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Herein is described a new species of leptodactylid frog from Pedra Azul, Municipality of Domingos Martins, State of Espírito Santo, southeastern Brazil. The new species is a member of the genus Megaelosia, and is characterized by large size; fold of fifth toe not reaching outer metatarsal tubercle; snout rounded in dorsal view and slightly protruding in lateral view; tympanum moderately small; finger tips with scutes fused to the subunguis and toe tips with a pair of scutes free of the subunguis; dorsal skin texture smooth; skin of the flanks without large granules; belly and throat predominantly gray with many, small yellow blotches; and distinct bilateral vocal sacs in males. The tadpole is described. The new species is the northern limit for the genus Megaelosia, and reinforces the high endemism and richness of the anuran fauna from Santa Teresa region, State of Espírito Santo, Brazil.
Arrays of wood cover boards are useful tools for studying and monitoring plethodontid salamander populations. However, little is known about the biases inherent in monitoring data collected from such arrays. We used Red-Backed Salamanders, Plethodon cinereus, to test for two potential biases associated with use of wood cover board arrays. First, we tested whether frequent sampling of arrays can cause reduced counts of salamanders, resulting in the appearance of population declines where none exist. Second, we tested whether salamanders found under wood cover boards differed from salamanders found under natural cover objects in terms of sex ratios, stage class ratios, and snout–vent length. We found that sampling cover boards daily substantially reduced salamander counts under cover objects and that this result was pronounced for adults but not for juveniles. We found no decrease in counts with sampling cover boards weekly as compared to sampling every three weeks. With respect to differences between salamanders found underneath cover boards versus natural cover objects, we found that samples from under cover boards contained higher proportions of adults and lower proportions of juveniles and hatchlings than did natural cover objects. This was true in both the spring and fall. There were no differences in sex ratios or in snout–vent length within stage classes for salamanders in cover boards versus natural cover objects. These results suggest that cover boards used for monitoring or for studies of ecology and behavior should be sampled no more than once per week if natural levels of movement and territoriality are desired. Additionally, although cover board arrays may be suitable for tracking relative changes in overall population size, bias among size classes may make cover boards less than ideal tools for studies of salamander demography.
A hallmark trait of the lizard genus Anolis is the presence of remarkable interspecific variation in dewlap color patterns. Yet, considerable intraspecific variation also occurs in many Anolis species. In Florida different populations of the Green Anole (Anolis carolinensis) exhibit red, pink, magenta, and even greenish-gray dewlaps. To date, comparisons of color variation in this species have used subjective techniques based on human color perception. Instead, we used an objective method—reflectance spectrometry—to quantify A. carolinensis dewlap and body color variation along a transect from northeastern to southwestern Florida. Reflectance readings of local vegetation allowed us to calculate contrast of the lizards with their visual backgrounds. By incorporating local ambient light and A. carolinensis spectral sensitivity into additional calculations, we were able to estimate lizard-background contrast from the perspective of the lizards. Results revealed dewlap and dorsum spectra to differ significantly among most of our study populations, as well as between the lizards and background vegetation. Although increased resemblance of a color signal to the illuminating spectrum will increase the signal's broadcast effectiveness, dewlap colors in our study populations did not resemble the ambient light spectra in their habitats. We consider the potential effects of this species' peculiar spectral sensitivity on the evolution of its dewlap coloration and propose that this coloration may represent a selective compromise to the unusually broad range of light habitats in which A. carolinensis is found. Last, the “gray throated” population of southwest Florida proved to be extraordinary, and we devote special attention to discussing aspects of coloration and contrast in this enigmatic population.
In New England, temporary pool-breeding salamanders inhabit terrestrial forested habitats for the majority of the year. Wetland regulations and forestry Best Management Practices rarely consider the upland areas surrounding breeding pools for protection. Those that do, generally establish buffer zones that are insufficient to protect salamander populations. A better understanding of the area requirements and upland habitat preferences of pool-breeding salamanders is needed to develop biologically relevant buffers for conservation. I used radiotelemetry to investigate the postbreeding emigration and terrestrial habitat use of two syntopic mole salamander species. Sixteen adult salamanders (eight Ambystoma jeffersonianum, and eight Ambystoma maculatum) were radiotracked for a mean of 164 days (SE = 5.1). Eleven individuals were tracked to overwintering sites (five A. jeffersonianum, and six A. maculatum). Emigration distances from breeding pool edge varied widely (range = 30–219 m) with a mean of 112.8 m (SE = 19.9) for both species combined. Combining data from this and other studies, a salamander “life zone” that would encompass 95% of the population was calculated, resulting in an area extending 175 m from a pool's edge. Two types of small mammal burrows (deep vertical tunnels, and highly branched horizontal tunnels) were used almost exclusively as terrestrial refuges. In general, Jefferson and Spotted Salamanders used well-shaded, deciduous forest stands with abundant logs and stumps. Their habitat use also showed a strong association with vertical mammal tunnels, suggesting that this resource may be limiting. Biologically defined salamander life zones should be identified as critical wildlife habitat and considered in forest management strategies.
