The energetics of the common mole rat Cryptomy?, a subterranean eusocial rodent from Zambia

Abstract

Body temperature, oxygen consumption, respiratory and cardiac activity and body mass loss were measured in six females and four males of the subterranean Zambian mole rat Cryptomys sp. (karyotype 2 n = 68), at ambient temperatures between 10 and 35 degrees C. Mean body temperature ranged between 36.1 and 33.2 degrees C at ambient temperatures of 32.5-10 degrees C and was lower in females (32.7 degrees C) than in males (33.9 degrees C) at ambient temperatures of 10 degrees C but did not differ at thermoneutrality (32.5 degrees C). Except for body temperature, mean values of all other parameters were lowest at thermoneutrality. Mean basal oxygen consumption of 0.76 ml O2.g-1.h-1 was significantly lower than expected according to allometric equations and was different in the two sexes (females: 0.82 ml O2.g-1.h-1, males: 0.68 ml O2.g1.h-1) but was not correlated with body mass within the sexes. Basal respiratory rate of 74.min-1 (females: 66.min1, males: 87.min-1) and basal heart rate of 200.min-1 (females: 190.min-1, males: 216.min-1) were almost 30% lower than predicted, and the calculated thermal conductance of 0.144 ml O2.g-1.h1.degrees C-1 (females: 0.153 ml O2.g-1.h-1.degrees C-1, males: 0.131 ml O2.g-1.h-1.degrees C-1) was significantly higher than expected. The body mass loss in resting mole rats of 8.6-14.1%.day-1 was high and in percentages higher in females than in males. Oxygen consumption and body mass loss as well as respiratory and cardiac activity increased at higher and lower than thermoneutral temperatures. The regulatory increase in O2 demand below thermoneutrality was mainly saturated by increasing tidal volume but at ambient temperatures < or = 15 degrees C, the additional oxygen consumption was regulated by increasing frequency with slightly decreasing tidal volume. Likewise, the additional blood transport capacity was mainly effected by an increasing stroke volume while there was only a slight increase of heart frequency. In an additional field study, temperatures and humidity in different burrow systems have been determined and compared to environmental conditions above ground. Constant temperatures in the nest area 70 cm below ground between 26 and 28 degrees C facilitate low resting metabolic rates, and high relative humidity minimizes evaporative water loss but both cause thermoregulatory problems such as overheating while digging. In 13-16 cm deep foraging tunnels, temperature fluctuations were higher following the above ground fluctuations with a time lag.(ABSTRACT TRUNCATED AT 400 WORDS)

Life‐history traits, but not season, affect the febrile response to a lipopolysaccharide challenge in highveld mole‐rats

“…obs.) and similar findings have been reported for other mole‐rat species (Marhold & Nagel, 1995). The observed increase of T b from the first to the last baseline measurement suggests that the repetitive handling of the study animals was sufficient to cause significant increases in T b of highveld mole‐rats.…”

Ecophysiological responses to a subterranean habitat; a Bathyergid perspective.

“…These concur with other subterranean mammal studies suggestive of convergent evolution and ecophysiological adaptation (McNab 1966, Withers and Jarvis 1980, Haim and Fairall 1986, Lovegrove 1987, Contreras and McNab 1990, Bennett et al 1992, 1994 Brought to you by | University of California Authenticated Download Date | 6/3/15 4:13 PM Lovegrove andWissel 1988, Marhold andNagel 1995). Resting metabolic rate of subterranean mammals is reduced, regardless of surface climatic conditions.…”

N-dimensional animal energetic niches clarify behavioural options in a variable marine environment

“…Soto et al, 2008), the manoeuvres undertaken during prey pursuit (Weihs, 1981;Hughes and Kelly, 1996), and the accelerations and decelerations involved in catching agile and evasive prey (Soto et al, 2008) and during complex feeding mechanisms (Potvin et al, 2009). Other (also non-diving) animals may have energy expenditure affected by humidity (Marhold and Nagel, 1995), pressure (Lovvorn, 1999), salinity (Pechenik et al, 2000) and light intensity (Boshouwers and Nicaise, 1993), as well as by parameters that animals themselves can change such as speed of movement (Rubenson et al, 2004) and climb angle (Laursen et al, 2000). Our ability to integrate all relevant dimensions enables a better assessment of the consequences of any changes in the environment (both biotic and abiotic) to which organisms are exposed, and determine the extent to which the behavioural repertoire displayed in response to changing conditions may be optimal.…”