Form-function relationships underlie rapid dietary changes in a lizard.

Macroevolutionary changes such as variation in habitat use or diet are often associated with convergent, adaptive changes in morphology. However, it is still unclear how small-scale morphological variation at the population level can drive shifts in ecology such as observed at a macroevolutionary scale. Here, we address this question by investigating how variation in cranial form and feeding mechanics relate to rapid changes in diet in an insular lizard (Podarcis siculus) after experimental introduction into a new environment. We first quantified differences in the skull shape and jaw muscle architecture between the source and introduced population using three-dimensional geometric morphometrics and dissections. Next, we tested the impact of the observed variation in morphology on the mechanical performance of the masticatory system using computer-based biomechanical simulation techniques. Our results show that small differences in shape, combined with variation in muscle architecture, can result in significant differences in performance allowing access to novel trophic resources. The confrontation of these data with the already described macroevolutionary relationships between cranial form and function in these insular lizards provides insights into how selection can, over relatively short time scales, drive major changes in ecology through its impact on mechanical performance.

Is the whole more than the sum of its parts? Evolutionary trade-offs between burst and sustained locomotion in lacertid lizards.

Trade-offs arise when two functional traits impose conflicting demands on the same design trait. Consequently, excellence in one comes at the cost of performance in the other. One of the most widely studied performance trade-offs is the one between sprint speed and endurance. Although biochemical, physiological and (bio)mechanical correlates of either locomotor trait conflict with each other, results at the whole-organism level are mixed. Here, we test whether burst (speed, acceleration) and sustained locomotion (stamina) trade off at both the isolated muscle and whole-organism level among 17 species of lacertid lizards. In addition, we test for a mechanical link between the organismal and muscular (power output, fatigue resistance) performance traits. We find weak evidence for a trade-off between burst and sustained locomotion at the whole-organism level; however, there is a significant trade-off between muscle power output and fatigue resistance in the isolated muscle level. Variation in whole-animal sprint speed can be convincingly explained by variation in muscular power output. The variation in locomotor stamina at the whole-organism level does not relate to the variation in muscle fatigue resistance, suggesting that whole-organism stamina depends not only on muscle contractile performance but probably also on the performance of the circulatory and respiratory systems.

Genetic divergence among sympatric colour morphs of the Dalmatian wall lizard (Podarcis melisellensis).

If alternative phenotypes in polymorphic populations do not mate randomly, they can be used as model systems to study adaptive diversification and possibly the early stages of sympatric speciation. In this case, non random mating is expected to support genetic divergence among the different phenotypes. In the present study, we use population genetic analyses to test putatively neutral genetic divergence (of microsatellite loci) among three colour morphs of the lizard Podarcis melisellensis, which is associated with differences in male morphology, performance and behaviour. We found weak evidence of genetic divergence, indicating that gene flow is somewhat restricted among morphs and suggesting possible adaptive diversification.

Characterization of polymorphic microsatellite markers in the Dalmatian wall lizard Podarcis melisellensis (Squamata: Lacertidae).

We describe polymerase chain reaction primers and amplification conditions for 13 highly polymorphic microsatellite DNA loci isolated from the Dalmatian wall lizard, Podarcis melisellensis. The number of alleles per locus ranged from 12 to 41, with levels of observed heterozygosity between 0.62 and 0.94. Most of these loci were successfully cross-amplified in the closely related species P. sicula, but levels of polymorphism were always lower.

Further evidence of the existence of oviparous populations of Lacerta (Zootoca) vivipara in the NW of the Balkan Peninsula.

The lizard Lacerta (Zootoca) vivipara, which is viviparous in the greatest part of its distribution range, has however some oviparous populations on the southern margin of its range. The present study aimed at determining the reproductive mode and the ATA (aspartate transaminase) enzyme characteristics of four populations in Slovenia and one population in Croatia. The Slovenian females studied here presented an oviparous reproductive mode which strongly resembled those observed in the oviparous populations of south-western France and north-western Spain. Our electrophoresis analyses revealed the existence of two distinct alleles, ATA-150 and ATA-200, in the oviparous populations of Slovenia. These alleles were identical to those observed in the French and Spanish oviparous group and were distinct from the allele ATA-100 characterizing the viviparous populations that we had previously studied. Although we did not study the reproductive mode of Croatian females, the allele ATA-200 observed in one population of Croatia strongly suggested that this population might also be oviparous.

A royal jelly as a new potential immunomodulator in rats and mice.

In order to study a possible immunomodulatory effect of the royal jelly (RJ) secreted by mandibular and hypopharingeal glands of the worker honeybee (Apis mellifera Linné.) we have used a well established rodent model. The CBA mice were given s.c. 0.1 ml of RJ, 7 days before, or immediately after, the immunization with sheep red blood cells (SRBC). The Y59 rats received i.m. 0.4 ml or i.v. 0.025 ml of RJ once or twice at 7 day intervals. Serum levels of total proteins and immunoglobulins in the rats that received RJ once or twice within a 2-week-period were significantly lower (P < or = 0.05) as compared with the nontreated animals. In mice which were immunized with 4 x 10(8) of SRBC 7 days after the application of RJ the number of plaque forming splenocytes was significantly higher (P < or = 0.05) than that in the controls. Both the weight of inguinal lymph node and the number of peripheral blood lymphocytes were increased (P < or = 0.05) in RJ-treated mice 3 or 5 days after the immunization, respectively. Neutrophils were decreased (P < or = 0.05) in the mice that were killed 5 or 10 days after the RJ treatment. Overall these results indicate that RJ exhibited immunomodulatory properties by stimulating antibody production and immunocompetent cell proliferation in mice or depressing humoral immune functions in rats. Both phenomena, though species-related in this model, could probably be reversed by changing the dose or the route of RJ application.