INVESTIGADORES
BORETTO jorgelina Mariela
congresos y reuniones científicas
Título:
Reproductive patterns in viviparous and oviparous lizards in Patagonia: convergent evolution in the Southern Hemisphere
Autor/es:
N. R. IBARGÜENGOYTÍA, J. M. BORETTO AND M. S. MEDINA
Lugar:
Ciudad de Manaus, Brasil
Reunión:
Congreso; Sexto Congreso Mundial de Herpetología; 2008
Resumen:
Reproduction in temperate climate reptiles is strongly constrained by environmental conditions. Synchronisation of the life cycle with the climatic cycle becomes critical. The timing of the reproductive cycle is an important aspect of the reproductive styles because there is a strong selection to maximize first-year growth in order to minimize winter starvation. Consequently, the reproductive mode, the timing of the reproductive events, and births in favourable climate conditions are of vital importance. In this study, we reviewed the reproductive biology of oviparous and viviparous lizards of the genus Liolaemus, Phymaturus, Homonota and Microlophus from Argentina and Chile and we compare their reproductive traits with lizards from the Southern and Northern Hemispheres. These species show two main female reproductive patterns which are congruent with the biogeographic zones resulting in the observed distributions of insects, fishes, fungi, and plants. Lizards from northern Chile and central Argentina show life history traits that resemble those of lizards from the Neotropical region and Holartic Kingdom, characterized by multiple clutches/litters with short periods of gametogenesis and gestations, early maturity, large clutch size, clutch frequency, and mean annual reproductive output. In contrast, in the highlands of the Andes and the Patagonian steppe of Argentina, life histories traits are more similar to those found in the Austral Kingdom than with close related species at lower latitudes showing the relevance of environmental temperatures on life history traits. At high latitudes, in the Patagonia, a maritime climate provides reptiles with cool environmental temperatures in spring and summer, and long periods of hibernation. These climatic conditions mainly affect the timing of the reproductive events leading to long over-winter vitellogenesis, gestation in spring and summer, small clutch/litter sizes, and late sexual maturity. Viviparous lizards need an entire period of the activity season to perform vitellogenesis and another for pregnancy, whereas in oviparous lizards, vitellogenesis may proceed while development of the eggs continues in the nest, having thus more chances to have annual cycles. Temperate climates of the Southern Hemisphere seem to facilitate the dissociation of prolonged vitellogenesis and pregnancy into separate breeding seasons. Moreover low resources result in skipping of years and multiannual reproduction, especially in viviparous and nocturnal lizards. Males instead do not show a unique reproductive pattern, having high interspecific variation. The present review suggests a causal relationship among environmental factors, conditioned by the access to an appropriate range of temperatures for reproduction resulting in evolutionary convergence among different lineages.