August 24, 2016
An international research team
suggests the endangered Cuban solenodon evolved after the extinction of
dinosaurs.
The Caribbean islands form a
natural laboratory for the study of evolution due to their unique biological
and geological features. There has been heated discussion since the early 20th
century on how species appeared on the islands.
The Cuban solenodon is a small,
rare, endangered animal, belonging to the mammalian order Eulipotyphla. It is a
mole-like nocturnal animal with a long snout that feeds on insects and is found
in only a few fragmented locations in Cuba. Its evolutionary origins have been
widely contested and have remained relatively elusive because they have been so
difficult to capture and examine.
In 2012, a team of researchers
successfully captured seven living Cuban solenodons and collected DNA samples
before releasing them. They analysed five specific protein-coding genes and
compared them to the same genes in another 35 species belonging to the same
order.
While another research group had
suggested that solenodons lived with dinosaurs in the Cretaceous period, this
team found that the solenodon family evolved from its ancestor around 59 million
years ago, long after the dinosaur extinction. The team's analysis also
revealed that the Cuban solenodon and the Hispaniolan solenodon (the other
existing solenodon species) diverged from each other in the Early Pliocene
Epoch (3.7 to 4.8 million years ago), while the previous study set the
divergence at 25 million years ago. Hispaniola is the second largest island in
the Caribbean and is currently home to the Dominican Republic and Haiti.
The team now suggests that a
much-later divergence time in addition to information on ocean-current patterns
in the area indicate that the Cuban solenodon travelled over water (on floating
plants or rafts, for example) to Cuba from Hispaniola, rather than
evolutionarily diverging from them due to the much-earlier geological
separation of the islands.
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