caa a22 4500 463175611 CHVBK 20180406164825.0 cr unu---uuuuu 170326e20071201xx s 000 0 eng 10.1007/s10336-007-0172-y doi (NATIONALLICENCE)springer-10.1007/s10336-007-0172-y Adaptation and evolution of photoperiod response systems in birds [Elektronische Daten] [Scott MacDougall-Shackleton, Thomas Hahn] The reproductive cycle of most birds is driven by the annual change in photoperiod, with birds cycling between the physiological states of photosensitivity, photostimulation and photorefractoriness. Comparative studies show that variation in breeding schedules is often correlated with variation in photoperiod response systems. We caution, however, that before adaptive specialization of photoperiod response systems can be concluded, the effects of conditional plasticity and phylogenetic history need to be considered. Conditional plasticity can result in birds with identical response systems displaying different breeding schedules at different latitudes. Consideration of phylogeny can reveal whether parameters of response systems are derived adaptations or ancestral traits. Comparative data on photorefractoriness suggests that one criterion for absolute photorefractoriness—spontaneous regression of the gonads on constant long days—is ancestral in the songbirds. Only four species lack this form of photorefractoriness and all of them are opportunistic breeders. A second criterion for absolute photorefractoriness is insensitivity to even 24h light when birds are refractory. In contrast to spontaneous regression of the gonads, the distribution of this second criterion across species does not support an adaptive hypothesis. In cardueline finches, a lack of photorefractoriness by this second criterion is widespread and is present even among strictly seasonal breeders. Further exploration of the evolution and adaptation of photoperiod responses will require measuring the response of each species to a range of photoperiods and interpreting results within a phylogenetic context. Dt. Ornithologen-Gesellschaft e.V., 2007 Photoperiodism nationallicence Reproduction nationallicence Seasonality nationallicence MacDougall-Shackleton Scott Department of Psychology, University of Western Ontario, N6A 5C2, London, ON, Canada aut Hahn Thomas Section of Neurobiology, Physiology and Behavior, University of California-Davis, Davis, USA aut Journal of Ornithology Springer-Verlag 148(2007-12-01), 219-224 0021-8375 148<219 2007 148 10336 https://doi.org/10.1007/s10336-007-0172-y text/html Onlinezugriff via DOI 1 review-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10336-007-0172-y text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- MacDougall-Shackleton Scott Department of Psychology, University of Western Ontario, N6A 5C2, London, ON, Canada aut NATIONALLICENCE 700 1- Hahn Thomas Section of Neurobiology, Physiology and Behavior, University of California-Davis, Davis, USA aut NATIONALLICENCE 773 0- Journal of Ornithology Springer-Verlag 148(2007-12-01), 219-224 0021-8375 148<219 2007 148 10336 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer