ACCLIMATION, CROSS-GENERATION EFFECTS, AND THE RESPONSE TO SELECTION FOR INCREASED COLD RESISTANCE IN DROSOPHILA

Citation
Mjo. Watson et Aa. Hoffmann, ACCLIMATION, CROSS-GENERATION EFFECTS, AND THE RESPONSE TO SELECTION FOR INCREASED COLD RESISTANCE IN DROSOPHILA, Evolution, 50(3), 1996, pp. 1182-1192
Citations number
23
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Ecology,"Genetics & Heredity
Journal title
ISSN journal
0014-3820
Volume
50
Issue
3
Year of publication
1996
Pages
1182 - 1192
Database
ISI
SICI code
0014-3820(1996)50:3<1182:ACEATR>2.0.ZU;2-Y
Abstract
The way populations respond to selection can be altered when populatio ns are acclimated prior to selection. To examine this possibility, the responses of replicate lines of Drosophila melanogaster and D. simula ns to selection for increased resistance to cold were compared. Flies were selected without hardening or after they had been hardened by hol ding them at 4 degrees C for one hour. The selection response in both species was much greater when Hies were not cold-hardened. Cold resist ance in both sers of selected lines reached a plateau after a few gene rations. Surprisingly, continued selection for increased resistance re sulted in decreasing levels of resistance. This decrease was no longer evident after selection had been relaxed for a generation, suggesting cross-generation effects. The magnitude of the cross-generation effec ts increased with additional generations of selection. Cross-generatio n effects were also detected for fitness components. Relaxing selectio n for a generation increased fecundity, weight, viability, and develop ment time. Comparisons of relaxed lines and control lines indicated th at only fecundity was influenced by selection. Both sets of selected l ines had a lower fecundity than control lines. Crosses between control and selected lines and among replicate selected lines indicated that this decrease in fecundity was not associated with inbreeding. The dir ect and correlated responses to selection for cold resistance can ther efore be influenced by acclimation and cross-generation effects.