Lee A. Fitzgerald

The importance of phylogenetic scale in tests of Bergmann's and Rapoport's rules: lessons from a clade of South American lizards

We tested for the occurrence of Bergmanns rule, the pattern of increasing body size with latitude, and Rapoports rule, the positive relationship between geographical range size and latitude, in 34 lineages of Liolaemus lizards that occupy arid regions of the Andean foothills. We tested the climatic‐variability hypothesis (CVH) by examining the relationship between thermal tolerance breadth and distribution. Each of these analyses was performed varying the level of phylogenetic inclusiveness. Bergmanns rule and the CVH were supported, but Rapoports rule was not. More variance in the data for Bergmanns rule and the CVH was explained using species belonging to the L. boulengeri series rather than all species, and inclusion of multiple outgroups tended to obscure these macroecological patterns. Evidence for Bergmanns rule and the predicted patterns from the CVH remained after application of phylogenetic comparative methods, indicating a greater role of ecological processes rather than phylogeny in shaping the current species distributions of these lizards.

Abiotic correlates of anuran calling phenology: the importance of rain, temperature, and season

ABSTRACT We surveyed anuran calls nightly at eight ponds in eastern Texas from 1 January 2001 through 31 December 2002. Air temperatures and daily rainfall also were recorded for each of the sites. Eastern Texas contains a diverse temperate anuran fauna and a climate that provides a range of conditions for anuran reproduction. During our study, we measured air temperatures that fluctuated seasonally with extremes from 0 to 29 C at 2100 h. We found rainfall to be generally abundant with occasional flooding events, however, prolonged periods of no precipitation were also observed. Given the level of anuran diversity and the amount of seasonal variation in temperature and rainfall in our temperate climate we expected to find a variety of breeding strategies. Results from our analyses did indeed suggest five basic breeding strategies based on anuran calling: (1) breeding within a predictable season (summer) independent of local weather patterns; (2) breeding opportunistically within a predictable season (summer) dependent on local rainfall; (3) breeding opportunistically within a predictable season (winter) dependent on local temperature; (4) breeding opportunistically dependent on local flood level rainfall events; (5) breeding opportunistically year round dependent on local temperature in the winter and local rainfall in the summer.

Competition, predation, and the distributions of four desert anurans

Several studies have shown that larval competition and susceptibility to predation affect distributions of amphibian assemblages across ephemeral and perennial habitats. However, few studies have examined mechanisms affecting distribution patterns and site use of anurans adapted to highly ephemeral habitats. This study examines hypotheses about competition and predation as mechanisms creating non-overlapping patterns of site use in four anurans that breed in highly ephemeral habitats: Scaphiopus couchii (Couchs spade-foot toad), Gastrophryne olivacea (narrow-mouthed toad), Bufo speciosus (Texas toad), and Bufo punctatus (red-spotted toad). These four anurans showed a significantly nonrandom pattern of co-occurrence. Only 12% of 95 ephemeral breeding sites surveyed were occupied by more than one species. We tested the hypotheses that non-overlapping use of breeding sites was due to activity rates of their tadpoles that in turn reflect their competitive ability and susceptibility to predation. Tadpoles of S. couchii were significantly more active and more susceptible to predation than were tadpoles of G. olivacea, B. speciosus, and B. punctatus. The masses of G. olivacea, B. speciosus, and B. punctatus were less when they were reared with S. couchii, demonstrating the possible competitive dominance of S. couchii. These results suggest that the competitive ability of S. couchii may play a role in excluding G. olivacea, B. speciosus, and B. punctatus from very ephemeral breeding sites, and that susceptibility to predation could play a role in excluding S. couchii from breeding sites of longer duration that are more likely to be colonized by aquatic predators.

The trade in native and exotic turtles in Texas

Abstract There are growing concerns among conservationists that commercial trade in many species of wild-caught turtles may not be sustainable. Little information on the turtle trade and its impact on populations is available at the national level, and there are no analyses of the commercial trade in turtles in Texas. To quantitatively describe the turtle trade in Texas, we surveyed government organizations, pet and meat establishments, reptile expositions, zoos, aquariums, and Texas herpetological societies by mail, phone calls, or visits. We used the United States Fish and Wildlife Service’s (USFWS) Law Enforcement Management Information System (LEMIS) database to quantify the turtle trade in Texas from 1995-2000. Five turtle species accounted for 99% of collections from the wild in 1999, but at least 69 native and exotic species were available in the pet and meat markets. Nonnative species were exported from Texas, implying that they were either imported from other states and re-exported from Texas or were bred in captivity. Unfortunately, the current national wildlife trade monitoring system does not distinguish between export and re-export, making it difficult to fully understand wildlife trade patterns. Turtle populations in general were susceptible to overexploitation. We recommend that populations of commercially exploited turtles be monitored to build databases required for establishing harvest quotas and size limits. Methods used in this study could be implemented by other states to monitor their turtle trade.

