Changes among wild House mice (Mus musculus) bred for ten generations in a cold environment, and their evolutionary implications

Abstract

Wild House mice, Mus musculus, bred at 23°C (controls) changed little in reproductive performance over ten generations. Similar mice bred at 3°C (Eskimo) became more fertile and heavier. Eskimo body fat also rose. Control adrenal weights declined; Eskimo adrenal weights were heavier than those of controls, but only during the first four generations. The Eskimo phenotype after ten generations was a combined result of a direct response to cold, parental effects and genetical changes in the Eskimo population. Maternal effects were probably especially important. In such conditions, the minimum unit of selection that it is useful to consider is the female and her litter.

Morphology, growth and reproduction in the Australian house mouse: differential effects of moderate temperatures

“…No litter losses have previously been reported even at 10 °C (Barnett & Manly, 1959). However, temperatures of 3 °C (Barnett & Dickson, 1984) and −3 °C (Barnett & Manly, 1959) significantly affect numbers of litters weaned, with up to 50% of litters losing some young, even after several generations at cold temperatures (Barnett & Manly, 1959; Barnett & Dickson, 1984). Our results indicate that, for a wild‐derived Australian population, temperatures do not have to be very cold to affect litter outcomes.…”

“…Australian studies have demonstrated that house mouse populations often increase in response to rainfall, although other factors also seem to be important (Singleton & Redhead, 1990; Pech et al ., 1999; Singleton et al ., 2001; Kenney et al ., 2003; Krebs et al ., 2004; Singleton et al ., 2005). One such factor, potentially, is temperature, as cold conditions impact on reproduction in laboratory colonies of wild Australian house mice (Barnett & Dickson, 1984). In regions that suffer particularly heavy outbreaks of mice, such as the semi‐arid wheat‐growing and rangeland areas of eastern and southern Australia (Caughley, Monamy & Heiden, 1994), eruptions of mice often follow mild seasonal conditions when food becomes abundant (Krebs et al ., 2004; Singleton et al ., 2005).…”

Climate warming and Bergmann's rule through time: is there any evidence?

“…After 11 generations, adult males of ‘Eskimo mice’ kept at −3°C were nearly 30% heavier than control mice kept at 21°C. There was no replicate in this experiment, yet the work of Barnett and Dickson () constitutes one of the rare direct tests of Bergmann's rule in a laboratory setting for a mammal.…”

Selection Experiments and Experimental Evolution of Performance and Physiology

“…Although temperature is often the environmental factor of choice in laboratory natural selection studies with Drosophila and microbes (Gibbs and Gefen this volume; Huey and Rosenzweig this volume), we are aware of only one such study with rodents (see also Garland 2003). Barnett and Dickson (1984a, 1984b, and references therein) allowed wild-captured house mice to breed for many generations in either cold (∼3°C) or warm (∼23°C) environments. They chronicled the changes in size, anatomy, life history, and physiology that resulted, and they performed several common-environment experiments to distinguish genetic changes that resulted from the multigenerational exposure to cold and warm environments from the short-term acclimation effects of temperature.…”