Basic considerations on seasonal breeding in mammals including their testing by comparing natural habitats and zoos
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Basic considerations on seasonal breeding in mammals including their testing by comparing natural habitats and zoos Marcus Clauss1 · Philipp Zerbe1 · Laurie Bingaman Lackey2 · Daryl Codron3 · Dennis W. H. Müller4 Received: 24 August 2020 / Accepted: 7 October 2020 © The Author(s) 2020
Abstract Seasonal reproduction is common in mammals. Whereas specific conditions triggering a seasonal response can only be identified in controlled experiments, large-scale comparisons of reproduction in natural habitats and zoos can advance knowledge for taxa unavailable for experimentation. We outline how such a comparison can identify species whose seasonal physiology is linked to photoperiodic triggers, and those whose perceived seasonality in the wild is the consequence of fluctuating resources without a photoperiodic trigger. This concept groups species into those that do not change their aseasonal pattern between natural habitats and zoos because they are not constrained by resources in the wild, those that do not change a seasonal pattern between natural habitats and zoos because they are triggered by photoperiod irrespective of resources, and those that change from a more seasonal pattern in the natural habitat to an aseasonal pattern in zoos because the zoo environment alleviates resource limitations experienced in the wild. We explain how detailed comparisons of mating season timing in both environments can provide clues whether a specific daylength or a specific number of days after an equinox or solstice is the likely phototrigger for a taxon. We outline relationships between life history strategies and seasonality, with special focus on relative shortening of gestation periods in more seasonal mammals. Irrespective of whether such shortening results from the adaptive value of fitting a reproductive cycle within one seasonal cycle (minimizing ‘lost opportunity’), or from benefits deriving from separating birth and mating (to optimize resource use, or to reduce infanticide), reproductive seasonality may emerge as a relevant driver of life history acceleration. Comparisons of data from natural habitats and zoos will facilitate testing some of the resulting hypotheses. Keywords Reproduction · Breeding · Seasonality · Body condition · Life history · Zoo
Introduction Many mammals are subject to seasonal fluctuations in their environment. Seasonal changes affecting food availability and convective temperature loss determine the animal’s Handling editor: Yoshiyuki Henning.
energy budget (Bronson 2009). Among the various adaptations to these fluctuations, seasonal reproduction plays a central role (Bronson 1989; Bronson and Heideman 1994) to ensure the survival of the offspring and (lactating) mothers. Many crucial hormonal and genetic mechanisms linked to seasonal reproduction have been elucidated in selected species by detailed experimental investigations
* Marcus Clauss [email protected]
1
Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
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