Comparative Study of Growth and Age Two Populations of Homonota darwini (Gekkota: Phyllodactylidae) from Rio Negro and Chubut, Argentina

KUBISCH ERIKA; PIANTONI CARLA; IBARGÜENGOYTÍA NORA

Hotel Panamericano, Ciudad de San Carlos de Bariloche, Argentina

Congreso; VI Southern Connection Congress. Godwana reunited: a southern perspective for a changing world; 2010

In this study, we describe the growth dynamics of two populations of Homonta darwini: from Chubut (CH) and Rio Negro (RN), Argentina. We address two questions: (1) Do populations exhibit different bone growth patterns? (2) Do they vary in body size, age, and growth according to a latitudinal gradient? Skeletochronology was used to obtain estimates of individual age. Both populations present similar bone growth patterns and partial endosteal resorption of the embryonic and first growth-ring. Nevertheless, remodeling did not hinder accurate age determination. In both, growth fits a sigmoidal curve represented by a linear growth in juveniles and asymptotic in adults. Age of juveniles ranges from 1 to 3 years old in CH and from 1 to 4 in RN, and of adults, from 3 to 9 in CH and from 3 to 7 in RN. In sum, RN?s juveniles show lower specific growth rates than CH?s, while RN?s adults present higher growth rates than CH?s (CH: 0.458-0.008 mm/(year*mm) for 20.74 and 48.52 mm SVL geckos, RN: 0.297-0.036 mm/(year*mm) for specimens of 22.80 and 47.00 mm SVL). However, both populations achieve sexual maturity at the same age. A shorter longevity in RN results in a lower maximum fecundity of 5 hatchlings, while in Chubut results in 7. This plasticity agrees with the high versatility of this species to colonize a broad latitudinal range. We stress the need for further investigations, in order to provide further explanation about the main source of variation between these two populations.