Meeting Abstract

P1.192  Wednesday, Jan. 4  The benefits and costs of parental care in free-ranging pythons (Liasis fuscus) in tropical Australia STAHLSCHMIDT, Z/R*; SHINE, R; DENARDO, D/F; Arizona State University - Tempe; University of Sydney; Arizona State University - Tempe zrs@dal.ca

Parental care has evolved convergently in many taxa. Life history theory attributes this situation to the benefits of parental care to offspring viability outweighing any costs to parental viability, but such benefits and costs have seldom been measured under field conditions. A population of water pythons (Liasis fuscus) in tropical Australia provides an excellent opportunity to do so because some females brood their eggs only briefly (< 10 days) post-oviposition (“short brooders”), whereas others remain with their eggs throughout the long (> 50-day) incubation period (“long brooders”). We used radiotelemetry, temperature and humidity data loggers, ultrasonography, hematological techniques, and habitat analyses to measure the benefits and costs of maternal nesting decisions (nest-site selection and brooding duration) in 14 free-ranging female pythons over the 4-month reproductive season. Nest-site selection and maternal attendance enhanced thermal and hydric regimes within the nest. While reproducing female pythons experienced high costs (loss of 60% of maternal body mass) due to egg production, additional mass loss due to brooding was low (< 5%) and inversely related to relative fecundity but was surprisingly unrelated to brooding duration. Clutch size was associated with increased parasite load over the course of reproduction. Our results suggest a range of hypotheses for the coexistence of long-brooding and short-brooding tactics within this population, such as a tradeoff between offspring number and quality (long brooders may produce fewer clutches but enhance offspring quality through maternal attendance). Our study provides the first detailed measurements of the costs and benefits of parental care in egg-brooding reptiles, and it provides insight into the tradeoffs mediated by widespread maternal decisions.