Evolutionary determinants of reproductive seasonality: A theoretical approach

Flexible reproductive seasonality in Africa-dwelling papionins is associated with low environmental productivity and high climatic unpredictability

“…Two recent studies found no or little effect of climatic unpredictability on the intensity of reproductive seasonality at the population level, one in chacma baboons (Dezeure et al, 2023) and one on yellow baboons using a modelling approach (Burtschell et al, 2023), questioning the robustness of the effect found in this study. This discrepancy may come from the fact that unpredictable climates select for reproductive flexibility, rather than nonseasonal breeding.…”

“…Flexibility in reproductive phenology may be facilitated by several mechanisms. First, a slower life history may allow papionin species to spread the energetic costs of reproduction over a prolonged period, such that pregnant or lactating females face only a small daily extra energetic expenditure that can be afforded at any time, as suggested by a recent modelling study (Burtschell et al, 2023). In addition, unlike many other mammals, cercopithecids do not use strict photoperiodic cues to trigger their reproduction (Heldstab et al, 2020) but may instead exhibit condition-induced reproduction, whereby conceptions (and/or cycle resumption after lactation) are more likely to occur when females are in better condition (Alberts et al, 2005; Beehner, Onderdonk, Alberts, & Altmann, 2006).…”

“…(2012) found that higher inter-annual variation in food availability decreased the intensity of birth synchrony across 38 ungulate species, two studies of red deer, Cervus elaphus L. (Loe et al ., 2005) and chacma baboons, Papio ursinus (Dezeure et al ., 2023) found no effect of environmental unpredictability on reproductive seasonality. A recent modelling study similarly detected limited effects of environmental unpredictability on evolutionary transitions to nonseasonal breeding (Burtschell et al, 2023).…”

“…The well-known association between latitude and reproductive seasonality fails to explain the diversity of reproductive seasonality patterns observed within restricted latitudinal ranges, such as in the tropics (Heldstab et al, 2020; Janson & Verdolin, 2005). In addition, latitude encapsulates multiple components of climatic variation, which need to be disentangled in order to identify the main climatic factors at play (Burtschell, Dezeure, Huchard, & Godelle, 2023). First, latitude correlates positively with the degree of environmental seasonality, measured as the magnitude of within-year variation (such as the difference between maximal and minimal monthly rainfall in the annual cycle) (Botero, Dor, McCain, & Safran, 2014).…”

“…Further, latitude covaries negatively with environmental productivity, i.e., overall food availability in a given environment. Variation in productivity may alter the benefits of seasonal breeding, as populations living in more productive habitats may face less pressure to breed seasonally (Burtschell et al, 2023).…”