapas (southern Mexico, Guatemala, and Nicaragua, basically corresponding to the Sierra Madre de Chiapas, from 500 to 2,000 m altitude).A pesar de que los esquemas biogeográficos propuestos para México se basan en diferentes criterios (geográficos, paleontológicos, faunísticos o florísticos), sus autores implícitamente asumen que las unidades reconocidas representan entidades históricas. El desarrollo de la panbiogeografía y la biogeografía cladística ha cuestionado estas clasificaciones tradicionales, al mostrar que algunas de estas unidades biogeográficas no representaban unidades naturales. Más aún, ha habido intentos para construir sistemas ecogeográficos, basados en el supuesto que los factores bióticos y abióticos constriñen las distribuciones de las especies dentro de áreas definidas. Aquí proponemos un nuevo esquema para México, al sintetizar ambos sistemas biogeográfico y ecológico, de acuerdo con el cual reconocemos las siguientes 14 provincias: California (porción norte de la península de Baja California, desde las Sierras de San Pedro Mártir y Juárez, extendiéndose hacia el norte a lo largo de la Sierra Nevada en el sudoeste de los Estados Unidos), Baja California (península de Baja California), Sonora(áreas costeras del noroeste de México, desde la porción noreste de la península de Baja California hasta la cuenca del río Piaxtla en el sur de Sinaloa), Altiplano Mexicano (centro de México, en los estados de Zacatecas, San Luis Potosí, Guanajuato, Chihuahua, Coahuila, Durango y Nuevo Mexico, así como pequeñas partes de Nuevo León y Sonora, debajo de los 4,000 m de altitud), Tamaulipas (áreas costeras en la parte norte del Golfo de México, al norte de la cuenca del río Pánuco), Sierra Madre Occidental (oeste de México, en los estados de Chihuahua, Durango, Zacatecas, Sonora, Sinaloa, Nayarit y Jalisco, por encima de los 1,000 m de altitud), Sierra Madre Oriental (este de México, en los estados de San Luis Potosí, Tamaulipas, Coahuila, Hidalgo, Nuevo León, Veracruz, Puebla y Querétaro, por encima de los 1,500 m de altitud), Eje Volcánico Transmexicano (centro de México, en los estados de Guanajuato, México, Distrito Federal, Jalisco, Michoacán, Puebla, Oaxaca, Tlaxcala y Veracruz), Depresión del Balsas (centro de México, en los estados de Guerrero, México, Jalisco, Michoacán, Morelos, Oaxaca y Puebla, por debajo de los 2,000 m de altitud), Sierra Madre del Sur (sur centro de México, desde el sur de Michoacán hasta Guerrero y Oaxaca, y parte de Puebla, por encima de los 1,000 m de altitud), Golfo de México (costa del Golfo de México, en el este de México, Belice y norte de Guatemala), Costa Pacífica Mexicana (oeste de México, en la costa Pacífica de los estados de Sinaloa, Nayarit, Colima, Jalisco, Michoacán, Guerrero, Oaxaca y Chiapas), Península de Yucatán (península de Yucatán, en los estados de Campeche, Yucatán y Quintana Roo, por debajo de los 200 m de altitud) y Chiapas (sur de México, Guatemala y Nicaragua, básicamente corresponde a la Sierra Madre de Chiapas, desde los 500 a los 2,000 m de altitud)

Historical relationships of the Mexican cloud forests: a preliminary vicariance model applying Parsimony Analysis of Endemicity to vascular plant taxa

Abstract Mexican cloud forests, situated between 600 and 3000 m of elevation, exhibit a remarkable high biotic diversity. They follow a fragmented pattern, similar to that of an archipelago, that makes them suitable to vicariance modelling. A Parsimony Analysis of Endemicity (PAE) was applied to the presence/absence of 1267 species of vascular plants (gymnosperms, angiosperms, and pteridophytes) from twenty-four patches of Mexican cloud forests, in order to postulate a preliminary hypothesis of relationships. The single cladogram obtained grouped the twenty-four cloud forests into five clades. These results indicate that the Sierra Madre Oriental, Sierra Madre del Sur, and Serranías Meridionales floristic provinces do not represent natural units. A preliminary vicariance model is presented to explain the sequence of fragmentation of the Mexican cloud forests

Using parsimony analysis of endemicity to analyze the distribution of Mexican land mammals

Patterns of endemism of terrestrial mammals inhabiting Mexico are analyzed by applying Parsimony Analysis of Endemicity (PAE) to 47 ecoregions. The ecoregions were classified in 2 main groups: ecoregions of the Baja California Peninsula and ecoregions of the rest of the country. We found 27 ecoregions with characteristic taxa, and 5 areas of endemism: Northern High Plateau, Baja California, Chiapas, Isthmus, and Yucatan Peninsula. Groups of ecoregions arc basically congruent with other regionalization schemes previously proposed for the country