Regionalization - Evolutionary Biogeography - page 258

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Müller,P.1973. The dispersal centres of terrestrial vertebrates in the Neotropical
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scapes. The Hague: Junk.
Problems
Problem 6.1
Espinosa Pérez and Huidobro Campos (2005) analyzed the distribution of
freshwater fishes in Mexico. Based on a PAE of 450 species distributed in
eight hydrological basins, they found a cladogram ( fig. 6.4 ) that has a basal
dichotomy between a northern and a southern biotic component, with their
separationplacedattheeasternpartoftheTransmexicanVolcanicBelt.The
authors noted that most of the fish species supporting the northern clade
have Nearctic affinities, whereas those from the southern clade had mostly
Neotropical affinities.
The Mexican Gulf biogeographic province, which basically corresponds
with the area analyzed by Espinosa Pérez and Huidobro Campos (2005),
is currently assigned to the Neotropical region, Caribbean subregion, and
Mesoamerican dominion. How would you regionalize this province into dis-
tricts on the basis of the results of their study?