Phenotypic plasticity of reproductive traits in response to food availability and photoperiod in white-footed mice (Peromyscus leucopus)
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Although most temperate-zone mammals are seasonal breeders, many populations display variation in winter reproductive phenotype. For most mammals, the primary environmental cues regulating reproductive status are food availability and photoperiod, and these two factors can interact in their effect. Low food availability is primarily thought to suppress reproduction by reducing body mass and thereby forcing energy allocations to survival alone. However, because most small mammals rely on an increase in food intake rather than stored nutrients for reproduction, we hypothesized that food availability could act as a signal for low resource availability and affect reproduction even when body condition was not affected. We tested the prediction that restricted food access, without reduced body mass, could alter reproductive responses to short photoperiod. We used genetically distinct lines of white-footed mice (Peromyscus leucopus) derived from a wild population with genetic variation in the neuroendocrine pathway that regulates reproduction in response to environmental cues. The lines were created by artificial selection on gonad size in short photoperiods. Individuals from one line strongly suppress gonadal development in response to short photoperiods, while individuals from the other line suppress gonadal development weakly or not at all. Unresponsive individuals from the selected and an unselected control line were exposed to an intermittent food access protocol that did not affect body mass and only slightly reduced total food intake. We found that restricting food access caused reproductive suppression in short photoperiods but not long photoperiods, with no decrease in body mass. These results provide evidence for an interaction between food and photoperiod that is not dependent upon body condition or energy balance. The results also demonstrate plasticity in the reproductive response to photoperiod of otherwise reproductively nonphotoperiodic white-footed mice.
KeywordsSeasonal breeding Food availability Environmental regulation Energy balance Reproductive strategy
We thank K. King for assistance with mouse care and data collection, and L. L. Moore, A. Pedersen, C. D. Jenkins, and J. R. Reilly for suggestions and comments. Support was provided by the National Science Foundation (IBN-CAREER-9875886), a Batten Scholarship for Pre-Honors Research to S. J. Reilly, and a Cummings summer fellowship to R. Oum.
- Avigdor M, Sullivan SD, Heideman PD (2005) Response to selection for photoperiod responsiveness on the density and location of mature GnRH-releasing neurons. Am J Physiol Regul Integr Comp Physiol 288:1226–1236Google Scholar
- Blank JL, Desjardins C (1985) Differential effects of food restriction on pituitary–testicular function in mice. Am J Physiol 248:R181–R189Google Scholar
- Blank JL, Ruf T (1992) Effects of reproductive function and cold tolerance in deer mice. Am J Physiol Regul Integr Comp Physiol 263:R820–R826Google Scholar
- Bronson FH, Heideman PD (1994) Seasonal regulation of reproduction in mammals. In: Knobil E, Neill JD (eds) The physiology of reproduction, vol 2, 2nd edn. Raven, New York, pp 541–584Google Scholar
- Bronson FH, Heideman PD, Kerbeshian MC (1991) Lability of fat stores in peripubertal wild house mice. J Comp Physiol B 161:15–18Google Scholar
- Carlson LL, Zimmermann A, Lynch GR (1989) Geographic differences for delay of sexual maturation in Peromyscus leucopus: effects of photoperiod, pinealectomy, and melatonin. Biol Reprod 41:1004–1013Google Scholar
- Desjardins C, Lopez MJ (1983) Environmental cues evoke differential responses in pituitary–testicular function in deer mice. Endocrinology 112:1398–1406Google Scholar
- Hansen LP, Batzli GO (1978) The influence of food availability on the white-footed mouse: populations in isolated woodlots. Can J Zool 56:2530–2541Google Scholar
- Prendergast BJ, Nelson RJ, Zucker I (2002) Mammalian seasonal rhythms: behavioral and neuroendocrine substrates. In: Pfaff DW, Arnold A, Etgen A, Fahrbach S, Rubin R (eds) Hormones, brain, and behavior, vol 2. Academic, San Diego, CA, pp 93–156Google Scholar