And the frog survived

-- THE outbreak of disease in a population
can cause a large number of deaths, if
unchecked. This decreases the genetic
diversity of the species as a whole. The
species lacking diversity is unable to
adapt to the ever-changing climate and
environmental conditions. This opens
the door for further disease outbreaks.
Gradually the species becomes extinct.

Frog populations are declining
worldwide. But some frogs have found a
way to save themselves from becoming
extinct. A team said outbreak of diseases
in these frog populations is changing the
way they behave.

The team from the UK studied the
common frog species
(Rana temporaria).
Large-scale deaths
caused by the
ranavirus are
common in this
species. Yet the
species has survived
an 83 per
cent decline over
the years. Even its genetic diversity has
been maintained.

The team has a hypothesis to explain
this: the mating behaviour of the frogs
changed or frogs migrated to join
different populations to counter the
virus. The diseased frogs are unable to
mate with healthy frogs; even the
healthy ones prefer to mate with those
that are healthy. Thus mating
amongst individuals from different
populations prevented
important
genes of the
species from getting
lost. The
study was reported
in the August
issue of Molecular
Ecology