Synchronized versus asynchronized breeding in cordylid lizards: an evolutionary perspective

The relationship between generation gland morphology and armour in Dragon Lizards (Smaug): a reassessment of ancestral states for the Cordylidae

To substantiate the claim of a relationship between generation gland morphology and degree of body armour in cordylid lizards, we studied the nine species in the genus Smaug. We predicted that well armoured species in this clade will have multi-layer generation glands, and lightly armoured species two-layer glands. Gland type was determined using standard histological techniques after sectioning a glandular patch of one adult male per species. A total of 133 specimens were examined for data on tail and occipital spine lengths (which were used as indicators of armour). We found that species with multi-layer generation glands (S. giganteus, S. breyeri, and S. vandami) have relatively long tail and occipital spines, while species with two-layer glands (S. mossambicus, S. regius, S. barbertonensis, S. warreni, and an undescribed species) have relatively short spines. Smaug depressus possesses both multi-layer and two-layer glands, and this variation was linked to regional variation in spine length. An ancestral state reconstruction for the Cordylidae showed that the two-layer state always results from the reduction of layers from a multi-layer precursor, and that reduction always culminates in two-layer glands and not in one-layer glands. This finding suggests that the one-layer state in the Ninurta-Chamaesaura-Pseudocordylus clade is most probably plesiomorphic, and therefore the ancestral state at the Cordylidae and Cordylinae nodes. Given the observed relationship between type of generation gland and body armour, this finding would suggest that the most recent common ancestor of the Cordylidae was lightly armoured.

How does a viviparous semifossorial lizard reproduce? Ophiodes intermedius (Squamata: Anguidae) from subtropical climate in the Wet Chaco region of Argentina

The best predictors of reproductive patterns are commonly associated with climate factors, but evolutionary history also plays an important role. The semifossorial and viviparous lizard Ophiodes intermedius from the Wet Chaco region of Argentina showed an annual cycle with asynchrony between males and females and an unusual pattern for subtropical climates, with vitellogenesis beginning in autumn, ovulation and copulation in spring, and births occurring in summer. Males exhibited annual variation of testicular size associated with spermatogenic activity, reaching their maximum gonadal activity in late summer (March), but sperm storage in the epididymis and/or deferent duct occurred throughout the year. Females showed an extended reproductive cycle beginning in mid-autumn (May) with vitellogenesis and finishing with births from late spring to mid-summer (December to February). Litter size varied from 4 to 9 offspring. Females reached sexual maturity at a larger snout-vent length and, overall, showed greater body size than males, while males exhibited larger heads than females. Fat body cycles indicated that females use lipid reserves to support vitellogenesis and embryo development, while males allocate lipid resources to the search for females, courtship and copulation rather than to gametogenesis. Ophiodes intermedius differed from other species of the genus in litter size, gestation period, timing of birth and the minimum size at sexual maturity, probably as a result of the influence of ecological, historical and phylogenetic factors.

Reproductive biology of the Amazon Lava Lizard (Tropidurus torquatus) from the Wet Chaco of Corrientes (Argentina): congeneric comparisons of ecotypic and interspecific variations

Herein we describe the reproductive biology of a population of the Amazon Lava Lizard (Tropidurus torquatus (Wied-Neuwied, 1820)) from Corrientes, northeastern Argentina (Wet Chaco). We describe the male and female reproductive cycles, minimum body size for adults, reproductive output, mean relative clutch mass, fat body cycles, and sexual dimorphism. Our results were compared with data on the reproductive biology of Brazilian populations of T. torquatus and congeneric species. In Corrientes, males of T. torquatus exhibited a continuous reproductive cycle, but with annual variation of testicular parameters associated with spermatogenic activity. In contrast, females were reproductive only from winter to summer (July–February), laying at least two clutches each of six eggs, on average, per reproductive season. The relative clutch mass and egg size values in Corrientes were the highest reported for the species. The annual cycle of energy storage (as fat bodies) was inversely correlated with reproductive activity in both sexes. Males differed from females in snout–vent length, head size, interlimb length, and tail length. We observed interpopulational differences in relative clutch mass, egg volume and mass, incubation period and hatching time, and the minimum body size for sexual maturity probably as a result of phenotypic plasticity or adaptation to local environmental conditions and likely both.