Sex differences in nonshivering thermogenesis in the wild

AbstractSex differences in lifespan and aging are widespread among animals, with males usually the shorter-lived sex. Despite extensive research interest, it is unclear how lifespan differences between the sexes are modulated by genetic, environmental and social factors. We combined comparative data from natural populations of annual killifishes with experimental results on replicated captive populations, showing that females consistently outlived males in the wild. This sex-specific survival difference persisted in social environment only in two most aggressive species, and ceased completely when social and physical contacts were prevented. Demographically, neither an earlier start nor faster rate of aging accounted for shorter male lifespans, but increased baseline mortality and the lack of mortality deceleration in the oldest age shortened male lifespan. The sexes did not differ in any measure of functional aging we recorded. Overall, we demonstrate that sex differences in lifespan and aging may be ameliorated by modulating social and environmental conditions.

Download Full-text

Adaptation to extreme ambient temperatures in cold-acclimated gerbils and mice

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1987.253.1.r39 ◽

1987 ◽

Vol 253 (1) ◽

pp. R39-R45 ◽

Cited By ~ 8

Author(s):

S. Oufara ◽

H. Barre ◽

J. L. Rouanet ◽

J. Chatonnet

Keyword(s):

Evaporative Heat Loss ◽

Electromyographic Activity ◽

Arid Environments ◽

Nonshivering Thermogenesis ◽

Cold Night ◽

Ambient Temperatures ◽

In The Wild ◽

Colonic Temperature ◽

And Control ◽

Thermoregulatory Reactions

To explain tolerance of heat and cold in gerbils (Gerbillus campestris) in their natural environment, a comparative study was made of thermoregulatory reactions in these animals and white mice (Mus musculus) of the same body mass exposed for 2-3 h to ambient temperatures (Ta) ranging from -23 to 40 degrees C. Metabolic rate (MR), evaporative heat loss (EHL), colonic temperature (Tb), and electromyographic activity (EMG) were measured. Nonshivering thermogenesis (NST) was also evaluated from the increase in MR after norepinephrine injection. In gerbils, tolerance of cold was higher than in mice; there was no fall in Tb in cold-acclimated (CA) and control (TN) gerbils after 3 h of exposure at -20 and -10 degrees C Ta, respectively; peak MR (PMR) reached five to six times resting MR (RMR) in gerbils and four to five times in mice. In gerbils, RMR was 35% below that of mice. In TN gerbils, EHL did not increase before 38 degrees C Ta; EHL increased at 26 degrees C in mice. In both animals, cold acclimation increased cold tolerance, PMR, RMR, and NST. Low RMR, high Tb, and mainly burrowing habits preserve gerbils from overheating and save water in hot and arid environments, and a conspicuous tolerance of cold allows them to live and forage in the wild during the cold night.

Download Full-text

Sex differences in the development of termite-fishing skills in the wild chimpanzees, Pan troglodytes schweinfurthii, of Gombe National Park, Tanzania

Animal Behaviour ◽

10.1016/j.anbehav.2004.12.014 ◽

2005 ◽

Vol 70 (3) ◽

pp. 673-683 ◽

Cited By ~ 107

Author(s):

Elizabeth V. Lonsdorf

Keyword(s):

Sex Differences ◽

Pan Troglodytes ◽

National Park ◽

Pan Troglodytes Schweinfurthii ◽

Gombe National Park ◽

In The Wild

Download Full-text

Sex Differences in Head-fixed Running Behavior

10.1101/585000 ◽

2019 ◽

Author(s):

Emily J. Warner ◽

Krishnan Padmanabhan

Keyword(s):

Sex Differences ◽

Male Mice ◽

Specific Difference ◽

Running Wheel ◽

Female Mice ◽

In The Wild ◽

Males And Females ◽

Neural Underpinnings ◽

Divergent Behavior ◽

Almost All

ABSTRACTSex differences in running behaviors between male and female mice occur naturally in the wild. Recent experiments using head restrained mice on a running wheel have exploited locomotion to provide insight in the neural underpinnings of a number of behaviors ranging from spatial navigation to decision making. However, it is largely unknown how males and females behave differently in this experimental paradigm. We found that in head-fixed mice that were initially exposed to a running wheel, all female mice ran forward naturally within the first two days, while almost all male mice scurried backward for up to 4 days. With daily exposure, male mice progressively learned to naturally run forward, with this transition occurring over the course of a 7-day period. Taken together, we have identified a sexually divergent behavior in head-fixed running that should be considered in experiments that use this experimental design. Furthermore, this sex-specific difference could serve as a new way to interrogate the neural underpinnings of a number of behaviors such as anxiety or fear.

Download Full-text

A unified-models analysis of the development of sexual size dimorphism in Damaraland mole-rats, Fukomys damarensis

Journal of Mammalogy ◽

10.1093/jmammal/gyz082 ◽

2019 ◽

Vol 100 (4) ◽

pp. 1374-1386

Author(s):

Jack Thorley ◽

Tim H Clutton-Brock

Keyword(s):

Sex Differences ◽

Sexual Size Dimorphism ◽

Growth Models ◽

Growth Data ◽

Size Dimorphism ◽

Skeletal Size ◽

In The Wild ◽

Parameterized Family ◽

Sigmoid Functions ◽

Reliable Basis

AbstractIndividual variation in growth rates often generates variation in fitness. However, the ability to draw meaningful inferences from growth data depends on the use of growth models that allow for direct comparisons of growth between the sexes, between populations, and between species. Unlike traditional sigmoid functions, a recently parameterized family of unified growth models provides a reliable basis for comparisons since each parameter affects a single curve characteristic and parameters are directly comparable across the unified family. Here, we use the unified-models approach to examine the development of sexual size dimorphism in Damaraland mole-rats (Fukomys damarensis), where breeding males are larger than breeding females. Using skeletal measurements, we show here that the larger size of male Damaraland mole-rats arises from an increased growth rate across the entire period of development, rather than through sex differences in the duration or timing of growth. Male-biased skeletal size dimorphism is not unusual among rodents, and our measures of sex differences in size in captive mole-rats are close to sexual size differences in the wild, where size dimorphism = 1.04 (male:female). We hope our study will encourage the wide use of unified growth models by mammalogists.

Download Full-text