The eastern fence lizard, Sceloporus undulatus, is a broadly distributed polytypic species. We surveyed allozyme variation with the goal of generating an intraspecific phylogeny to evaluate the current classification of the species. We electrophoretically assayed 24 loci from 12 populations of S. undulatus, which comprised 6 of the 11 recognized subspecies, 3 additional species of Sceloporus (S. occidentalis, S. virgatus, and S. woodi), and an outgroup taxon, S. clarki. Out of the 24 loci, 14 loci were variable. Phylogenetic analyses using distance, likelihood, and parsimony resulted in trees that were inconsistent with current subspecific designations. Three species of Sceloporus (S. occidentalis, S. virgatus, and S. woodi) arose within S. undulatus. Two major lineages of populations of S. undulatus were identified: (1) a midwestern grasslands group that includes the population from Missouri, and (2) various populations from the eastern woodlands and western canyonlands. The subspecies S. u. hyacithinus and S. u. undulatus are polyphyletic, whereas S. u. garmani and S. u. tristichus are paraphyletic. No fixed allele differences were observed among the populations of S. undulatus, or among the other species of Sceloporus. Our results indicate that the present subspecies designations do not portray patterns of evolutionary relatedness and require re-evaluation.

We determined the overall karyotypic structure, positions of NORs, as well as the distribution of constitutive heterochromatin for Epipedobates flavopictus, E. trivittatus, E. femoralis, and E. hahneli. Despite a conserved chromosome number (2N = 24), morphological differences were seen in the group of small chromosomes. Epipedobates femoralis presented a distinctive karyotype compared to the other species analyzed. All species examined had NORs on different chromosomes. The C-banding pattern showed a considerable variation among the species. Epipedobates flavopictus is remarkably different from the others in possessing only centromeric C-bands. The distribution of heterochromatin varied among species and seems to evolve as a species-specific trait. We suggest that NOR location variability indicates that some rearrangement mechanisms have taken place during the evolutionary history of this group, because Dendrobatidae is considered a monophyletic taxon. We do not discard that some general pattern in either C-band or NOR location, or both, may emerge when more species of this genus are analyzed.

We evaluated five species of the genus Ambystoma in laboratory aquaria to quantify the effect of other larvae on microhabitat use and activity. We studied microhabitat use by partitioning containers into microhabitats that either contained or lacked refuges and recorded movement to determine activity. All five species altered microhabitat preferences and activity levels when they shared tanks with larvae of most species. The smallest species (A. laterale and A. maculatum) spent the most time in the vegetated chamber, used the vegetated chamber more often, and decreased activity in the presence of potential predators. When species were paired, both species usually changed their activity and use of microhabitat in opposite directions. These behaviors may be important in maintaining coexistence among species by reducing interspecific aggression and intraguild predation.

Mountain yellow-legged frogs (Rana muscosa) at high elevations of the Sierra Nevada must obtain enough food during summer to survive 7–9 winter months when their aquatic habitats are frozen and food is presumably unavailable. Adults of R. muscosa prey on a variety of organisms, including aquatic and terrestrial invertebrates and anuran larvae. To determine if anuran larvae influence the condition, distribution, and survival of adults of R. muscosa, we assessed body condition (variation from the expected mass for given length) and distribution of R. muscosa in relation to abundance and distribution of larval Hyla regilla, Bufo canorus, and Bufo boreas. Using three years of mark-recapture data, we found that abundance of larval H. regilla in a water body was positively correlated with the condition of R. muscosa. Moreover, R. muscosa had higher relative mass (W_r) values in areas with other anuran larvae than in areas with no other amphibian species. High W_r values significantly increased the probability of recapturing frogs in following years. Using surveys of over 1700 lakes and ponds in the John Muir Wilderness and Kings Canyon National Park, we also found that the presence of larval H. regilla or Bufo in a water body was a significant indicator of the presence of adults of R. muscosa after accounting for significant habitat and isolation variables. These findings taken together suggest that some adults of R. muscosa actively seek out water bodies with other anuran species during the critical summer months and that the anuran larvae provide a nutritious food source that increases the body condition and, therefore, survival of the frogs.

I performed a displacement experiment with free-ranging adults of Anolis cristatellus, a tropical lizard species whose year-around space-use requirements are limited to small arboreal territories. Because A. cristatellus is a relatively sedentary species, selection for a generalized spatial orientation would seem unlikely. However, more than two-thirds of 25 lizards returned to home territories within an average of 3 d when relocated 11–62 m (equivalent to 2–26 territory diameters) to presumably unfamiliar release localities. Within the conditions of the study, there was no significant effect on returning success by displacement distance, sex, or body size. The returning performance of A. cristatellus supported two inferences. First, considering the costs and risks of traveling through unfamiliar habitat, returning to a specific location from a distant release point indicated the relative importance of a familiar home range to survival and reproduction by both sexes. Second, returning performance indicated that A. cristatellus can at least generalize between familiar and unfamiliar views of landmarks to determine a novel route between its displaced site and its home locality (i.e., pilotage). I suggest that the spatial ability demonstrated by A. cristatellus has not been selected in the context of “homing,” a phenomenon absent to this non-ranging species. Instead, the spatial cognition demonstrated by pilotage could be selected as a social mechanism, whereby a resident can spatially place itself, mates, competitors, and predators relative to its three-dimensional home range. By avoiding surprise, a resident who can anticipate encountering specific individuals at particular localities within its home range will gain a social advantage.

I observed the agonistic and display behavior of the wandering salamander (Aneides vagrans: Plethodontidae) from Vancouver Island, British Columbia, Canada, in 90 staged encounters of 42 individuals of both sexes. Behavioral patterns were similar to those of other plethodontids, and some patterns, such as snout raise, snout-pressing, holding-down, and circle pattern, appear to be unique to the genus. Presumed marking behavior, including chin-rubbing and vent-rubbing, were also seen. Aggressive behaviors recorded for other species of Aneides, including grip, snapping, and bite-hold, were not observed in A. vagrans. The frequency of aggressive behavior was low compared to other plethodontid species in laboratory trials. Agonistic behavior occurred in only 27.7% of encounters; biting occurred in only 2.2%.

I conducted experiments using naturally established neighborhoods of Anolis sagrei to examine interactions between neighboring territorial males. I observed the behavior of groups of lizards before and after the removal of one lizard from the group. I measured space use using x and y coordinates of a 20 × 20 m grid. Focal lizards moved farther from the former resident's activity area center following his removal from the territory. Both neighbors and non-neighbors took over the newly vacated territories, suggesting that some neighbors were able to gain space. The behavioral display patterns of focal lizards did not change following the removal. These data indicate that neighboring males may pose a significant threat to territorial residents by taking space and resources. Additionally, these data provide no evidence that removal of one resident causes general social instability that harms neighbors. These findings have theoretical implications for studies of the “dear enemy” phenomenon and other relationships that are based on social contexts found in territorial neighborhoods.