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Résumé :
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Food supplementation usually advances the timing of laying. Here, we report a meta-analysis of 35 food supplementation studies demonstrating that species at high latitudes are less responsive to food supplementation than those at lower latitudes. Because the length of the breeding season varies with latitude, species at high latitudes may rely mostly upon photic cues and be less responsive to other environmental information. Lower latitude species, where times suitable for breeding vary from year-to-year, are predicted to be more responsive to "supplementary'' information to adjust reproduction to coincide with conditions that favor the successful rearing of young. Studies by Wingfield et al. (Gen Comp Endocrinol 101: 242-255, 1996; Gen Comp Endocrinol 107: 44 62, 1997; Gen Comp Endocrinol 131: 143-158, 2003) suggest a physiological underpinning to this reduced responsiveness to supplementary information in high-latitude species. Given that temperature increases resulting from global climate change are most pronounced at high latitude, reduced plasticity to respond to these changes in individuals of high-latitude species could cause high-latitude breeders to be poorly synchronized with a resource base that emerges earlier than usual. If high-latitude breeders indeed lack sufficient individual-level plasticity to cope effectively with climate fluctuations, effective optimization of reproductive timing in a rapidly changing environment would require similarly rapid evolutionary change. It remains to be seen whether this will be possible.
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