Meeting Abstract

20.10  Jan. 5  Neuroendocrine regulation of breeding in white-crowned sparrows (Zonotrichia leucophrys) O’BRIEN, S.*; BENTLEY, G. E.; TSUTSUI, K.; WINGFIELD, J. C.; Univ. of Washington, Seattle; Univ. of California, Berkeley; Hiroshima Univ., Higashi-Hiroshima; Univ. of Washington, Seattle sobrien@u.washington.edu

Gonadotropin inhibitory hormone (GnIH) & Kisspeptin (KiSS) are two recently discovered hypothalamic neuropeptides found in a variety of vertebrates. In white-crowned sparrows (Zonotrichia leucophrys) (WCSP), GnIH rapidly inhibits plasma LH in castrates, as well as in intact, gonadotropin-releasing hormone-treated birds, and in free-living WCSP with naturally high plasma LH. In contrast, KiSS dose-dependently increases plasma LH in captive, cannulated WCSP. GnIH shows seasonal changes in neuronal attributes implying changes in storage and expression. Thus, we have evidence for potential roles for GnIH & KiSS in the timing of breeding. Subspecies of WCSP exhibit different lengths of breeding seasons. Z. l. gambelii, are arctic breeding birds that must precisely time the onset and cessation of breeding in order to maximize fitness in harsh arctic environments while Z. l. nuttalli are non-migrating sparrows that enjoy a longer breeding season on the coastal chaparral of northern California. Z. l. pugetensis is intermediate in breeding season length, and is expanding its range from coastal to high-altitude mountain sites. GnIH & KiSS peptides may play an important part in the regulation of these variable breeding seasons seen within these subspecies. Furthermore, studying subspecies with different breeding season lengths may illuminate which different ecological factors and reproductive mechanisms influence seasonal breeding.