Date: November 6, 2015
Source: Pensoft Publishers
Massive
glaciers once covered an island in one of the Great Lakes, USA, leaving it
largely devoid of life. Its subsequent recolonisation by insects triggered the
curiosity of entomologist R. Edward DeWalt and graduate student Eric J. South
of the Illinois Natural History Survey and Department of Entomology. Not only
did they prove there were significantly fewer species, compared to the
mainland, but also that smaller stonefly species appeared to be more capable of
recolonizing the island. This study was published in the open-access
journal ZooKeys.
Isle
Royale is a large island and national park in the middle of Lake Superior, isolated
from the mainland by 22 -- 70 km distance. As recently as 8,000 -- 10,000 years
ago, glaciers completely covered the island making it almost uninhabitable.
Over
the last 10 millennia mammals as large as moose and wolves, swam, floated,
flew, or walked on ice bridges to the island. Therefore, it seemed logical that
it was the larger size that allowed some species to cross the water. However,
as far as stoneflies are concerned, the results turned out quite different.
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