The Reproductive Cycle and the Size at Maturity of Tupinambis rufescens (Sauria: Teiidae) in the Dry Chaco of Argentina

The reproductive patterns of Tupinambis rufescens have not been described. The present study had three objectives: (1) to describe the reproductive and fat body cycles of T. rufescens from our study site in the dry chaco of Argentina; (2) to elucidate and analyze the distribution of sizes at which female T. rufescens reach sexual maturity; and (3) to discuss the conservation implications of the repro- ductive cycle of T. rufescens. Oviductal width increased significantly after females reached 320 mm SVL, and we presumed the increase was due to stretching of the oviducts in females that had been gravid. Seventy-eight percent of the females >319 mm snout-vent length (SVL) and 84.3% > 349 mm SVL possessed oviducts > 3.5 mm wide, our criterion for indicating a female had reproduced, while only 6.9% of the females 3.5 mm wide were convoluted, while all the narrower oviducts were straight or striated. The reproductive and fat body cycles of T. rufescens at our study site were characteristic of lizards from seasonal environments, and appeared closely tied to the onset of the rainy season and increasing spring temperatures. Mature females exhibited significantly longer ovaries in No- vember than in other months, and nesting was observed in November and December. The average clutch size was 21.4, and the smallest female we found with eggs was 330 mm SVL. Testis mass was significantly greater in November than in other months, and declined slightly throughout the activity season. Some gonadal development in males presumably occurred while the lizards were inactive during winter. Fat body volume was tightly linked to the gonadal cycle of both males and females. Females apparently allocated fat stores to developing eggs, while males probably used fat stores for spermatogenesis or for meeting the energetic demands of mate seeking. Large numbers of Tupinambis are exploited for their skins, and this study provides life history infor- mation needed to develop scientifically-based management plans, for example, the size distribution of reproductive females, the timing of reproduction, and clutch size. Based on our analyses, management strategies aimed at harvesting adults and subadults could be evaluated because the proportions of the harvest comprised of adults can be reliably determined. We recommend that strategies aimed at classifying harvests according to adults and subadults use 350 mm SVL as a cut-off point for mature females.

Molecular Phylogenetics and Conservation of Tupinambis (Sauria: Teiidae)

examined genetic or morphological variation in these lizards. We sequenced parts of the mitochondrial cytochrome b (300bp) and ND4 (375bp) genes and examined this variation in light of morphological characters traditionally used to identify these species. DNA sequences provided a preliminary view of intraspecific and interspecific variation and were used to explore evolutionary relationships among 17 individuals representing T. merianae, T. rufescens, and T. duseni from Paraguay, and T. longilineus and T. teguixin from Roraima, Brazil, and Cuyabeno, Ecuador. Kentropyx viridistriga, Ameiva ameiva, and Cnemidophorus ocellifer were included as outgroups. Maximum-parsimony and neighbor-joining analyses revealed two distinctive groups within Tupinambis; a northern South American and Amazonian clade (T. teguixin, T. longilineus) and a clade (T. duseni, T. rufescens, and T. merianae) that is distributed primarily south of Amazonia. Although genetically similar and previously considered synonymous with T. rufescens, T. duseni is morphologically distinct based on squamation, coloration, and morphometrics. This incongruence between the molecular data and morphology suggests that T. duseni and T. rufescens may have undergone extensive and recent morphological evolution or there has been introgression of mitochondrial DNA between these species. Sequence divergence between T. teguixin from Brazil and Ecuador was similar to that found between T. rufescens and T. merianae and may indicate these T. teguixin populations are not conspecific. The T. teguixin clade was sister to T. longilineus. These findings, combined with the largescale commercial exploitation of the genus, suggest an urgent need to address geographic variation and the systematics of species of Tupinambis.

Morphological correlates of locomotor performance in hatchling Amblyrhynchus cristatus

Previous studies of locomotor performance from a variety of perspectives often assumed that speed and limb length were strongly correlated. Despite support of this assumption from biomechanical models, few empirical studies have demonstrated a significant relationship between measures of locomotor capacity, such as maximum velocity, and length of the hindlimb at either the inter- or intra-specific level. We examined whether one measure of locomotor performance, maximum velocity, correlates with body size and elements of the hindlimb in hatchling marine iguanas (Amblyrhynchus cristatus). Larger hatchlings ran faster. Removing the effects of body size revealed that relative lengths of the tibia and hindfoot correlated with size-adjusted maximum velocity. Individuals with relatively long tibia and short pes were relatively faster than individuals with short tibia and long pes. Functional morphological analyses predict that femur length should correlate with maximum velocity. However, our analyses failed to support this prediction. Because hatchling marine iguanas exploit relatively open habitats, the relationship between maximum velocity and limb morphology may be interpreted as an adaptation enhancing escape from predators.

