Chill-coma tolerance, a major climatic adaptation among Drosophila species.
Most drosophilid species can be classified either as temperate or tropical. Adults of species were submitted to a cold treatment (0 degrees C) and then brought back to ambient temperature. They generally exhibited a chill coma and the time needed to recover was measured. We found in a set of 26 temperate species that recovery was rapid (average 1.8 min, range 0.15-4.9). In contrast, a long recovery time (average 56 min, range 24-120) was observed for 48 tropical species. A few species, like Drosophila melanogaster, are cosmopolitan and can proliferate under temperate and tropical climates. In 9 of 10 such species, slight genetic differences were found: a shorter recovery in temperate than in tropical populations. Comparing physiological data to phylogeny suggests that chill-coma tolerance has been a recurrent adaptation that is selected for in cold climates but tends to disappear under a permanently warm environment. This major climatic adaptation, evidenced in drosophilids, seems to occur in other insect groups also.
Gibert
P
P
Laboratoire Populations, Génétique et Evolution, CNRS, Gif sur Yvette, France. gibert@pge.cnrs-gif.fr
Moreteau
B
B
Pétavy
G
G
Karan
D
D
David
J R
JR
D000064:Acclimatization / Q000502:physiology*; D000818:Animals; D005075:Biological Evolution; D003081:Cold Climate; D003128:Coma / Q000503:physiopathology; D004330:Drosophila / Q000502:physiology*; D004331:Drosophila melanogaster / Q000502:physiology; D010802:Phylogeny; D013045:Species Specificity; D013997:Time Factors; D014329:Tropical Climate