DIFFERENTIAL RESPONSE OF MALE AND FEMALE RING DOVES TO METABOLISM MEASUREMENT AT HIGHER AND LOWER TEMPERATURES

Abstract

From 589 measurements made at 20[degree] and 30[degree] C., on [male][male] and [female][female] of 16 standardized races of ring doves, it is definitely established that the metabolism of the [male] suffers a greater decrease with increase of external temp. than does that of the [female]. Between these limits the decrease in [male][male] is 28.1%, in [female][female] 20.3%. These values are further and fully confirmed by 167 measurements on 10 additional races, and by still other data. Under extreme (and abnormal) depression of the metabolism by a temp. of 30[degree] C. the metabolism of the [female][female] is higher (7.1%) than that of the [male][male]. At 20[degree] C. the measurements of all the 3 large racial groups indicate a higher normal metabolism in the [male] (3 [image]4%). Additional but preliminary measurements made at 15[degree] C. similarly indicate a higher metabolism in [male][male] when measured at this temp. The heat production of certain species and races[long dash]like that of the [male] sex[long dash]is much more depressed by a high external temp. than is that of other species or races. All races of common pigeons studied by the authors are much less affected than are the ring doves. Some races of ring doves[long dash]all of which races have been established on the basis of size of thyroid and pituitary[long dash]are much less depressed than other ring dove races. Measurement at these temp. was preceded during 24 hrs. by maintenance at the same temp., and with all the technique earlier found necessary to the accurate measurement of heat production in these animals. The measurements made at 30[degree] C.[long dash]which is approximately the temp. that yields a minimum metabolism but with this varying somewhat for sex, race and season[long dash]supply evidence that such minimum values are obtained on birds in a non-physiological state. There is already some evidence that this applies to still other animals. This differential response of the normal metabolism of the sexes to temp. is of much consequence not only in metabolism studies, but in growth, vitamin and nutritional research, and in experimental biology generally. In accurate measurements very different results with the 2 sexes may be obtained merely through keeping the animals at, or temporarily subjecting them to, a high or low environmental temp.