Phylogeography and population structure of the Reevese's Butterfly Lizard (Leiolepis reevesii) inferred from mitochondrial DNA sequences.

Butterfly lizards of the genus Leiolepis (Agamidae) are widely distributed in coastal regions of Southeast Asia and South China, with the Reevese's Butterfly Lizard Leiolepis reevesii having a most northerly distribution that ranges from Vietnam to South China. To assess the genetic diversity within L. reevesii, and its population structure and evolutionary history, we sequenced 1004 bp of cytochrome b for 448 individuals collected from 28 localities covering almost the whole range of the lizard. One hundred and forty variable sites were observed, and 93 haplotypes were defined. We identified three genetically distinct clades, of which Clade A includes haplotypes mainly from southeastern Hainan, Clade B from Guangdong and northern Hainan, and Clade C from Vietnam and the other localities of China. Clade A was well distinguished and divergent from the other two. The Wuzhishan and Yinggeling mountain ranges were important barriers limiting gene exchange between populations on the both sides of the mountain series, whereas the Gulf of Tonkin and the Qiongzhou Strait were not. One plausible scenario to explain our genetic data is a historical dispersion of L. reevesii as proceeding from Vietnam to Hainan, followed by a second wave of dispersal from Hainan to Guangdong and Guangxi. Another equally plausible scenario is a historically widespread population that has been structured by vicariant factors such as the mountains in Hainan and sea level fluctuations.

Does follicle excision always result in enlargement of offspring size in lizards?

An experimental reduction of offspring number has been reported to result in enlargement of offspring size in lizards. We applied the "follicle excision" technique to a lacertid lizard (Takydromus septentrionalis) to examine whether this effect is generalisable to lizards. Of the 82 females that produced 3 successive clutches in the laboratory, 23 females underwent follicle excision after they oviposited the first clutch. Follicle excision reduced clutch size, but did not alter egg size. This result indicates that egg size is not altered during vitellogenesis in T. septentrionalis. Females undergoing follicle excision produced a third clutch (a second post-surgical clutch) as normally as did control females. Females switched from producing more but smaller eggs early in the breeding season to fewer but larger eggs later in the season. Our results indicate that female T. septentrionalis maximize reproductive success by diverting an optimal, rather than a higher, fraction of the available energy to individual offspring. This optimized allocation of the available energy to offspring production explains why follicle excision does not result in enlargement of egg size in this species. Our study provides evidence that an experimental reduction of offspring number does not always result in enlargement of offspring size in lizards.

Influence of incubation temperature on hatching success, energy expenditure for embryonic development, and size and morphology of hatchlings in the oriental garden lizard, Calotes versicolor (Agamidae).

We incubated eggs of Calotes versicolor at four constant temperatures ranging from 24 degrees C to 33 degrees C to assess the effects of incubation temperature on hatching success, embryonic use of energy, and hatchling phenotypes that are likely to affect fitness. All viable eggs increased in mass throughout incubation due to absorption of water, and mass gain during incubation was dependent on initial egg mass and incubation temperature. The average duration of incubation at 24 degrees C, 27 degrees C, 30 degrees C, and 33 degrees C was 82.1 days, 60.5 days, 51.4 days, and 50.3 days, respectively. Incubation temperature affected hatching success, energy expenditure for embryonic development, and several hatchling traits examined, but it did not affect the sex ratio of hatchlings. Hatching success was lowest (3.4%) at 33 degrees C, but a higher incidence of deformed embryos was recorded from eggs incubated at this temperature compared to eggs incubated at lower temperatures. Most of the deformed embryos died at the last stage of incubation. Energy expenditure for embryonic development was, however, higher in eggs incubated at 33 degrees C than those similarly incubated at lower temperatures. A prolonged exposure of eggs of C. versicolor at 33 degrees C appears to have an adverse and presumably lethal effect on embryonic development. Hatching success at 24 degrees C was also low (43.3%), but hatchlings incubated at 24 degrees C did not differ in any of the examined traits from those incubated at two intermediate temperatures (27 degrees C and 30 degrees C). Hatchlings incubated at 33 degrees C were smaller (snout-vent length, SVL) than those incubated at lower incubation temperatures and had larger mass residuals (from the regression on SVL) as well as shorter head length, hindlimb length, tympanum diameter, and eye diameter relative to SVL. Hatchlings from 33 degrees C had significantly lower scores on the first axis of a principal component analysis representing mainly SVL-free head size (length and width) and fore- and hindlimb lengths, but they had significantly higher scores on the second axis mainly representing SVL-free wet body mass. Variation in the level of fluctuating asymmetry in eye diameter associated with incubation temperatures was quite high, and it was clearly consistent with the prediction that environmental stress associated with the highest incubation temperatures might produce the highest level of asymmetry. Newly emerged hatchlings exhibited sexual dimorphism in head width, with male hatchlings having larger head width than females.