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Climate change imposes an urgent need to recognise and conserve the species likely to be worst affected. However, while ecologists have mostly explored indirect effects of rising ambient temperatures on temperate and polar species, physiologists have predicted direct impacts on tropical species. The African wild dog (Lycaon pictus), a tropical species, exhibits few of the traits typically used to predict climate change vulnerability. Nevertheless, we predicted that wild dog populations might be sensitive to weather conditions, because the species shows strongly seasonal reproduction across most of its geographical range. We explored associations between weather conditions, reproductive costs, and reproductive success, drawing on long-term wild dog monitoring data from sites in Botswana (20°S, 24 years), Kenya (0°N, 12 years), and Zimbabwe (20°S, 6 years). High ambient temperatures were associated with reduced foraging time, especially during the energetically costly pup-rearing period. Across all three sites, packs which reared pups at high ambient temperatures produced fewer recruits than did those rearing pups in cooler weather; at the non-seasonal Kenya site such packs also had longer inter-birth intervals. Over time, rising ambient temperatures at the (longest-monitored) Botswana site coincided with falling wild dog recruitment. Our findings suggest a direct impact of high ambient temperatures on African wild dog demography, indicating that this species, which is already globally endangered, may be highly vulnerable to climate change. This vulnerability would have been missed by simplistic trait-based assessments, highlighting the limitations of such assessments. Seasonal reproduction, which is less common at low latitudes than at higher latitudes, might be a useful indicator of climate change vulnerability among tropical species., (© 2017 The Authors. Journal of Animal Ecology © 2017 British Ecological Society.)

Understanding how reproductive timing has evolved to reflect climatic conditions is increasingly important as the climate changes, influencing species persistence and ecosystem dynamics. Among endotherms, seasonal reproduction is often linked to natural selection for reproducing when biotic conditions (e.g. food availability) are most favourable. In contrast, we present evidence that direct effects of an abiotic factor have selected for seasonal reproduction in a tropical mammal. We have shown previously that the African wild dog (Lycaon pictus), a diurnally active coursing predator, has lower reproductive success at high ambient temperatures, when its hunting activity is constrained. We therefore hypothesized that natural selection would favour reproduction during cool weather conditions, in locations where such conditions occur predictably. We show that, as predicted, wild dogs reproduce seasonally at latitudes from 7 to 25°S, such that their pup‐rearing periods coincide with the coolest (but not the driest) weeks of the year. Wild dog reproduction is aseasonal at latitudes ≤2°. As the climate warms, some temperate‐zone species have tracked optimal conditions through altered phenology. However, in seasonally breeding wild dog populations, any alteration in phenology would require breeding in hotter weather, probably reducing reproductive success. This endangered species may thus have a limited ability to adapt to climate change. Seasonal reproduction might be a trait indicating climate change vulnerability among tropical species. [ABSTRACT FROM AUTHOR]