Do a male garter snake's energy stores limit his reproductive effort?

Abstract

The storage and utilization of energy plays a critical role in reproductive output for females of many species, including snakes. However, links between energy and reproductive effort in males are less clear. Studies at a communal den of red-sided garter snakes (Thamnophis sirtalis parietalis (Say, 1823)) in Manitoba suggest that energy is critical to reproduction for males as well as females. Males vary substantially in body condition (mass relative to body length) at the time they emerge from winter inactivity. The energy to be expended in courtship is stored in the muscles rather than the "conventional" sites for energy storage in snakes (abdominal fat bodies or liver). A male's reproductive effort (the duration of his residency at courting aggregations near the den) was linked to his energy stores and to the rate of depletion of those stores. Male snakes that emerged from hibernation in better condition, and that lost mass slowly thereafter, remained in courting aggregations near the den for longer periods than did males that emerged in poor condition (i.e., with less energy resources) and (or) lost mass more rapidly. In outdoor arenas, males that engaged in courtship lost mass more rapidly than did males with no courtship opportunities. These data suggest that courtship is energetically expensive for male garter snakes and that the amount of effort that a male invests in reproduction is determined by his energy stores.Résumé : La mise en réserve et l'utilisation de l'énergie jouent un rôle fondamental dans le rendement reproductif des femelles de plusieurs espèces, y compris de couleuvres. Les liens entre l'énergie et l'effort reproductif des mâles sont, cependant, moins évidents. Des études faites à un terrier communautaire de couleuvres rayées (Thamnophis sirtalis parietalis (Say, 1823)) au Manitoba laissent croire que l'énergie est critique pour la reproduction chez les mâles autant que chez les femelles. Les mâles varient considérablement dans leur condition corporelle (masse en fonction de la longueur du corps) au moment où ils sortent de leur inactivité hivernale. L'énergie qui servira à la cour est stockée dans les muscles plutôt que dans les sites plus « réguliers » de mise en réserve de l'énergie chez les couleuvres, comme les corps gras abdominaux ou le foie. L'effort reproductif du mâle (la durée de son séjour près du terrier dans les rassemblements de cour) est en relation avec ses réserves énergétiques et avec le taux d'utilisation de ces réserves. Les couleuvres mâles qui sortent d'hibernation en meilleure condition et qui subissent une diminution subséquente de masse plus lente demeurent au sein des rassemblements de cour près du terrier plus longtemps que les mâles qui émergent en mauvaise condition (c'est-à-dire avec moins de ressources énergétiques) et (ou) qui subissent une perte de masse plus accélérée. Dans les arènes externes, les mâles qui entreprennent des comportements de cour ont des pertes de masse plus rapides que les mâles qui n'ont aucune occasion de faire la cour. Ces données i...

Courtship attention in sagebrush lizards varies with male identity and female reproductive state

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Size dependence in non-sperm ejaculate production is reflected in daily energy expenditure and resting metabolic rate

“…Galimberti et al, 2007;Kotiaho et al, 1998;Lane et al, 2010;Marler et al, 1995;Oberweger and Goller, 2001;Ryan, 1988;Shine and Mason, 2005;Vehrencamp et al, 1989). By experimentally quantifying the energetic costs of nonsperm ejaculate production using robust physiological methods, we show for the first time that non-sperm ejaculate is a large energetic expense, which is comparable with increased metabolic rates of pregnant females.…”

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Phenotypic plasticity of life history traits in relation to reproductive strategies in Boa constrictor occidentalis

“…Considering that the frequency of male and female in mating groups varied between populations and testicular volume is greater in grouped males, we postulate that male reproductive parameters could be related to social mating context. Since the mating system observed in B. c. occidentalis involved extremely costly activities for males (Shine and Mason 2005;Tourmente et al 2009), in poor environments such as Loreto where females are difficult to locate-50% of reproductive females were solitary- (Denardo and Autumn 2001;Kwiatkowski and Sullivan 2002) or male mating competition is less probable-only 39% of reproductive males were in mating groups- (Preston et al 2003;Schulte-Hostedde and Millar 2004) reproductive parameters of males may be expected to be depressed.…”