Meeting Abstract
44.5 Saturday, Jan. 5 Living Life Like There Is No Tomorrow: Growth, Sex, And Death In A Remarkable Chameleon In Madagascar KARSTEN, K.B.*; ANDRIAMANDIMBIARISOA, L.N.; FOX, S.F.; RAXWORTHY, C.J.; Oklahoma State Univ.; Univ. of Antananarivo; Oklahoma State Univ.; American Museum of Natural History kris.karsten@okstate.edu
For unknown reasons, the approximately 28,300 species of tetrapods almost exclusively have perennial life spans. However, organisms experiencing increased mortality rates may evolve shorter life spans, possibly as a result of the cost associated with rapid growth or early reproductive effort, both of which decrease longevity. Tetrapods susceptible to extreme heat and desiccation also may evolve rapid development and therefore be likely to exhibit brief life spans. Here, we report the discovery of an annual tetrapod from the arid southwest of Madagascar, the chameleon Furcifer labordi, with a post-hatching life span of a mere 4-5 months. At the start of the active season (November), an age-cohort of hatchlings emerges, but no juveniles or adults appear. These hatchlings grow rapidly and reach sexual maturity in less than two months, reproduce in January-February, with senescence soon becoming apparent and subsequent population-wide death occurring. Consequently, during the dry season, the entire population is represented by a single age-cohort of developing eggs that incubate for 8-9 months (with a developmental diapause) and then synchronously emerges at the onset of the following rainy season. Our review of tetrapod longevity (>1,700 species) finds no others with such a short life span for both sexes. The evolution of this life history strategy may be associated with the small adult body size of this chameleon, which we suspect may result in reduced survivorship for adults compared to eggs during the prolonged dry season. These results provide new insights into the plasticity of tetrapod life-history evolution and potentially explain the notorious rapid death of chameleons in captivity; something of special significance for species of conservation concern.
