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Boa constrictor imperator, Belize. JCM |
The Boa constrictor species complex
has the widest distribution of any boid, with a latitudinal range from Mexico
(30° N) to Argentina (35° S), and inhabiting a variety of environments Some
geographically delimited populations have been recognized as subspecies, which exhibit
extensive variation in morphological and ecological traits. Despite their
popularity in the pet trade and relatively high abundance, no comprehensively
detailed phylogeographical studies exist for this species. The only published
work, based mostly on boas from captive breeders, describes two clades (based
upon cytochrome b): one from Mexico and Central America, and the other
encompassing localities from South America. The Central American clade coincides with
the recognized subspecies Boa constrictor
imperator Daudin, 1803.
Suárez‐Atilano and colleagues sampled throughout the range of B. c.
imperator in Neotropical Mexico and continental Central America and used
nuclear and mitochondrial molecular markers to infer the biogeographical
processes that determine population structure in a coalescent framework, an
approach that allows patterns at different spatial and temporal scales to be
examined. The workers characterize the boa’s genetic diversity and
phylogeographical structure to test: (1) whether it demonstrates key spatial
patterns observed in other vertebrates in this region, such as a Pacific–Atlantic
divergence; (2) whether times of divergence of lineages were related to
historical and dispersal events occurring in Mexico and Central America; and (3) whether
biogeographical boundaries in the region, like the Mexican Transition Zone
delimit the current genetic groups.
Cytochrome b results revealed two main reciprocally monophyletic lineages,
one along the Mexican Pacific coast and another along the Gulf of Mexico, Yucatan
Peninsula and Central America, diverging about 5.2 million years ago. Both
lineages are subdivided into haplogroups and show steady historical growth and
a more recent population expansion. High genetic diversity was observed for both
cytochrome b and microsatellites
. The authors demonstrate
a deep phylogeographical structure with two reciprocally monophyletic lineages
and five genetic clusters in Mexico and Central America. And, the results
suggest that several geographical barriers (including the Trans-Mexican
Volcanic Belt and the Motagua–Polochic–Jocoan faults) and ecological features
generated this genetic structure, and suggest that the two lineages may be
considered distinct species.
Citation
Suárez‐Atilano, Marco, Frank Burbrink,
and Ella Vázquez‐Domínguez. "Phylogeographical structure within Boa constrictor imperator across the
lowlands and mountains of Central America and Mexico." Journal of
Biogeography (2014).