| Popis: |
High altitude reptiles inhabit adverse environments that condition their reproductive biology. The reproductive and fat body cycles of a high altitude oviparous population of the Common lizard (Zootoca vivipara) in the central Pyrenees were analysed and compared with data on other oviparous and viviparous populations from lower altitudes found in the literature. The studied population shows an extremely short reproductive period. Males show a mixed-type spermatogenesis with very short, vernal spermiogenesis. They emerge from their winter burrows earlier than females and remain unfertile until females start activity and the breeding season begins. Large males release more sperm in copulations than small ones. Females synchronically lay a single clutch per year whereas other oviparous populations living at lower altitudes are iteroparous. Females invest more fat reserves from different compartments (liver, tail) than males, but later in the reproductive season. This major energetic stress seems to be due to the long period of oviductal egg retention. The main effect of altitude on oviparous Zootoca vivipara is the shortening of the reproductive period, which precludes the laying of a second clutch. However, no substantial differences (other than reproductive modality) have been detected between this high mountain oviparous population and viviparous ones. This suggests that not only viviparity but also oviparity is a suitable strategy in such environmental conditions. |
