期刊
HORMONES AND BEHAVIOR
卷 50, 期 3, 页码 347-360出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.yhbeh.2006.03.001
关键词
testosterone; bird; gonadotropin; LH; testes; song control nuclei; season; Parus caeruleus; reproduction; population; adaptation
资金
- NATIONAL INSTITUTE OF NEUROLOGICAL DISORDERS AND STROKE [R01NS035467] Funding Source: NIH RePORTER
- NINDS NIH HHS [NS 35467] Funding Source: Medline
Animal populations living in geographically variable environments respond to different selection pressures. The adaptive character of the responses to environmental information determines the degree of synchrony of the breeding period with local optimal conditions. An example is provided by two populations of Mediterranean blue tits (Parus caeruleus) in Corsica, breeding in different habitats, with a 1-month difference in the onset of egg laying. This difference in the onset of lay is supposed to be adaptive because, although chicks from both populations are raised mostly on caterpillars, the timing of the appearance of caterpillars is earlier for populations of tits associated with deciduous oak trees than those associated with evergreen oak trees. Here, we show that, despite the difference in the timing of egg laying, males from these two populations start seasonal hypothalamo-hypophysial-testicular development at approximately the same time, in late winter. Specifically, the vernal recrudescence of brain GnRH-I perikarya and fibers, testes volume and song activity began around the same dates and proceeded at the same pace in late winter in both populations. Plasma testosterone and LH levels displayed seasonal variations that were shifted by less than 2 weeks compared to the 1-month difference in egg laying periods. We hypothesize that the strong selection pressures on these two populations to adapt the timing of their breeding seasons to their local environment may have acted mostly on the female egg laying dates, and not so much on the initiation and rate of seasonal recrudescence of the hypothalamo-hypophysial-testicular activity in males. (c) 2006 Elsevier Inc. All rights reserved.
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