| Species | Body mass (g) | a | b | n | rmax | rmaxe[a] | rmaxr[] | References |
|---|---|---|---|---|---|---|---|---|
| Procyon lotor | 4940 | 0.83 | 2.25 | 16 | 1.34 | 0.53 | 2.52 | Dunn and Chapman (1983); Eisenberg (1981:489); Kaufmann (1987); Lotze and Anderson (1979); Nowak and Paradiso (1983:981); Sanderson(1987); Stains (1956:28-31); This study |
| Bassariscus astutus | 900 | 0.83 | 1.50 | 14 | 1.02 | 0.82 | 1.24 | Kaufmann (1982, 1987); Nowak and Paradiso(1983:979, 980); Poglayen-Neuwall and Poglayen-Neuwall (1980); Poglayen-Neuwall and Toweill (1988); Russell (1983) |
| Nasua narica | 3900 | 2.50 | 2.25 | 14 | 0.62 | 0.56 | 1.11 | Kaufmann (1982, 1987); Nowak and Paradiso (1983:983); Sanderson (1983) |
| Nasua nasua | 3850 | Chevillard-Hugot et al. (1980) | ||||||
| Procyon cancrivorus | 1160 | 0.83 | 1.50 | 15 | 1.02[c] | 0.77 | 1.32 | Crandall (1964:312); Poglayen-Neuwall (1987) |
| 1.75 | 0.65[c] | 0.84 | ||||||
| Potos flavus | 2490 | 1.75 | 0.50 | 12 | 0.30 | 0.63 | 0.48 | Ford and Hoffmann (1988); Nowak and Paradiso (1983:984) |
| Bassaricyon gabbii | 1600 | 1.75 | 0.50 | 15 | 0.32 | 0.71 | 0.45 | Eisenberg (1981:489); Nowak and Paradiso (1983:985) |
[a] rmaxe = 4.9·m0.2622, where m is body mass in grams.
[] Regression of rmax on body mass (m). Assume rmax = 1.02 for Procyon cancrivorus: rmax = 0.00005·m + 0.623; R = 0.19; R2 = 0.03; Regression of rmaxr ([Table 10]) on Hbr ([Table 7]); assume Nasua nasua has the same rmaxr as Nasua narica: rmaxr = 3.35·Hbr - 1.11; R = 0.93; R2 = 0.86.
[c] Estimate based on females reproducing in their first (a = 0.83) or second (a = 1.75) year.
Nasua nasua.—Unfortunately, there is not enough reproductive data to allow calculation of rmax for Nasua nasua ([Table 10]), therefore, it is not possible to compare the reproductive potential of this South American coati with its North American relative, Nasua narica. Given its low Ḣb and relatively low-quality diet of fruit and terrestrial invertebrates ([Table 9]), however, rmax of Nasua nasua may be very similar to that of Nasua narica.
Procyon cancrivorus.—The age of first female reproduction for Procyon cancrivorus has not been reported. However, if one assumes females can reproduce in their first year, rmax for Procyon cancrivorus would be 1.02 (132% of expected; [Table 10]). If, on the other hand, first female reproduction is delayed until the second year, rmax would be 0.65 (84% of predicted; [Table 10]). Procyon cancrivorus has a low Ḣb, reduced litter size, and small body mass. Its low Ḣb may limit litter size, but as with Bassariscus astutus, the quality of its diet (a high percentage of small vertebrates; [Table 9]) and its small body size may make it possible for females to reproduce in their first year and thus increase the species' reproductive potential. This reasoning would argue that Procyon cancrivorus probably enjoys higher, rather than lower, than expected rmax.
Potos flavus.—In addition to a low Ḣb, this species possesses other characteristics that limit its reproductive potential: low-quality diet, delayed reproduction, and birth of a single young each year. Because there does not appear to be any other feature of its life history that can counteract the influence of these factors, rmax in Potos flavus has evolved to be only 48% of expected (0.30; [Table 10]). Its close relative, the olingo, Bassaricyon gabbii, appears to share the same condition ([Table 10]).
Summary.—This brief survey illustrates that, with the exception of Potos flavus, procyonids tend to have values of rmax that are higher than those predicted for them on the basis of mass ([Table 10]). Regression analysis indicates that, within the family, body mass accounts for only a small amount (3%) of the variation in rmax, whereas the positive slope of the correlation between rmaxr and Hbr (R = 0.93) suggests that low metabolism has a limiting effect on rmax (see [Table 10, footnote b]). The implication here is that low Ḣb would be associated with a lower rate of biosynthesis, a slower growth rate, and a longer generation time. Procyonids with low Ḣb but higher than expected rmax must possess other traits that serve to offset the effects of low metabolism. Our survey indicates that the following features compensate for low Ḣb and help increase rmax: (1) a high-quality diet may make biosynthesis and growth more efficient, thus optimizing the time element associated with each of these processes; (2) larger litter sizes and cooperation in care of the young may increase survivorship in spite of a slower growth rate; and (3) an early age of first reproduction, a long reproductive life span, and moderate-size litters (two to four young) may in the long run add as many individuals to the population as a shortened generation time. Our survey also suggests that, at the other extreme, factors such as a low-quality diet, reduced litter size, absence of cooperative care of the young, delayed age of first reproduction, and shortened reproductive life span all serve to decrease rmax. Thus, it is obvious that diet, litter size, social structure, reproductive strategy, and reproductive life span can operate synergistically with Ḣb to magnify its influence on rmax (as with Procyon lotor and Potos flavus), or they can function in opposition to Ḣb to change the direction of its influence on rmax (as with Bassariscus astutus, Procyon cancrivorus, Nasua narica, and perhaps Nasua nasua).