The Western Ghats of southwestern India and the highlands of
southwestern Sri Lanka, separated by 400 kilometers (km), are
strikingly similar in their geology, climate and evolutionary
history. The Western Ghats, known locally as the Sahyadri Hills,
are formed by the Malabar Plains and the chain of mountains
running parallel to India's western coast, about 30 to 50 km
inland. They cover an area of about 160,000 square kilometeres
(km2) and stretch for 1,600 km from the country's southern tip
to Gujarat in the north, interrupted only by the 30 km Palghat
Gap. Sri Lanka is a continental island separated from southern
India by the 20-meter-deep Palk Strait. The island, some 67,654
km2 in size, has been repeatedly connected with India between
successive interglacials, most recently until about 7,000 years
ago by a land bridge up to about 140 km wide. The Western Ghats
mediates the rainfall regime of peninsular India by intercepting
the southwestern monsoon winds. The western slopes of the
mountains experience hea