Aa. Hoffmann et al., COMPARING DIFFERENT MEASURES OF HEAT-RESISTANCE IN SELECTED LINES OF DROSOPHILA-MELANOGASTER, Journal of insect physiology, 43(4), 1997, pp. 393-405
Lines of the fly Drosophila melanogaster were selected for increased k
nockdown resistance to heat (39 degrees C) in a long tube. One set of
lines was selected following prior heat hardening (1 h at 37 degrees C
) and another without hardening, Each set consisted of three replicate
selection lines and three unselected controls, Lines were tested for
correlated responses to selection, in order to define the nature of kn
ockdown resistance, Selection had a Large effect on knockdown resistan
ce, but selected lines did not differ from controls for knockdown time
in small vials, survival, or recovery time following exposure to heat
, Selection with and without hardening influenced the hardening respon
se in the long tube, but not in small vial assays of resistance, The h
ardened selection lines had decreased resistance to ethanol and a redu
ced dry weight, whereas the non-hardened lines did not show these chan
ges, The same correlated responses were also evident in two generation
experiments on unselected flies, Both sets of lines showed a reductio
n in activity when tested at 37 degrees C, but not at 25 degrees C, Th
ese results indicate that different measures of heat resistance are su
rprisingly unrelated, and suggest that subtle features of the selectiv
e environment influence responses and correlated responses to selectio
n. (C) 1997 Elsevier Science Ltd.