Meeting Abstract

P2.84  Jan. 5  Evidence for arrhythmic activity pattern in a South Florida bufonid MANDICA, Mark L; University of Miami, Coral Gables, Florida mandica@bio.miami.edu

Early natural history notes (Hamilton, 1955; Wright & Wright, 1949; and Duellman & Schwartz, 1958) described the oak toad, Anaxyrus quercicus, as diurnal. These descriptions are postulated upon field observations but have never been confirmed empirically. I collected adults and larvae of both A. quercicus and A. terrestris (the putatively nocturnal Southern toad) near Everglades National Park, Florida. The goals of this study were to: 1) experimentally determine the behavioral rhythm of Anaxyrus quercicus, 2) compare activity patterns between the two bufonids, and 3) determine if an ontogenic shift occurs in activity patterns throughout and after metamorphosis. We used time-lapse videography to sequence toad and larvae movements every 30 seconds for 48 hours (Using a 12:12, 48:0, and 0:48 light cycle). Our preliminary data indicate that A. quercicus is indeed more active during the day than A. terrestris. However, A. quercicus does not entrain to a 12:12 light cycle, suggesting a cathemeral rather than diurnal pattern, as previously suggested. Furthermore, visual and non-visual photoreception information is coordinated in the suprachiasmatic nucleus (SCN) of the mid brain in amphibians. I compared the morphology of the SCN of A. quercicus and A. terrestris using a fluorescent Nissl stain to ascertain any anatomical differences in the mid brain between the two bufonids.