GOODWIN, KA; ROSTAL, DC; Georgia Southern University; Georgia Southern University: Maternal Investment in Offspring of Gopherus agassizii: The Consequences of Infection by Mycoplasma agassizii

Upper respiratory tract disease (caused by Mycoplasma agassizii) has been indicated in wide-scale population declines of the Mojave Desert tortoise (Gopherus agassizii). Current USFWS policies advocate the euthanasia or removal of tortoises that test sero-positive for exposure to M. agassizii. However, little is known about how populations respond to this infection. We examined the reproductive output of female sero-positive tortoises compared with those known to be infected and with sero-negative animals. Females were classified into three treatment groups: Negative animals were sero-negative, Positive animals were sero-positive, and Infected animals were sero-negative and subsequently infected with the M. agassizii pathogen by nasal levage. Animals were maintained under natural conditions in outdoor enclosures. Clutch sizes were determined by x-ray. Eggs and hatchlings were weighed and measured. Volume and condition index (CI = mass/volume) were calculated for both eggs and hatchlings. Egg CI and hatchling CI were not different among treatments. Egg volume relative to mother�s volume was significantly different among treatments as was hatchling volume relative to mother�s volume. Positive females had larger eggs relative to female size than Negative females (P<0.0001) and Infected females (P=0.02). Positive females also had larger hatchlings relative to female size than Negative females (P<0.0001) and Infected females (P<0.0001). Negative females had eggs that were larger than those from Infected females (P=0.007) as well as larger hatchlings (P<0.0001). Positive tortoises may be investing more energy into offspring as a response to a chronic deteriorating disease, while infected tortoises are investing more of their energy into fighting a disease that is in its early stage of development.