Distance Sampling Underestimates Population Densities of Dune-Dwelling Lizards

Abstract Distance sampling methods to estimate population densities are in wide use; however, this method may not be suitable for certain species or in certain habitats. Although validation of population estimates derived from distance sampling is necessary to determine the reliability of population estimates, validation is lacking in most studies. We measured densities of six lizard species, with particular emphasis on the endemic Dunes Sagebrush Lizard (Sceloporus arenicolus) at 14 sites throughout the range of this species in the Mescalero Sands ecosystem in southeastern New Mexico. We tested the accuracy of distance sampling by comparing results from 238 distance line transects to densities measured in 20 total removal plots. Density estimates from the distance sampling method (N  =  238 transects) for S. arenicolus and all lizard species combined were 4.6 lizards/ha and 26.14 lizards/ha, respectively. Density estimates from the total removal plots (N  =  20) were 30.0 lizards/ha for S. arenicolus and 85.0 lizards/ha for all lizard species combined. It is clear that, even in the relatively open shinnery oak sand dune habitat, distance sampling methods were not reliable and underestimated the densities of lizards. The disparity in density estimates from distance sampling versus total removal plots was caused by violation of the assumption of perfect detection of individuals on the transect line. Individuals that were unavailable for detection greatly influenced the density estimates. Because of the difficulty in correcting for biases, we suggest that distance sampling is not an appropriate sampling method for estimating densities of lizards.

Population Variation in Dune-Dwelling Lizards in Response to Patch Size, Patch Quality, and Oil and Gas Development

Abstract We studied relationships between quality and quantity of habitat and conversion of land to caliche roads and well pads associated with oil and gas development. We asked how these factors affected abundance of dune-dwelling lizards, with emphasis on a habitat specialist, the dunes sagebrush lizard Sceloporus arenicolus. Open depressions in dune complexes are a critical landscape feature for S. arenicolus, and extensively used by all species; thus, size and total area of open depressions in a study site were our measures of habitat quality and quantity. There were significant differences in habitat quality among sites, and habitat quality and quantity were correlated significantly. Abundances of all lizards, including S. arenicolus, varied significantly among sites and this variation could be explained by amount of habitat at a given site. Relationships between oil and gas development, quantity and quality of habitat, and abundances of lizards likely occur on different spatial scales constraining our ability to detect direct effects of oil and gas development alone. Our research is the first to investigate effects of oil and gas development on an assemblage of dune-dwelling lizards.

Disassembly of a dune‐dwelling lizard community due to landscape fragmentation

Landscape fragmentation alters patterns of landscape structure that affect quality and configuration of habitats, and disrupts population dynamics and persistence of species. Community disassembly, a process of community change due to nonrandom species losses and declines, is occurring worldwide as a result of landscape fragmentation, habitat loss, and habitat degradation. We carried out a comparative study at 27 trapping sites designed to characterize how fragmentation affects community structure in a dune-dwelling lizard community. Lizard communities in non-fragmented sites demonstrated nested community structure. Conversely, lizard communities at sites fragmented by roads and well pads from oil and gas development had consistently lower abundance of two species, and demonstrated random community structure. Species loss and lower abundance of species at fragmented sites suggested a pattern of community disassembly. The dunes sagebrush lizard (Sceloporus arenicolus), an ecological specialist, and the lesser earless lizard (Holbrookia maculata) were present on most non-fragmented sites. However, neither species was present on more than half of the fragmented sites, and their abundances were much lower than on non-fragmented sites. We attributed reduced species diversity on fragmented sites to quantitative differences in landscape configuration compared to non-fragmented sites. Specifically, both size and shape of sand dune blowouts differed between non-fragmented and fragmented sites. Fragmented sites possess more large patches of open sand and barren ground and fewer, smaller, and more dispersed shinnery dune blowouts. Patterns of occurrence and relative abundance suggest S. arenicolus and H. maculata were sensitive to these patch-scale attributes. In this ecosystem, landscape-scale fragmentation appears to influence landscape configuration and community disassembly at the patch-scale. Our findings allow us to disentangle drivers of species loss and enhance our understanding of the processes of community disassembly in fragmented landscapes.