Search

The physiology of the long-furred woolly mouse opossum (Micoureus paraguayanus) conformed to that of other marsupials. Body temperature at thermoneutrality (all values reported as mean [+ or -] SE) was 33.3[degrees]C [+ or -] 0.3[degrees]C and basal metabolic rate was 0.760 [+ or -] 0.074 ml [O.sub.2] [g.sup.-1] [h.sup.-1]. Opossums were thermolabile at low ambient temperature ([T.sub.a]) but still maintained a considerable differential between body temperature and [T.sub.a], with an increase in metabolic heat production as [T.sub.a] decreased. This was accommodated by an increase in minute volume, mediated by an increase in both respiratory frequency and tidal volume at low [T.sub.a]. Basal respiratory frequency was 34.2 [+ or -] 3.8 breaths/min and tidal volume was 1.62 [+ or -] 0.28 ml; minute volume was 53 [+ or -] 7 ml/min. Oxygen extraction remained constant at 13.6% [+ or -] 1.1%. Wet thermal conductance was high (0.338 [+ or -] 0.091 ml [O.sub.2] [g.sup.-1] [h.sup.-1] [degrees][C.sup.-1]; 185% of predicted) but conformed statistically to that of other marsupials. A positive relationship existed between ambient temperature and evaporative water loss; standard evaporative water loss was 2.03 [+ or -] 0.21 mg [H.sub.2]O [g.sup.-1] [h.sup.-1]. The point of relative water economy was 11[degrees]C, the lowest yet measured for a marsupial. We found no evidence that this South American marsupial had an elevated metabolic physiology, as might be expected from its neotropical distribution and sympatry with placental mammals. Clearly, marsupials can survive alongside placental mammals without any specific physiological adaptation, although this ability may be restricted to species with generalized low-energy ecological niches. DOI: 10.1644/ 09-MAMM-A-138R.1. Key words: basal metabolic rate, body temperature, evaporative water loss, marsupial, oxygen extraction, relative water economy, ventilation [c] 2010 American Society of Mammalogists

The little red kaluta (Dasykaluta rosamondae) is a small, insectivorous-carnivorous dasyurid marsupial found in arid spinifex grasslands of northwestern Australia. Kalutas resemble other dasyurids in many aspects of their physiology. Body temperature ([T.sub.b]; 33.5[degrees]C; 1.5[degrees]C lower than predicted), wet thermal conductance (1.6 J [g.sup.-1] [h.sup.-1] [degrees][C.sup.-1]; 91% of predicted), and dry thermal conductance (1.22 J [g.sup.-1] [h.sup.-1] [degrees][C.sup.-1]; 55% of predicted) are not significantly different from allometric predictions for marsupials in the thermoneutral zone (26-33[degrees]C). A significantly lower-than-expected basal metabolic rate (0.55 ml [O.sub.2] [g.sup.-1] [h.sup.-1]; 58% of allometric prediction) and evaporative water loss (1.11 mg [g.sup.-1] [h.sup.-1]; 39% of predicted) can be attributed to the combined effect of low [T.sub.b] and phylogeny. Physiological adaptation to aridity is further reflected by a substantially smaller body mass (35 g) than predicted by phylogeny (200 g), a thermolabile [T.sub.b] and use of torpor, which confer significant energy and water savings, and a high point of relative water economy (16.1[degrees]C). Key words: basal metabolic rate, body temperature, evaporative water loss, metabolism, relative water economy, respirometry, torpor

A study was conducted to determine how total phenolic (TP), protein precipitable phenolic (PPP), C, and N concentrations, and amount of protein bound (PB) by PPP in leaves of Desmodium paniculatum (panicled tick-clover; PTC) and Lespedeza cuneata (sericea lespedeza; SL) were affected by simulated herbivory and plant ontogeny. All PTC treatments resulted in a decrease (P ≤ 0.05) in TP, PPP, C, and N concentrations and PB between vegetative and seed set stages. All SL treatments resulted in increased (P ≤ 0.05) or stable TP and PPP concentrations from vegetative stage to seed set. The amount of PB was greatest (P ≤ 0.05) in SL plants submitted to 25% defoliation, and flowering and seed set stages had greater (P ≤ 0.05) PB than the vegetative stage. Ontogenesis and defoliation did not (P > 0.05) affect SL N and C concentrations. The protein binding characteristics of PPP from PTC, but not that of SL, appear to be altered in response to stress. Results might correspond with seed dispersal strategies of the two species, with PTC's epizoochory making increased palatability at seed set beneficial. [ABSTRACT FROM AUTHOR]

Numbats are unusual marsupials in being exclusively diurnal and termitivorous. They have a sparse (1921 hairs cm[sup -2]) and shallow (1.19 mm) pelt compared with other marsupials. Coat reflectivity is low (19%) for numbats compared with nocturnal marsupials, but absorptivity is similar to that of diurnal North American ground squirrels (72%), indicating that the coat of the numbat may be adapted for acquisition of solar heat. Numbat coat thermal resistance decreases significantly with wind speed from 45.9 s m[sup -1] (at 0.5 m s[sup -1]) to 29.8 s m[sup -1] (at 3 m s[sup -1]). Erecting the fur significantly increases pelt depth (6.5 mm) and coat resistance (79.2-64.2 s m[sup -1]) at wind speeds between 0.5 m s[sup -1] and 3 m s[sup -1]. Numbat coat resistance is much lower than that of other marsupials, and wind speed has a greater influence on coat resistance for numbats than for other mammals, reflecting the low pelt density and thickness. Solar heat gain by numbats through the pelt to the level of the skin (60-63%) is similar to the highest value measured for any mammal. However the numbat's high solar heat gain is not associated with the same degree of reduction in coat resistance as seen for other mammals, suggesting that its pelt has structural and spectral characteristics that enhance both solar heat acquisition and endogenous heat conservation. Maximum solar heat gain is estimated to be 0.5-3.6 times resting metabolic heat production for the numbat at ambient temperatures of 15-32.5°C, so radiative heat gain is probably an important aspect of thermoregulation for wild numbats. [ABSTRACT FROM AUTHOR]