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Read Ebook: Metabolic Adaptation to Climate and Distribution of the Raccoon Procyon Lotor and Other Procyonidae by Mahlke Johnson Kathleen P Mugaas John N Seidensticker John
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+ <20% by volume when found. | 1%-19% frequency of occurrence. ++ >20% by volume when found. || 20%-50% frequency of occurrence. ||| >50% frequency of occurrence.
For those species for which food habit data are quantified, we used Eisenberg's substrate/feeding matrix method, where "substrate" is analogous to McNab's "behavior," to construct the following feeding categories that are based on the major food groups utilized by each species .
Estimate based on females reproducing in their first or second year.
MINIMUM THERMAL CONDUCTANCE
THERMOREGULATION AND USE OF STORED FAT AT LOW TEMPERATURES
STORED FAT.--Cyclic fattening is an integral and important part of a raccoon's annual cycle ; however, it has not been reported for other procyonids. During winter in parts of the United States and Canada, raccoons are confined to their dens for variable periods of time depending on the severity of the weather . During this confinement, they do not hibernate but rather enter a state of "dormancy" and become inactive. While dormant they remain endothermic and derive most of their energy requirement from fat reserves accumulated during fall. The rate at which fat stores are consumed during winter dormancy depends on the thermoregulatory requirement imposed on them by local weather conditions, the insulative quality of their pelt, and any advantage they may gain by seeking shelter in a den.
THERMOREGULATION AT HIGH TEMPERATURES
TABLE 11.--Distribution by climate of selected procyonid species.
Extends northward from the 10?C isotherm for average annual temperature in the United States.
COMPOSITE SCORES OF ADAPTIVE UNITS AND GEOGRAPHIC DISTRIBUTION
EVOLUTION OF METABOLIC ADAPTATIONS
Several million years exposure to a tropical environment, with its continuous high temperatures and modest range of thermal extremes, would have favored selection of metabolic and thermoregulatory traits that would minimize energy requirements: a lower than predicted basal metabolic rate, a prolonged or continuous molt resulting in very little annual change in minimum thermal conductance, and a modest capacity for evaporative cooling. In addition, we would expect selection to have favored a diverse diet, good reproductive potential, and behavioral flexibility to utilize a variety of habitats within these climates. Our analysis has shown that such characteristics are the norm for extant members of this family living in tropical and subtropical climates, and we speculate that these traits also were common to early procyonids and served to restrict them to these climates. Our speculation is supported by the fact that their known fossil history from the Miocene is confined to geographic areas that had tropical and subtropical climates.
SUMMARY
a potential age of females first producing young
b potential annual birth rate of female young
evaporative water loss
m mass of animal
n potential age of females producing their final young
RQ respiratory quotient
t time
active phase of the daily cycle
heat equivalent of oxygen
heat of vaporization of water
rest phase of the daily cycle
LITERATURE CITED
Aschoff, J?rgen
Aschoff, J., and H. Pohl
Barghoorn, Elso S.
Bartholomew, George A.
Baskin, Jon Alan
Benedict, Francis G.
Berggren, William A.
Bisbal, Francisco J.
Bradley, S. Robert, and Daniel R. Deavers
Brody, Samuel
Calder, William A., and James R. King
Campbell, Gaylon S.
Chevalier, C. D.
Chevillard-Hugot, Marie-Christine, E. F. M?ller, and E. Kulzer
Colbert, Edwin H.
Cole, Lamont C.
Crandall, Lee S.
Crockett, Curtis W.
Darlington, Philip J., Jr.
Davis, D. Dwight
Decker, Denise M.
Decker, Denise M., and W. Chris Wozencraft
Depocas, Florent, and J. Sanford Hart
Dunn, J. P., and J. A. Chapman
Eisenberg, John F.
Ewer, R. F.
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