Ambient temperature effects on photo induced gonadal cycles and hormonal secretion patterns in Great Tits from three different breeding latitudes

• Published in: Hormones and Behavior
• Main Authors: Silverin, Bengt, Wingfield, John, Stokkan, Karl-Arne, Massa, Renato, Järvinen, Antero, Andersson, Nils-Åke, Lambrechts, Marcel M., Sorace, Alberto, Blomqvist, Donald
• Other Authors: Department of Zoology, Göteborgs Universitet = University of Gothenburg (GU), Department of Neurobiology, Physiology, and Behavior, University of California (UC), Kilpisjarvi Biological Station, Centre d’Ecologie Fonctionnelle et Evolutive (CEFE), Université Paul-Valéry - Montpellier 3 (UPVM)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-École Pratique des Hautes Études (EPHE), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD France-Sud )-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), SROPU
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2008
• Subjects: [SDE]Environmental Sciences; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; [SDV]Life Sciences [q-bio]; [SDV.BA]Life Sciences [q-bio]/Animal biology; Northern Finland; Northern Norway
• Online Access: https://hal.science/hal-04261866; https://doi.org/10.1016/j.yhbeh.2008.01.015

International audience The present study determines how populations of Great Tits (Parus major) breeding in southern, mid and northern European latitudes have adjusted their reproductive endocrinology to differences in the ambient temperature during the gonadal cycle. A study based on long-term breeding data, using the Colwell predictability model, showed that the start of the breeding season has a high predictability (≈ 0.8–0.9) at all latitudes, and that the environmental information factor (Ie) progressively decreased from mid Italy (Ie > 4) to northern Finland (Ie < 1). The results indicate that integration of supplementary information, such as ambient temperature, with photoperiodic initial predictive information (day length), becomes progressively more important in maintaining the predictability of the breeding season with decreasing latitude. This hypothesis was verified by exposing photosensitive Great Tits from northern Norway, southern Sweden and northern Italy to sub-maximal photo-stimulatory day lengths (13L:11D) under two different ambient temperature regimes (+ 4 °C and + 20 °C). Changes in testicular size, plasma levels of LH and testosterone were measured. The main results were: (1) Initial testicular growth rate, as well as LH secretion, was affected by temperature in the Italian, but not in birds from the two Scandinavian populations. (2) Maximum testicular size, maximum LH and testosterone levels were maintained for a progressively shorter period of time with increasing latitude, regardless of whether the birds were kept on a low or a high ambient temperature. (3) In birds from all latitudes, the development of photorefractoriness, as indicated by testicular regression and a decrease in plasma levels of LH and testosterone, started much earlier (with the exception for LH Great Tits from northern Scandinavia) when kept on + 20 °C than when kept on + 4 °C. The prolonging effects of a low temperature was more pronounced in Mediterranean birds, than in birds from Scandinavia, and more ...