title: Patterns of oxygen consumption during simultaneously occurring elevated metabolic states in the viviparous snake Thamnophis marcianus.
abstract: Snakes exhibit large factorial increments in oxygen consumption during digestion and physical activity, and long-lasting sub-maximal increments during reproduction. Under natural conditions, all three physiological states may occur simultaneously, but the integrated response is not well understood. Adult male and female checkered gartersnakes (Thamnophis marcianus) were used to examine increments in oxygen consumption (i.e. V̇(O2)) and carbon dioxide production (i.e. V̇(CO2)) associated with activity (Act), digestion (Dig) and post-prandial activity (Act+Dig). For females, we carried out these trials in the non-reproductive state, and also during the vitellogenic (V) and embryogenic (E) phases of a reproductive cycle. Endurance time (i.e. time to exhaustion, TTE) was recorded for all groups during Act and Act+Dig trials. Our results indicate that male and non-reproductive female T. marcianus exhibit significant increments in V̇(O2) during digestion (∼5-fold) and activity (∼9-fold), and that Act+Dig results in a similar increment in V̇(O2) (∼9- to 10-fold). During reproduction, resting V̇(O2) increased by 1.6- to 1.7-fold, and peak increments during digestion were elevated by 30-50% above non-reproductive values, but values associated with Act and Act+Dig were not significantly different from non-reproductive values. During Act+Dig, endurance time remained similar for all of the groups in the present study. Overall, our results indicate that prioritization is the primary pattern of interaction in oxygen delivery exhibited by this species. We propose that the metabolic processes associated with digestion, and perhaps reproduction, are temporarily compromised during activity.
authors.affiliation: Department of Ecology and Evolutionary Biology, School of Biological Sciences, University of California, Irvine, Irvine, CA 92627, USA.
authors.forename: Alexander G S
authors.initials: AG
authors.lastname: Jackson
authors.affiliation: Institute for Clinical and Translational Science, University of California, Irvine, Irvine, CA 92687, USA Department of Pediatrics, University of California, Irvine, School of Medicine, Orange, CA 92868, USA.
authors.forename: Szu-Yun
authors.initials: SY
authors.lastname: Leu
authors.affiliation: Department of Biology, University of Texas at Tyler, Tyler, TX 75799, USA.
authors.forename: Neil B
authors.initials: NB
authors.lastname: Ford
authors.affiliation: Department of Ecology and Evolutionary Biology, School of Biological Sciences, University of California, Irvine, Irvine, CA 92627, USA jhicks@uci.edu.
authors.forename: James W
authors.initials: JW
authors.lastname: Hicks
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D017812:Colubridae / Q000378:metabolism*; D004063:Digestion / Q000502:physiology; D005260:Female; D008297:Male; D010101:Oxygen Consumption; D005082:Physical Exertion; D019518:Postprandial Period; D012098:Reproduction
chemical_list: D002245:Carbon Dioxide
keywords: Activity; Digestion; Oxygen consumption; Prioritization; Reproduction; Thamnophis marcianus