Eggs of wall lizards (Podarcis muralis) were incubated at three temperatures approaching the upper limit of viability for embryonic development in this species (26, 29, and 32°C) to assess the influence of temperature on various aspects of hatchling phenotype likely affecting fitness. The thermal environment affected size and several morphometric characteristics of hatchling lizards. Hatchlings from eggs incubated at 32°C were smaller (snout‐vent length, SVL) than those from 26 and 29°C and had smaller mass residuals (from the regression on SVL) as well as shorter tail, head, and femur relative to SVL. Variation in the level of fluctuating asymmetry in meristic and morphometric traits associated with incubation temperatures was quite high but not clearly consistent with the prediction that environmental stress associated with the highest incubation temperatures might produce the highest level of asymmetry. When tested for locomotor capacity in trials developed at body temperatures of 32 and 35°C, hatchlings from the 32°C incubation treatment exhibited the worst performance in any aspect considered (burst speed, maximal length, and number of stops in the complete run). Repeated measures ANCOVAs (with initial egg mass as covariate) of snout‐vent length and mass of lizards at days 0 and 20 revealed significant effects of incubation temperature only for mass, being again the hatchlings from eggs incubated at 32°C those exhibiting the smallest final size. All together, our results evidenced a pervasive effect of thermal regime during incubation (and hence of nest site selection) on hatchling phenotypes. However, incubation temperature does not affect hatchling phenotypes in a continuous way; for most of the analysed traits a critical threshold seems to exist between 29 and 32°C, so that hatchlings incubated at 32°C exhibited major detrimental effects. J. Exp. Zool. 286:422–433, 2000. © 2000 Wiley‐Liss, Inc.

Research on life-history traits of squamate reptiles has focused on North American species, while Asian taxa have been virtually ignored. In order to understand general patterns in reptile life histories, we need a broader data base. Our study on the slender-bodied lacertid lizard Takydromus septentrionalis provides the first detailed information on factors responsible for intraspecific variation in reproductive output and life history in a Chinese reptile. Clutches of recently collected lizards from five widely separated localities in China revealed major divergences in female body size at maturation, mean adult female body size, body condition after oviposition, size-adjusted fecundity, relative clutch mass, and mass and shape of eggs. Most of these geographical differences persisted when the same groups of females were maintained in identical conditions in captivity. Additionally, reproductive frequency during maintenance under laboratory conditions differed according to the animals' place of origin. Thus, the extensive geographical variation in reproductive and life-history traits that occurs within T. septentrionalis is exhibited even in long-term captives, suggesting that proximate factors that vary among localities (local conditions of weather and food supply) are less important determinants of life-history variation than are intrinsic (presumably genetic) influences. The maternal abdominal volume available to hold the clutch may be one such factor, based on low levels of variation in Relative Clutch Mass among populations, and geographical variation in the position of trade-off lines linking offspring size to fecundity.

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Antibiotic pollutants were ubiquitous in various environmental compartments of Shandong province of China. Risk estimates indicated a potential for the measured levels of enrofloxacin, levofloxacin and ciprofloxacin in waste water to pose an ecological risk for resistance selection, and further studies are needed to validate this finding. The investigated antibiotics did not appear to pose an appreciable direct human health risk from environmental exposure through drinking water or vegetables consumption. However, they might still pose a risk for resistance development.

The numbers and sizes of eggs produced by adult females ultimately determine the viability of populations, as well as the evolutionary fitness of the females themselves. Despite an enormous amount of literature on the adaptive significance of fecundity variation within and among populations, simpler questions-such as the proximate mechanisms by which a female determines her clutch size-have attracted less attention. Our surgical manipulations show that the amount of space available to hold eggs within a female's abdomen influences her total reproductive allocation, enabling her to flexibly modify her reproductive output as she grows larger.

To understand how nest temperatures influence phenotypic traits of reptilian hatchlings, the effects of fluctuating temperature on hatchling traits must be known. Most investigations, however, have only considered the effects of constant temperatures. We incubated eggs of Takydromus septentrionalis (Lacertidae) at constant (24 degrees C, 27 degrees C, 30 degrees C and 33 degrees C) and fluctuating temperatures to determine the effects of these thermal regimes on incubation duration, hatching success and hatchling traits (morphology and locomotor performance). Hatching success at 24 degrees C and 27 degrees C was higher, and hatchlings derived from these two temperatures were larger and performed better than their counterparts from 30 degrees C and 33 degrees C. Eggs incubated at fluctuating temperatures exhibited surprisingly high hatching success and also produced large and well-performed hatchlings in spite of the extremely wide range of temperatures (11.6-36.2 degrees C) they experienced. This means that exposure of eggs to adversely low or high temperatures for short periods does not increase embryonic mortality. The variance of fluctuating temperatures affected hatchling morphology and locomotor performance more evidently than did the mean of the temperatures in this case. The head size and sprint speed of the hatchlings increased with increasing variances of fluctuating temperatures. These results suggest that thermal variances significantly affect embryonic development and phenotypic traits of hatchling reptiles and are therefore ecologically meaningful.

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