We study here the connections among body temperature variation, flight performance and flight ‘fuel’ metabolism in Colias eurytheme butterflies, to begin re-examining the metabolic reasons for animal thermoregulation. Methods are presented for (a) stable extraction of adenylates (and other metabolites) from the flight muscles of individual Colias eurytheme, (b) automated separation and quantitative analysis of individual adenylate samples by high-pressure liquid chromatography and (c) reliable, low-variance assay of inorganic phosphate levels in the same extracts. Correlations among metabolite concentrations and two indices of muscle cytosol ATP maintenance occur as expected on general metabolic principles. [ATP] and [ATP]/[ADP] decline from resting levels to reach a plateau in the first minute of free, interrupted flight, while [AMP] increases at the same time; these concentrations do not vary further for up to 6 min total flight time. In an initial test of the alternative metabolic bases of the thermoregulation of Colias eurytheme, we find that [ATP]/[ADP] rises between a body temperature, T(b), of 31 and 35 degrees C, at the base of the behavioral thermal optimum for flight, but then decreases again at T(b)=39 degrees C, at the top of the behavioral thermal optimum and well short of damaging temperatures. This is not consistent with the view that metabolic effectiveness increases monotonically up to the lower limits of thermal damage to enzymes, but supports an alternative hypothesis that the narrowness of thermoregulation results from a system-based constraint on the breadth of temperature over which maximal energy processing is possible.

Balaban
R. S.
(
1984
).
The application of nuclear magnetic resonance to the study of cellular physiology
.
Am. J. Physiol
246
,
10
–.
Black
M. J.
,
Jones
M. E.
(
1983
).
Inorganic phosphate determination in the presence of a labile organic phosphate: assayfor carbamyl phosphate phosphatase activity
.
Analyt. Biochem
135
,
233
–.
Carter
P. A.
,
Watt
W. B.
(
1988
).
Adaptation at specific loci. V. Metabolically adjacent enzyme loci may have very distinct experiences of selective pressures
.
Genetics
119
,
913
–.
Ellington
C. P.
,
Machin
K. E.
,
Casey
T. M.
(
1990
).
Oxygen consumption of bumblebees in forward flight
.
Nature
347
,
472
–.
Fiske
C. H.
,
Subbarow
Y.
(
1925
).
The colorimetric determination of phosphorus
.
J. Biol. Chem
66
,
375
–.
Gmeinbauer
R.
,
Crailsheim
K.
(
1993
).
Glucose utilization during flight of honeybee (Apis mellifera) workers, drones and queens
.
J. Insect Physiol
39
,
959
–.
Haldane
J. B. S.
(
1957
).
The cost of natural selection
.
J. Genet
55
,
511
–.
Heinrich
B.
(
1974
).
Thermoregulation in endothermic insects
.
Science
185
,
747
–.
Heinrich
B.
(
1977
).
Why have some animals evolved to regulate a high body temperature?
.
Am. Nat
111
,
623
–.
Kingsolver
J. G.
(
1983
).
Thermoregulation and flight in Colias butterflies: elevational patterns and mechanistic limitations
.
Ecology
64
,
534
–.
Kingsolver
J. G.
(
1983
).
Ecological significance of flight activity in Colias butterflies: implications for reproductive strategy and population structure
.
Ecology
64
,
545
–.
Kingsolver
J. G.
,
Watt
W. B.
(
1983
).
Thermoregulatory strategies in Colias butterflies: thermal stress and the limits to adaptation in thermally varying environments
.
Am. Nat
121
,
32
–.
Krebs
R. A.
,
Feder
M. E.
(
1997
).
Natural variation in the expression of the heat-shock protein hsp70 in a population of Drosophila melanogaster and its correlation with tolerance of ecologically relevant thermal stress
.
Evolution
50
,
173
–.
Mommsen
T. P.
,
Hochachka
P. W.
(
1988
).
The purine nucleotide cycle as two temporally separated metabolic units: a study on trout muscle
.
Metabolism
37
,
552
–.
Sacktor
B.
,
Hurlbut
E. C.
(
1966
).
Regulation of metabolism in working muscle in vivo. II. Concentrations of adenine nucleotides,3154arginine phosphate and inorganic phosphate in insect flight muscle during flight
.
J. Biol. Chem
241
,
632
–.
Sacktor
B.
,
Wormser-Shavit
E.
(
1966
).
Regulation of metabolism in working muscle in vivo. I. Concentrations of some glycolytic, tricarboxylic acid cycle and amino acid intermediates in insect flight muscle during flight
.
J. Biol. Chem
241
,
624
–.
Smith
B. L.
,
Watt
W. B.
(
1995
).
Adenylate levels and environmental stress in the sea anemone Anthopleura elegantissima
.
Mol. Mar. Biol. Biotechnol
3
,
261
–.
Stucki
J. W.
(
1980
).
The thermodynamic buffer enzymes
.
Eur. J. Biochem
109
,
257
–.
Stucki
J. W.
(
1980
).
The optimal efficiency and the economic degrees of coupling of oxidative phosphorylation
.
Eur. J. Biochem
109
,
269
–.
Veech
R. C.
,
Lawson
J. W. R.
,
Cornell
N. W.
,
Krebs
H. A.
(
1979
).
Cytosolic phosphorylation potential
.
J. Biol. Chem
254
,
6538
–.
Watt
W. B.
(
1968
).
Adaptive significance of pigment polymorphisms in Colias butterflies. I. Variation of melanin pigment in relation to thermoregulation
.
Evolution
22
,
437
–.
Watt
W. B.
(
1983
).
Adaptation at specific loci. II. Demographic andbiochemical elements in the maintenance of the Colias PGI polymorphism
.
Genetics
103
,
691
–.
Watt
W. B.
(
1986
).
Power and efficiency as indexes of fitness in metabolic organization
.
Am. Nat
127
,
629
–.
Watt
W. B.
(
1992
).
Eggs, enzymes and evolution: natural genetic variants change insect fecundity
.
Proc. Natl. Acad. Sci. USA
89
,
10608
–.
Watt
W. B.
,
Carter
P. A.
,
Blower
S. M.
(
1985
).
Adaptation at specific loci. IV. Differential mating success among glycolytic allozyme genotypes of Colias butterflies
.
Genetics
109
,
157
–.
Watt
W. B.
,
Carter
P. A.
,
Donohue
K.
(
1986
).
Females' choice of “good types” as mates is promoted by an insect mating system
.
Science
233
,
1187
–.
Watt
W. B.
,
Cassin
R. C.
,
Swan
M. S.
(
1983
).
Adaptation at specific loci. III. Field behavior and survivorship differences among Colias PGI genotypes are predictable from in vitro biochemistry
.
Genetics
103
,
725
–.
This content is only available via PDF.