Physiological Constraints and Latitudinal Breeding Season in the Canidae

Abstract

Physiological strategies that maximize reproductive success may be phylogenetically constrained or might have a plastic response to different environmental conditions. Among mammals, Canidae lend themselves to the study of these two influences on reproductive physiology because all the species studied to date have been characterized as monestrous (i.e., a single ovulatory event per breeding season), suggesting a phylogenetic effect. Greater flexibility could be associated with environments that are less seasonal, such as the tropics; however, little is known for many of the species from this region. To compensate for this lack of data, two regressions were done on the length of the reproductive season relative to the latitudinal distribution of a species: one with raw data and another with phylogenetically independent contrasts. There was a significant negative relationship, independent of phylogeny, with canids that have longer breeding seasons occurring at lower latitudes. In contrast, the pervasiveness of monestrus within Canidae appears to be phylogenetically constrained by their pairing/packing life and is most likely associated with monogamy. The persistence of the monestrous condition is supported by a captive study where a tropical canid, the fennec fox, Vulpes zerda, never exhibited polyestrous cycles despite a constant photoperiod (12L : 12D).

Geographical Origin, Delayed Implantation, and Induced Ovulation Explain Reproductive Seasonality in the Carnivora

“…This exerts a strong selective pressure on short birthing periods at high latitudes. As expected, we found that reproductive periods became shorter with increasing latitude of the natural habitat, confirming previous studies in the Carnivora, which were based on fewer numbers of species (Spady et al, 2007;Valdespino, 2007).…”

“…Our second aim is to explore which physiological, ecological, or social factors are linked to reproductive seasonality in the Carnivora and therefore to our quantitative measure, the birth peak breadth. We assess the influence of 7 factors on reproductive seasonality in the Carnivora that have been suggested previously in the literature to play a role in birth seasonality: namely, day length (photoperiodism) (Bradshaw and Holzapfel, 2007, for a review), latitude of geographical origin (Valdespino, 2007;Zerbe et al, 2012), hibernation (Ferguson et al, 2000;Sandell, 1990), sexual size dimorphism or mating system (Valdespino, 2007;Zerbe et al, 2012), home range size (Spady et al, 2007), and presence or absence of delayed implantation (Bartholomew, 1970;Ferguson et al, 1996;Lindenfors et al, 2003) and induced ovulation (Larivière and Ferguson, 2003;Sanderson and Nalbandov, 1973). For a detailed description of all the predictions for these factors, see the Supplementary material.…”

Reproduction in the endangered African wild dog: Basic physiology, reproductive suppression and possible benefits of artificial insemination

“…The collective evidence suggests that reproduction of the African wild dog is generally seasonal, yet births can occur at every month of the year, supporting the idea that the window of fertility of the African wild dog is broader than described for temperate and arctic zone canids. Valdespino (2007) showed a negative relationship between latitude and the duration of the reproductive season in canid species, with longer reproductive seasons occurring at lower latitudes. Seasonal reproduction is mainly influenced by photoperiod, but also by other factors like temperature, body condition and nutritional intake as described for example in mares (Nagy et al, 2000).…”

Reproductive seasonality in primates: patterns, concepts and unsolved questions

“…We further explore which ecological and biological characteristics are associated with reproductive seasonality in primates. We assess the influence of 11 factors that have been suggested in previous studies to play a role in birth seasonality: latitude and latitude range of the species’ geographical origin (Di Bitetti & Janson, 2000; Zerbe et al ., 2012; Heldstab et al ., 2018 b ), Malagasy origin (Wright, 1999; Janson & Verdolin, 2005), temperature (Zhao & Deng, 1988; Henzi, Byrne, & Whiten, 1992; Fernandez‐Duque, Rotundo, & Ramirez‐Llorens, 2002; Janson & Verdolin, 2005; Tinsley Johnson et al ., 2018), precipitation (such as rain or snow) (Janson & Verdolin, 2005), natural diet (Di Bitetti & Janson, 2000; Janson & Verdolin, 2005), sexual size dimorphism (Valdespino, 2007; Zerbe et al ., 2012), home range size (Spady, Lindburg, & Durrant, 2007), adult female body mass (Di Bitetti & Janson, 2000; Janson & Verdolin, 2005) and life‐history variables correlated with adult body mass such as litter size and gestation length (Bronson, 1989). Furthermore, because primates show a broad variety of substrate use, and substrate may have an impact on how primates change birth season when in zoo conditions compared to the natural habitat, we additionally also include substrate use as a covariate in our analyses.…”