Summary 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.

RESUMENTaxus globosa es una gimnosperma que habita principalmente en los bosques templados de México y el norte de América Central, y que está considerada como amenazada por las agencias de conservación tanto mexicanas como internacionales. En México, una de las mayores amenazas para la mayoría de las especies de los bosques nublados es la pérdida de hábitat, la cual se propicia por la modificación de la cobertura vegetal por factores antropogénicos. Con base en 73 registros de herbario se obtuvo la distribución potencial de la especie mediante el algoritmo Maxent. Asimismo, a partir del modelo obtenido se analizó la modificación de la cobertura vegetal durante tres períodos (1976, 1996 y 2000) y su influencia en la distribución potencial de esta especie. Su distribución potencial fue evaluada en relación con el actual Sistema Nacional de Áreas Naturales Protegidas a nivel federal (ANPs) de México y las Regiones Terrestres Prioritarias para la Conservación (RTPs), con el fin de determinar el papel de estas áreas en su conservación y manejo. Los modelos de distribución potencial muestran que existe una reducción importante del área de distribución (hasta el 84 %) al existir un cambio de uso de suelo. La especie está mal representada en las ANPs, pues menos del 10 % de su área potencial se encuentra dentro de estas áreas de protección federal. Este tipo de análisis representa una herramienta importante en biogeografía y conservación, así como en otras áreas del quehacer biológico, debido a su habilidad predictiva. Nuestros resultados muestran la urgencia que existe de conservar algunos parches de bosques templados mexicanos (principalmente los bosques nublados) para garantizar la existencia de esta especie.Palabras clave: áreas naturales protegidas, distribución potencial, Maxent, romerillo. ABSTRACTTaxus globosa is a gymnosperm inhabiting Mexican and northern Central American temperate forests, and it has been considered as threatened by Mexican and international conservancy agencies. In Mexico, habitat loss is one of the main threats for most of the cloud forest species including this taxon, being human-induced land use change a key issue. We obtained the potential distribution of this species through Maxent algorithm based on 73 herbarium records. Also the modification of vegetation cover for three time periods (1976, 1996 y 2000) was analyzed upon the potential distribution of this species. The known and potential geographical distribution was evaluated in relation to the current Mexican National System of Natural Protected Areas at federal level (ANPs) and Mexican Priority Regions for Conservation (RTPs), in order to determine the role of these areas in its conservation and management. Potential distribution models show an important reduction (until 84 %) of the distribution area related with land use change. This species is scarcely represented in the ANPs, because less than 10 % of its potential distribution occurs within these areas of federal protection. This approach represents an important tool in bio...

Based on known data sets and maximum entropy distribution data of fern and lycopod species registered in the Yucatán Peninsula, track and parsimony analyses were undertaken to evaluate the contribution of these groups to the establishment of biogeographical relationships of the peninsula with other areas. The resulting generalized tracks clearly agree with the geological origin of the peninsula and the previously recognized relationship with the Greater Antilles is not supported for ferns and lycopods. Instead, a Central American generalized track connects the Yucatán Peninsula with south‐eastern México and Central America. Floristically, the peninsula harbours 66 species of ferns and lycopods. Seven are registered for the first time in the Yucatán Peninsula and one is a new species for México. These species do not follow the latitudinal pattern expected if ecological factors, such as humidity and rainfall, were the most important in determining their distributions. Groups of areas recognized with parsimony analysis of endemicity could not be defined as provinces as a result of the lack of endemic species. Nevertheless, a regionalization scheme based on maximum entropy distribution data and supported by track analyses is proposed. Two separate districts are recognized within the Yucatán Peninsula: arid/dry Yucatán in the north and El Petén (humid) in the south. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 775–786.

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