Leptodactylus dantasi Bokermann is redescribed from adult specimens collected in Parque Nacional da Serra do Divisor, State of Acre, Brazil, near the border between the Brazilian state of Acre and Peru. We propose the inclusion of this species in the genus Hydrolaetare. A new diagnostic character observed for the genus is the presence of fringes of fingers, and fringes and webbing of toes, finely serrate; the serrate edge of the fringe and webbing can be keratinized in males, females, and subadults. Hydrolaetare dantasi (Bokermann) is characterized by robust body and limbs, a broad and depressed head, slightly shorter than wide, and long, pointed and basally webbed toes. Hydrolaetare dantasi differs from the only other species in this genus, Hydrolaetare schmidti (Cochran and Goin), mainly by having toes webbed basally (fully webbed in H. schmidti). The advertisement call of H. dantasi is composed of two components; an initial note produced by the impact of the vocal sac against the ground and a second note corresponding to a long whistle of ascending frequency. The initial note is a percussive sound and represents an unusual form of sound emission in anurans; the second note is a vocalization.
We studied the ecology of the lizard Cnemidophorus ocellifer Spix 1825 in the central Brazilian Cerrado. Cnemidophorus ocellifer was active on open ground, in sandy soils and rocky fields, during the hottest hours of the day. Mean body temperatures (37.5°C) were high, relative to sympatric lizard species, and more associated with substrate temperatures than with air temperatures. The thermal ecology of C. ocellifer seems to be tightly associated with an active mode of foraging. Termites were the most important prey, and there was no significant association between head dimensions and prey dimensions. Cnemidophorus ocellifer showed strong sexual dimorphism in body size and shape, with males having larger bodies and head dimensions, and females having longer and thicker bodies. Clutch size averaged 2.1 and was positively correlated with female SVL. Females were reproductively active during the dry season (May to September) and recruitment occurred from July to November. Males were reproductively active throughout the year, peaking from March to August, coinciding with the period of female reproduction. The reproductive cycle in C. ocellifer may be determined by the greater availability of direct sunlight and its physiological effects upon breeding activities, such as courtship and mating, during the dry season.
We provide data on sexual dimorphism, reproductive biology, and mating aggregations of the Argentine Boa Constrictor (Boa constrictor occidentalis), a poorly known, threatened species. Snakes were examined by ultrasound scanning between 1998 and 2001. Adult females were 14% longer and 51% more massive than adult males. Litter size averaged 25.05 and increased significantly with maternal body size. Reproductive activity was seasonal and associated, with vitellogenesis and spermatogenesis occurring during the dry season (April to September). The ratio of reproductive to nonreproductive females was 1:1, suggesting females do not reproduce annually in this population. Reproductive females were in better body condition (mass relative to body length) than nonreproductive females, indicating that a female's initial “decision” to reproduce in any given year may be driven by her body condition (storing enough energy for a long period before expending it on reproduction: “capital breeder”). Aggregated boas were found only during the dry season. The high proportion of solitary reproductive males and the operational sex ratio (male:female, 1.53:1) suggests a system of “prolonged mate-searching polygyny.”
We studied Diamondback Terrapins, Malaclemys terrapin, at Gateway National Recreation Area, New York. We found evidence of nesting terrapins at three locations within the Recreation Area and focused our research on the islands of Jamaica Bay Wildlife Refuge. Female terrapins nested from early June through early August and oviposited at least two clutches per year. Mean clutch size was 10.9 eggs. Nesting activity increased with daily high temperature and high tide. The greatest number of terrapin nests was found in shrubland, dune, and mixed-grassland habitats, but nest densities were higher on a human-made sandy trail and on sandy beaches. We estimate that approximately 2053 nests were oviposited on the largest island in the refuge in 1999. In 1998 and 1999, we counted 1319 and 1840 depredated nests, respectively, throughout the refuge. Raccoons were introduced into Jamaica Bay Wildlife Refuge approximately 20 yr prior to this study. Raccoons depredated 92.2% of nests monitored on the largest island during the 1999 nesting season. We also found the carcasses of adult female terrapins that apparently were killed by raccoons as they came on land to nest. This terrapin population may be undergoing demographic changes as a result of the introduction of raccoons.
