Table 11.—Distribution by climate of selected procyonid species.
| Species | Tropics | Subtropics | Mild[a] temperate | Cold[] temperate | ||
|---|---|---|---|---|---|---|
| Procyon lotor | + | + | + | + | ||
| Bassariscus astutus | + | + | + | |||
| Nasua nasua | + | + | ||||
| Nasua narica | + | + | ||||
| Procyon cancrivorus | + | + | ||||
| Potos flavus | + | |||||
[a] Extends from the subtropics north to the northern limit of Bassariscus astutus' distribution (Hall and Kelson, 1959:881), which approximates the 10°C isotherm for average annual temperature in the United States (Kincer, 1941).
[] Extends northward from the 10°C isotherm for average annual temperature in the United States.
Composite Scores of Adaptive Units and Geographic Distribution
In [Table 11], procyonid species are arranged in descending order with respect to the number of major climates that are included in their geographic distributions (Hall and Kelson, 1959:878-897; Poglayen-Neuwall, 1975; Kortlucke and Ramirez-Pulido, 1982; Nowak and Paradiso, 1983:977-985). Composite scores ranged from a high of 1.47 for Procyon lotor to a low of 0.39 for Potos flavus, whereas Nasua nasua, Nasua narica, Procyon cancrivorus, and Bassariscus astutus had intermediate values ranging from 0.64 to 0.79 ([Table 12]). [Figure 8] demonstrates that there is a direct relationship between the number of climates these species occupy and their composite scores. Regression analysis (Y = 2.68·X + 0.24; where Y is number of climates, and X is composite score) demonstrates a high degree of correlation between these variables (R = 0.94) and indicates that 89% of the variance in distribution can be explained by composite scores. The various combinations of adaptations expressed by these species do, therefore, play a role in delimiting their climatic (latitudinal) distributions.
Procyon lotor's normalized scores were higher in all categories than those of other procyonids. Procyon lotor, therefore, possesses those traits that have allowed it to become the premier climate generalist of the procyonid family. As an adaptive unit, these traits provide Procyon lotor with the physiological and behavioral flexibility required to take full advantage of a wide range of climates and habitats, and its distribution verifies that it has done so. Even so, it is probably not fair to assume that this species represents a perfect physiological match with climate over its entire distribution. Procyon lotor is, in many respects, still a forest-dwelling species, and its ability to expand its distribution into other habitats such as prairie and desert may well be due, in part, to its use of behavior to take advantage of favorable microclimates in otherwise hostile environments (Bartholomew, 1958, 1987). This feature of Procyon lotor's biology needs to be further examined.
Table 12.—Normalized and composite scores for selected procyonids. (Hbr = ratio of measured to predicted basal metabolism ([Table 7]), Cmwr = ratio of measured to predicted minimum thermal conductance ([Table 7]), Ddr = ratio of food categories actually utilized by each species to total food categories eaten by all six species (calculated from [Table 9]), rmaxr = ratio of calculated to expected rmax ([Table 10]).)