Phenotypic plasticity of reproductive traits in response to food availability and photoperiod in white-footed mice (Peromyscus leucopus)

Abstract

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.

Effects of photoperiod and food restriction on the reproductive physiology of female California mice

“…However, our results demonstrate that short days sensitize the female reproductive tract to energy limitations. While this finding contradicts our original hypothesis, it is consistent with work done in other rodents that are non-obligate photoperiodic breeders including male rats [5] and white-footed mice selected against a photoperiodic response [34], where food restriction reduced gonadal size under short days or in the presence of exogenous melatonin, but not long days alone. Food restriction has been suggested to increase the inhibitory effects of melatonin on reproduction [5].…”

Plasticity in gastrointestinal morphology and enzyme activity in lactating striped hamsters (Cricetulus barabensis)

“…The stomach, small and large intestine and cecum in lactating hamsters were larger in size than in the non-reproductive and post-lactating animals. Such marked plasticity has also been observed in many other animals (Campbell and Fell, 1964;Derting and Austin, 1998;Hammond et al, 1996;Koteja, 1996a;Reilly et al, 2006;Simons et al, 2011;Speakman and McQueenie, 1996). Moreover, significant plasticity was observed in the digestive enzymes among the non-reproductive, lactating and post-lactating hamsters.…”

“…Moreover, these changes in organism traits due to changes in internal or external environmental conditions can occur over a short time scale and are reversible (Hammond et al, 1999(Hammond et al, , 2001Karasov and Diamond, 1983;Karasov and Hume, 1997;Nagy and Negus, 1993;Piersma and Drent, 2003;Piersma and Lindström, 1997). For example, notable plasticity in digestive physiology has been shown in rodents in energetically stressful periods such as lactation, which is generally believed to determine an individual's reproductive strategy and thus influence the probability of reproductive success (del Valle et al, 2004;Hammond and Kristan, 2000;Koteja, 1996a;Naya et al, 2008a;Reilly et al, 2006).…”

Reproductive plasticity and local adaptation in the host–parasite system formed by the toxic Alexandrium minutum and the dinoflagellate parasite Parvilucifera sinerae

“…This kind of plasticity has been described in mammals (e.g., Reilly et al, 2006), invertebrates (e.g., McGovern, 2003), fish (e.g., Aubin-Horth and Dondson, 2004), and plants ( Barot et al, 2005) but, to our knowledge, never in organisms capable of both sexual and asexual reproduction. This dual life-cycle pattern makes these organisms very interesting from an evolutionary point of view as during parasite attack it necessitates a choice between faster reproduction and the emergence of genetically different offspring.…”