Meeting Abstract

P3.105  Tuesday, Jan. 6  Effects of habitat quality on maternal investment in two Georgia populations of Gopherus polyphemus. ENTZ, J. E.*; ROSTAL, D.C.; Georgia Southern University jentz1211@yahoo.com

Food for Gopherus polyphemus hinges on diversity of burn influenced herbaceous ground cover. 2 populations with different burn regimes were studied. Fort Stewart Army Reservation (FSAR) is frequently burned; George L. Smith State Park (GLS) is infrequently burned. FSAR females are significantly larger & produce significantly larger eggs & hatchling masses. Females at GLS might be sacrificing size & the potential of larger clutches to start reproduction earlier. Our objective was to examine the change in maternal investment between sites & its affects on the hatchling growth & survivorship. Female tortoises were collected from May-July (2007, 2008), measured, X-rayed, & examined to determine clutch size. X-rays from 07-08 were measured to obtain egg size, female size, & pelvic opening. 8 nests in 07 were located at each site & temperature dataloggers were set to measure incubation conditions. Eggs were allowed to incubate in the field for the majority of development. During 08, 2 nests from GLS and 6 nests from FSAR were monitored in the same manner as 07. During 08, 1 egg from each nest was removed for component analysis. Hatchlings from 07 were given equivalent resources & measured bi-weekly for 1 yr to obtain growth rates. Females from both locations appear to be investing equivalent amounts of energy into reproduction in proportion to body size. Measurements from X-rays demonstrate females from both locations are constrained by pelvic size & are produce eggs as large as possible for body size. Hatchlings from both locations had similar growth rates, indicating that observed phenotypic plasticity is due to habitat quality. So far, variables measured indicate that habitat quality is leading to different reproductive patterns in the 2 populations of G. polyphemus.