Maternal effects on reproduction in the precocial European hare (Lepus europaeus)

Abstract

In female mammals, reproduction, and in particular lactation, is the energetically most exigent life-history phase. Reproduction is strongly controlled by body reserves and food availability, so females with better body condition or food supply are believed to have higher reproductive output. Additionally, the growth and mortality of young mammals depends on their postnatal development. Therefore, the degree of precociality affects energetic demands for both mothers and young. To study the reproductive performance of the precocial European hare (Lepus europaeus), we analysed relationships between six predictor variables describing maternal and environmental effects and nine response variables relating to reproduction from 217 captive females. We compared the data with those of precocial and altricial mammal species from an extensive literature search. For hares, we found: (1) Heavier females had heavier litters at birth. (2) In summer and spring, total litter mass was larger than in winter. (3) At the end of lactation, the litters of multiparous females were heavier than those of primiparous females. (4) Both older females and females giving birth for the first time had relatively high leveret mortality during lactation. Comparing our results with the literature for other mammals revealed that the body condition (i.e., body mass) of females before birth is predictive of reproductive parameters in both precocial and altricial species. In the precocial hare, female body condition is no longer predictive of reproductive parameters at the end of lactation, whereas in altricial species, female body condition remains predictive of reproduction (litter mass at the end of lactation, offspring mortality) until the end of lactation. We conclude that these effects are caused by precocial offspring feeding on solid food soon after birth and, thus, being less dependent on the mother's body condition during lactation than altricial offspring. In line with this, precociality might have evolved as a way of buffering offspring against maternal effects.

Fig 1

Relationships between a) female body mass at mating and litter mass at birth and b) season of birth and litter mass at birth. Relationships between a) female body mass at mating and litter mass at birth, with the line representing the predicted median values and the grey area displaying the Bayesian credible intervals; and b) season of birth and litter mass at birth, with the points representing the predicted median values and the whiskers displaying the Bayesian credible intervals (n = 52; number of litters = 174). See text for details on statistics.

Fig 2

Relationships between a) female reproductive state and litter mass at the end of lactation and b) female body mass at mating and litter mass at the end of lactation. Relationships between a) female reproductive state and litter mass at the end of lactation, with the points representing the predicted median values and the whiskers displaying the Bayesian credible intervals (n = 40; number of litters = 98); and b) female body mass at mating and litter mass at the end of lactation, with the line representing the predicted median values and the grey area displaying the Bayesian credible intervals. See text for details on statistics.

Fig 3

Relationships between a) female age and leveret mortality and b) female reproductive state and leveret mortality. Relationships between a) female age and leveret mortality, with the line representing the predicted median values and the grey area displaying the Bayesian credible intervals; and b) female reproductive state and leveret mortality, with the points representing the predicted median values and the whiskers displaying the Bayesian credible intervals (n = 54; number of litters = 178). See text for details on statistics.