A transition zone shows the overlap between two or more regions and represents an event of biotic hybridisation, where different cenocrons assembled as a result of historical and ecological processes. The Mexican transition zone, the area where the Nearctic and Neotropical regions overlap, includes the following five biogeographical provinces: Sierra Madre Occidental, Sierra Madre Oriental, Sierra Madre del Sur, Transmexican Volcanic Belt and Chiapas Highlands. Within this transition zone, the following five cenocrons have already been recognised: Paleoamerican, Mexican Plateau, Mountain Mesoamerican, Nearctic and Typical Neotropical. We undertook three cladistic biogeographic analyses on the basis of 49 cladograms of terrestrial taxa, partitioning them into three time-slices, namely, Miocene (Mountain Mesoamerican cenocron), Pliocene (Mountain Mesoamerican plus Nearctic cenocrons) and Pleistocene (Mountain Mesoamerican, Nearctic and Typical Neotropical cenocrons). For the Miocene time-slice, we observed a close relationship of the Transmexican Volcanic Belt with the Neotropical region, whereas, for the Pliocene and Pleistocene time-slices, the closest relationship of the Transmexican Volcanic Belt was with the Nearctic region. We conclude that the Transmexican Volcanic Belt may have played a different role according to the cenocron analysed, and that the Mexican transition zone differs in its delimitation depending on the taxa analysed, strengthening the idea that it is a complex area.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 29 • No. 6