Habitat diversity on the island of Hispaniola. Valle de Bao at the
foothill of Pico Duarte (3098 m) is inhabited by Calisto tasajera;
Arid south eastern coastal habitat in Boca de Yuma provides an
environment for sea oats and associated Calisto lyceius. Credit: A.
Sourakov
In one of the first taxonomic revisions of Neotropical butterflies
that utilizes 'DNA barcoding', Andrei Sourakov (University of
Florida, Florida Museum of Natural History) and Evgeny Zakharov
(University of Guelph, Canadian Centre for DNA Barcoding at the
Biodiversity Institute of Ontario) uncovered a spectacular degree
of evolutionary divergence within the satyrine butterfly
genus Calisto.
The study was published in the open-access journal Comparative
Cytogenetics.
The Caribbean has a remarkable diversity of habitats and wildlife.
More than 200 species of butterflies belonging to some 100 genera
live on the islands, with most genera represented by a single
species. Many species are endemic to the region, that is they do
not occur anywhere else. This distinctive fauna apparently arose as
a result of species immigrating from the mainland at some point
during the islands' history, and later evolving mostly into island
isolates.
The satyrine butterfly genus Calisto is
the most notable of them, because it has the largest number of
extant species compared to other butterfly genera found in the
region. Until the present revision, Calisto had
comprised 54 named taxa, which occupy an extremely diverse array of
habitats, suggestive of adaptive radiation on the scale of other
classic examples, such as the Galápagos or Darwin's finches.
The authors of the study applied a new set of molecular characters
to clarify the classification and evolution of Calisto butterflies.
The 'DNA barcoding' technique is based on the analysis of short,
standardized gene region within mitochondrial DNA, and provides an
efficient method for species identification. As a
result, Calisto now
contains 34 species and 17 subspecies and new data shed light on
the general evolutionary history of the genus.
The discovered spectacular degree of DNA divergence suggests a
diversification period of 4-8 million years. Species
of Calisto that
occur only in Puerto Rico, Cuba, and Jamaica were found likely to
have evolved from various Hispaniolan ancestors. The study found no
support for previously advocated theories of evolution through
geographic separation events due to plate tectonics. The
evolutionary time-frame and the phylogenetic position of
non-Hispaniolan taxa suggest that ancient dispersal events from
Hispaniola to other islands and adaptive radiation within
Hispaniola are likely responsible for the diversification within
the genus Calisto.
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Original source: Sourakov A, Zakharov EV (2011) "Darwin's
butterflies"? DNA barcoding and the radiation of the endemic
Caribbean butterfly genus Calisto (Lepidoptera,
Nymphalidae, Satyrinae). Comparative Cytogenetics 5(3). doi
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