We undertook skin-grafting between populations to determine whether Aspidoscelis rodecki originated from single, or multiple, parthenogenetically capable hybrids. We transplanted 292 skin grafts within and between the two most geographically distant populations, considering only grafts in animals surviving more than 45 days. Two hundred fifteen grafts were analyzed. Histocompatibility within (100%) and between (97.9%) populations suggests that A. rodecki was derived from a single, parthenogenetically capable, hybrid.
With nest incubation temperature determining sex in marine turtle hatchlings, sex ratios among populations and intermediate aggregations are likely to exhibit more geographic and temporal variability than for vertebrates with genotypic sex determination. In this study, we examined the sex ratio of an immature Hawksbill Seaturtle (Eretmochelys imbricata) aggregation at Mona Island, Puerto Rico, using serum testosterone level criteria that were validated through laparoscopy in a subset of turtles. Measured serum testosterone for female turtles ranged between 0.32 and 17 pg/ml and for males between 18.2 and 262 pg/ml. Of 120 turtles sampled, 53 individuals were classified as females and 66 as males, with one individual undetermined. The resulting F:M ratio of 0.80:1 is not significantly different from 1:1. This result contrasts with the highly female-biased sex ratios reported from surrounding Caribbean immature hawksbill aggregations, suggesting that the Mona near shore habitat recruits male turtles from a source uncommon to other aggregations.
Stress resulting from an investigator handling or observing subjects can affect the results of field studies. However, effects of such stressors are rarely investigated. In a series of field experiments in southern Florida we examined whether display behavior of territorial male lizards (Anolis sagrei) was affected by length of time between handling and observation, length of time that an observer was present and length of time that subjects were held in bags prior to release in the field. Proportion of headbob displays that were bobbing displays did not differ between periods 1–2 h after release and one day later, nor did it differ between periods 0–1 h and 1–2 h after the first appearance of an observer. Similarly, this proportion did not differ between animals previously held in bags for one night and those held for two nights. Our results contrast with other studies that have shown strong effects of several social factors on the proportion of bobbing displays. Thus, the factors we studied appear unimportant in affecting the display behavior of A. sagrei.
Amphibians use a range of microhabitats as retreat sites to escape adverse climatic conditions. We conducted two outdoor experiments using a brick pile and shallow trays of water containing aquatic vegetation to assess retreat site selection during winter in the endangered frog Litoria aurea. A multivariate habitat model in the first experiment indicated that frogs preferred to rest close to the edges of the brick pile that received afternoon sunlight and in small gaps between bricks, whereas in the second experiment, frogs showed no preference for terrestrial or aquatic habitats. These results suggest that L. aurea is a generalist in winter habitat choice, although resting positions in terrestrial situations are likely related to site aspect, microhabitat, and temperature.
The overlap pattern between the upper and lower secondary temporal scales is an important systematic character in sphenomorphine skinks. The derived condition of the lower secondary temoral overlapping the upper secondary temporal concords with certain aspects of existing taxonomy, geography, and ecology. Partly on the basis of this character, the recently described genus Paralipinia is placed in the synonmy of Scincella.
We examined clinal variation in body size in the Texas Horned Lizard, Phrynosoma cornutum. We used principle component analysis of 10 morphological characters taken from 230 horned lizards from localities between 100°W and 105°W longitude, from central Mexico to southeastern Colorado (23.75°N to 38.09°N latitude). Females (N = 114) and males (N = 116) were treated separately. The first principle component (size) accounted for 68.4% of the variation in males, with a significant decrease in PC1 score with increased latitude (P < 0.0001, R2 = 0.243). In females, the first principle component accounted for 71.9% of the variation, with a significant decrease in PC1 score with increased latitude (P < 0.0001, R2 = 0.306). There was no significant variation in PC1 with longitude (P = 0.388).
Two basic components of overall shape in scincid lizards were examined in 34 representative species: hind limb length and SVL, both relative to head length. In a bivariate plot of the total available morphological space, only 46% was occupied. Six species that represent the boundaries of the occupied morphological space include a climber on rounded boulders separated by precipitous interstices; a secretive litter-dweller; a bulky, slow moving omnivore; a sand walker/swimmer, and two limbless species. The unoccupied spaces in the total available morphological space represent areas where relative SVL may become too short to support sufficient body curvature in locomotion and where relative limb length may become too long to be supported by the body width. The mean number of presacral vertebrae is a strong proxy for a species' relative SVL (elongation).
