Posted by djo on 13-04-2013 12:50
#2
Hi! There's a big literature on the origin of D. melanogaster.
From memory: Probably a large population-expansion around ~50 thousand years ago, followed by expansion into Europe ~10 thousand years ago (and a small population-bottle-neck at that time). Reached southwestern USA maybe as little as 50-100 years ago.
A good review is set out here: Stephan & Li Heredity (2007) 98, 65–68. doi:10.1038/sj.hdy.6800901;
"The recent demographic and adaptive history of Drosophila melanogaster"
http://www.nature.com/hdy/journal/v98/n2/full/6800901a.html
But I'm afraid it may be behind a pay-wall.