The energetics of oviparous reproduction in the African Brown House Snake

Abstract

The energetic cost of reproduction in the oviparous snake, Lamprophis fuliginosus (African Brown House Snake) was compared to other elevated metabolic states, specifically exhaustive activity and digestion. To determine gravidity, female snakes were imaged with a portable ultrasound (CTS‐3300, SIUI America, Inc.). Oxygen consumption was determined using flow through respirometry with carbon dioxide and oxygen sensors (Sable Systems International & AEI Technologies, Inc.). Results indicate that female L. fuliginosus exhibit a significant 29.6% (P=.0310) increase in standard metabolic rate while gravid. An additive effect of gravidity in female snakes during digestion and/or activity could not be measured. Compared to the metabolic cost of exhaustive activity (scope = 4.3; P<.00100) or digestion (scope = 6.70; P=.00100), gravidity (scope = 1.30; P=.0310) is significantly less energetically expensive. Furthermore, our data demonstrate that gravidity does not have a significant influence on time to exhaustion during exhaustive activity (mean = 28.6 minutes P=.400), or the time to peak digestive peak oxygen consumption (mean = 41.7 hours; P=.260). Digestion and activity are inevitable stresses a gravid female must endure. The potentially vulnerable time periods between ingestion and peak oxygen consumption during a meal, and the time it takes for a female to become exhausted during activity are not altered during gravidity. Besides a modest gravid metabolic scope of 1.30, our research has not identified any additional energetic physiological constraints. These results may have significant fitness implications for this species, which we plan to examine further in subsequent studies. Funding for this research was provided by NSF grant IOS 0922756 to JWH.