Although there are many accounts of the diversity of algae consumed by anuran larvae, growth and digestive responses of tadpoles fed algae have been poorly studied. In this study, growth rates and digestive abilities of larval bullfrogs (Rana catesbeiana) fed monospecific algal diets were investigated. The four algal species used in feeding trials were Selenastrum capricornutum, Microcystis incerta, Anabaena flos-aquae, and Ulothrix coniferricola. The filamentous blue-green alga Anabaena flos-aquae was the only alga that promoted growth in tadpoles and was digested more thoroughly than the other algae. Ability of tadpoles to digest nuisance, bloom-forming algae such as Anabaena has important implications in freshwater resource management. Such results also contribute to a better understanding of the roles tadpoles play in nutrient cycling, their potential to combat eutrophication, and their influence on primary productivity in freshwater ecosystems.
We analyzed geographic variation in external morphology of the endemic Baja California Nightsnake, Eridiphas slevini. Recently, the subspecies from Isla San Marcos (Eridiphas slevini marcosensis) was elevated to specific status based on the original description of only two specimens. Our results reveal complete overlap in characters used to diagnose Eridiphas marcosensis. Thus, we recognize only one species: Eridiphas slevini. Previously observed variation is explained by a latitudinal trend, with females attaining a higher ventral-scale count at the northern end of the species range. We also examined museum specimens for stomach contents and review the literature for dietary records of this rare snake.
We compared behavioral responses of larvae of three Pacific Northwest anurans from different hydroperiods to water borne cues of native and introduced predators. Two native anurans (Pacific Treefrog, Pseudacris regilla, and Northern Red-Legged Frog, Rana aurora aurora) and introduced Bullfrogs (Rana catesbeiana) responded to water conditioned by native Redside Shiners (Richardsonius balteatus) by increasing refuge use. The larvae of the two native anurans differed in their response to introduced predator cues. Rana aurora aurora, which occur in temporary and permanent waters, responded to both introduced Bluegill Sunfish (Lepomis macrochirus) and introduced Crayfish (Procambarus clarkii). Pseudacris regilla, which occur primarily in temporary ponds, did not respond to water borne cues from either introduced predator. The broader responses of R. a. aurora may indicate greater behavioral plasticity or more exposure to novel predators than experienced by P. regilla. Larvae of introduced R. catesbeiana responded strongly to cues from two fish native to the Pacific northwest but did not alter behavior in response to any of five potential predators with which they coexist in their native range. Fish that occur with R. catesbeiana in their native range generally find Bullfrog larvae unpalatable. This pattern suggests that Bullfrog larvae can recognize cues of novel predators that may find them palatable, which could contribute to their success as an invasive species in the region.
Sex ratio, group composition, and male spacing were studied in Cordylus macropholis, a terrestrial lizard that inhabits the succulent Euphorbia caput-medusae. Repetitive sampling of two populations revealed highly female-biased sex ratios for adult, as well as juvenile size classes. The near 1:1 ratio observed in the smallest size class, however, suggests that the sex-ratio is 1:1 at birth. Sex ratio was found to relate positively to population density. Among aggregations containing more than one adult individual, a composition consisting of a male/female pair with or without juveniles, was the most common. Few cases were recorded where an adult male shared a plant shelter with more than one adult female or with another adult male. Adult males were randomly spaced among plants, both in and outside the mating season. Data on group structure and male spacing, especially the lack of clear differences between the mating and the nonmating season, provide little indication that male territoriality may be the cause of the highly female-biased sex ratio recorded for C. macropholis in the E. caput-medusae habitat.
The external stimuli that trigger ovulation and oviposition in anuran amphibians are poorly understood. We determined experimentally when during the mating process female Barking Treefrogs (Hyla gratiosa) become irrevocably committed to oviposition. We captured females at different points during the mating process, held them overnight without mates, and determined the following morning whether females had oviposited. Females arriving at the chorus and captured before entering amplexus did not oviposit, whereas 22% of females captured immediately after entering amplexus did. Ninety percent of females allowed to remain in amplexus for 1 h oviposited, and all females allowed to remain in amplexus for 1.5 h oviposited. Females that remained in amplexus for 1 h released significantly fewer eggs than did females that remained in amplexus for 1.5 h. These results indicate that amplexus, or a cue correlated with amplexus, triggers oviposition and that the number of eggs ovipositied increases with time spent in amplexus.
