ENERGY BALANCE BETWEEN GROWTH AND REPRODUCTION IN THE VIVIPAROUS LIZARD Phymaturus punae (LIOLAEMIDAE) FROM THE HIGHLANDS OF THE ANDES? ARGENTINA

BORETTO, JORGELINA; CABEZAS CARTES, FACUNDO; IBARGÜENGOYTÍA, NORA

Cartagena de Indias

Congreso; X Congreso Latinoamericano de Herpetología; 2014

Individuals have a limited amount of energy to be devoted to growth? maintenance and reproduction? so the study of the way in which they use this energy between competing demands is essential to know how they face with their environment. Phymaturus lizards? viviparous and mostly herbivorous? inhabit cold and harsh environments of Andean highlands of Argentina and Chile? and volcanic plateaus of Patagonia. We studied the reproductive effort and its impact on growth in Phymaturus punae? a lizard with a biannual female reproductive cycle and the lowest annual reproductive output of the genus. We estimated age using skeletochronology and found that juveniles ranged from six to nine years? adult females from eight to 18 years? and adult males from nine to 20 years. Juveniles have higher specific growth rates than adults? and adult females have higher specific growth rates than adult males. The adult life span? considering the youngest adult and the maximum age registered? was of 10 years for females and 11 years for males? and the relative reproductive time was 1.25 for females and 1.22 for males. Considering that female reproductive cycle is strictly biannual and the clutch size is one to two offspring? the net reproductive rate resulted in 7.5 offspring along the entire reproductive life of each female. The relative clutch mass was 0.41? the reproductive effort was 0.100? and the lifetime reproductive effort was 1.05. We found a different bone growth pattern in adult males and females. During adulthood a negative correlation was found between the ring number and the ring width in males? while in females the ring width alternate years of higher growth with years of lower growth? and was not correlated with age. Females tend to have wider rings the years that were pregnant and narrower rings the years that performed vitellogenesis. The differential investment in growth between adult males and females of P. punae? is related to differential requirements for reproduction? whereas the trend towards differential investment in growth between vitellogenic and pregnant females suggest differences in the metabolic costs of this reproductive processes? as those recently described in other reptiles. Since P. punae exhibit a high life span? females have a relative low lifetime reproductive effort and net reproductive rate. However? this still represents a high reproductive investment for this species? considering the harsh conditions of the environments where it lives? the viviparous reproductive mode? and the herbivorous diet.