Unisexual salamanders present a novel evolutionary phenomenon that has led to many speculations with respect to their origin and persistence. These salamanders do not comply with basic evolutionary theory with respect to any of the factors that guide speciation. Indeed, none of the various unisexual salamanders can be considered a distinct species. I outline the history of the unisexual Ambystoma from their discovery by Clanton in 1934 and attempt to show how our current understanding of the unisexuals has been influenced by discovering new populations and advances in technology.

Prolonged and complex courtship behaviors, involving tactile, acoustic, and visual signals, are common in Neotropical poison frogs (Dendrobatidae). Courtship is an important precursor to mating, but courtship components vary across species. In Brilliant-Thighed Poison Frogs (Allobates femoralis [Boulenger 1883]), males guide females to oviposition sites in a so-called “courtship march.” The courtship duration in A. femoralis is among the longest known in poison frogs. To gain insights into the functions of courtship, we observed 29 courtship events in an A. femoralis population in French Guiana. In addition, we observed multiple courtships of 7 males to assess intra- and interindividual variations in courtship behavior. We recorded temporal, spatial, and behavioral characteristics of courtship and searched for previously deposited clutches in the males' territories. Courtships started in the afternoon and ended on the following morning. During courtship, pairs moved an average of 19 m within an area of about 6 m². Twenty-seven out of 29 courtships (93.1%) resulted in successful oviposition, indicating that females rarely reject males once engaged in courtship. Contrary to previous studies of A. femoralis, the spatial and temporal extent of the courtship march did not correlate with the size of a male's territory. Our results indicate that females do not evaluate male quality during courtship but might need an extended courtship phase to verify territory ownership of the courting male and to stimulate ovulation. The prolonged courtship might also be beneficial for spatial learning by females, allowing them to find clutches again in cases of mate loss. Temporal and spatial characteristics vary considerably within and among individuals, and males do not use the same routes in consecutive courtships. However, they probably show females previous clutches. Several courtship traits in our study population differ from A. femoralis courtship previously described from Peru and Brazil, indicating that dendrobatid courtship is variable among populations.

Identifying resource allocation patterns is fundamental to understanding reproductive investment strategies that maximize maternal fitness. Turtles are useful model organisms for such studies because many species do not invest in postnesting parental care; therefore, variation in maternal investment can be assessed primarily from variation in clutch characteristics. We examined maternal investment patterns in Macrochelys temminckii by measuring reproductive output of captive turtles exposed to similar conditions. Larger females tended to produce larger eggs by mass, but not diameter, and female size and within-clutch variation accounted for 68% of the total variation in egg size. The number of eggs per clutch did not correlate with female body size. Larger females exhibited greater total reproductive effort, however, because total clutch mass positively correlated with female size. Hatchling size increased with increasing egg size, but there was no relationship between female size and hatchling size. There was an effect of female identity on hatchling size independent of female size. Female body condition did not explain any of the variation in clutch, egg, or hatchling characteristics. Clutch size varied more than egg size and, after controlling for female size, we also found evidence of a negative correlation between clutch and egg size. These results indicate that M. temminckii primarily increase maternal investment by producing more eggs rather than bigger eggs. Finally, resource availability affected the number of eggs females produced, but the size of individual eggs might be more influenced by factors related to maternal identity.

Some of the most striking behaviors of animals are displays used in courtship, territorial behavior, and in defense against predators. Among reptiles, lizards exhibit enormous diversity in the stereotyped motion patterns of their bobbing displays. Although the bobbing displays of numerous lizard species have been described to date, those of the Galápagos Lava Lizards (Microlophus spp., Tropiduridae) have received comparatively little attention. Here, we analyze bobbing displays from four of the nine lava lizard species: Microlophus albemarlensis, M. bivittatus, M. grayii, and M. indefatigabilis. Field-recorded displays first were standardized to a common amplitude scale, and attributes of display duration and head amplitude were measured. Next, a discrete Fourier transform (DFT) was computed for each display, and data were gathered on 13 frequency and amplitude variables. Then, we conducted a principal components analysis on the Fourier transform–based variables, and used discriminant function analyses (both standard and permuted) to test the strength of species specificity in display structure. Results showed that displays with simpler structure (M. albemarlensis and M. grayii) were more often correctly assigned to species than were displays with more complex structure (M. bivittatus and M. indefatigabilis). We offer predictions for further tests on the bobbing displays of additional species of Galápagos lava lizards, and suggest that DFT represents a promising tool for the analysis of animal motion displays.

We investigated the importance of ecological and historical effects in structuring a lizard assemblage in a semiarid area of Caatinga habitat. We collected lizards using pitfall traps and active searching; we also collected data concerning microhabitat and diet composition for the lizard species examined. We used null models to test whether or not the community was structured following microhabitat or trophic niches. We also tested whether or not such structure had a historical or ecological origin using canonical phylogenetic ordination and phylogenetic principal component analysis. Gymnodactylus geckoides and Tropidurus hispidus were most generalized in their microhabitat use. Hemidactylus brasilianus and Phyllopezus pollicaris had the greatest numeric niche breadth, whereas P. pollicaris and T. hispidus had the greatest volumetric niche breadth. In contrast, Brasiliscincus heathi and Ameiva ameiva had the smallest numeric and volumetric niche breadths, respectively. The lizard assemblage examined had structure in both microhabitat and trophic niches. We detected phylogenetic conservatism on the basis of spatial niches in the clades Teoidea, Teiidae, and Tropiduridae. In contrast to the predictions of the niche complementarity hypothesis, we found high trophic overlap coupled with low microhabitat overlap for tropidurids. Moreover, spatial niche structure was mainly attributable to historical factors (phylogenetic), whereas ecological factors were more important determinants of trophic niche structure.

The abundance and composition of parasitic faunas are influenced by morphological and environmental characteristics. Environments with distinct climatic characteristics, such as the semiarid Caatinga domain and coastal Restinga ecosystem of Brazil, have particular humidity, rainfall, and temperature conditions that can influence parasitism in lizard communities. We evaluated the effects of geographic distribution and body size on the abundance and composition of endo- and ectoparasites of a lizard species representing each of the habitats: Ameivula ocellifera and A. nigrigula. Body size did not influence parasitic infestations. Both lizard species showed aggregate distribution patterns of the mite Eutrombicula alfreddugesi. Four endoparasite species were found: Oochoristica, Raillietiella sp., Pharyngodon cesarpintoi, and Physaloptera. The principal endoparasites recorded in A. ocellifera and A. nigrigula were heteroxenous parasites, which are usually indirectly ingested by lizards through their diets (mainly arthropods). The discrepancy indices of endoparasite distributions were similar between the two host species, and showed aggregated distribution patterns. Geographic distributions, substrate temperatures, and the interaction between geographic distribution and air and substrate temperatures influenced ectoparasite abundance in both species, although endoparasite abundance was not explained by these variables. Temperature, precipitation, and humidity during the rainy season in both the Caatinga and Restinga habitats affected parasite abundance, distribution, survival, and development, and contributed to the observed variations in parasitic infestation levels in these lizard species.