We conducted a field study to analyze spatial relationships among male Iberian Rock Lizards, Lacerta monticola. We then used the same individuals in a laboratory experiment to test whether avoidance responses of a male lizard in a previously unknown area is affected by presence of scents of familiar and unfamiliar resident males. Time spent attempting to escape in presence of unfamiliar odors was significantly higher than in presence of familiar odors suggesting avoidance of unfamiliar scent marks, which may lower the costs of aggressive interactions. Our results are concordant with previous studies in which differential tongue-flick rates showed discrimination between odors of familiar and unfamiliar males of L. monticola.
Uta stansburiana and Elgaria multicarinata occur on several California Channel Islands, and recent introduction of some populations has been suggested because of similarity in life-history traits and body size to mainland populations. We sequenced representatives of each species from mainland southern California and some of the islands on which they occur. For each species, cytochrome b sequence divergence is low across the narrow geographic area sampled. Analyses of 14 haplotypes of U. stansburiana suggest long-established residency on Santa Catalina and San Clemente Islands but more recent arrival on San Nicolas and Santa Cruz Islands. Analyses of eight haplotypes of E. multicarinata suggest these lizards may have been recently transported to San Nicolas Island.
Toe-clipping has been widely used for individual identification of amphibians and reptiles. It is costless and easy to apply and read. An animal's locomotor speed may affect its ability to acquire food, to avoid predation, and to achieve a high social status. Thus, it is of interest to determine whether toe-clipping affects the running speed of lizards. Wild caught Eastern Water Skinks (Eulamprus quoyii) were run in a race track in three consecutive sessions. In the first session, all animals were run with their toes intact. Half of the animals had their toes clipped between the first and second session, whereas the other half were toe-clipped between the second and the third session. Neither the average or maximum running speeds of lizards were affected by toe-clipping.
I raised tadpoles of the Common Frog (Rana temporaria) from populations in eight source ponds in southern Sweden, in a common garden experiment at two densities. Tadpoles from different populations differed in development rate; those from source ponds with high tadpole densities developed faster than those from less crowded ponds. Thus, differences among ponds in tadpole performance, which were documented in previous field studies, must have a genetic or maternal component. This result of source pond crowding likely resulted from microevolution and is an example of countergradient selection. In contrast, I found no significant effect of source pond hydroperiod; tadpoles from temporary ponds grew and developed at a rate similar to those from permanent ponds. Tadpoles of R. temporaria can respond plastically to pond drying by increasing development rate. I suggest adaptive plasticity in development rate decreased selection by pond drying in natural ponds.
We estimated survivorship, recapture probabilities and recovery rates in a threatened population of Flattened Musk Turtles (Sternotherus depressus) through a disease outbreak in Alabama in 1985. We evaluated a set of models for the demographic effects of disease by analyzing recaptures and recoveries simultaneously. Multiple-model inference suggested survival was temporally dynamic, whereas recapture probability was sex- and age-specifc. Biweekly survivorship declined from 98–99% before to 82–88% during the outbreak. Live recapture was twice as likely for male turtles relative to juveniles or females, whereas dead recoveries varied only slightly by sex and age. Our results suggest modest reduction in survival over a relatively short time period may severely affect population status.
The Spotted Salamander (Ambystoma maculatum) is widespread throughout the eastern United States and southern Canada. In 1997, we initiated a long-term study of A. maculatum at a breeding pond in Calhoun County, Alabama. Each winter, we captured salamanders as they returned to breed and inserted passive integrated transponders to permit positive identification of recaptures. We fit the von Bertalanffy growth-interval equation to data on snout–vent length taken from individuals captured and recaptured in different years and estimated intrinsic growth rates for both males and females. Males displayed rapid juvenile growth, which slowed as they neared estimated maximum size. Females, however, displayed relatively constant growth until nearing their estimated maximum size. The intrinsic growth rate of females was lower than that estimated for males. We hypothesize that sex-specific growth patterns maximize reproductive efforts of A. maculatum.
Lampropholis delicata is a small skink common in eastern Australia. The species is heliothermic and uses the ground litter layer. This study examined whether L. delicata showed preferences for particular structural features of the ground litter layer by observing their response to a number of pairwise choices of ground litter type. Lampropholis delicata showed a clear preference for a ground litter layer with an open structure. Difference in catch rates between pairwise comparisons was positively correlated with an index of habitat accessibility. It is suggested that this habitat preference is associated with the ability of the lizard to trade-off different activities. Selection of a habitat with some form of open structure may reduce the conflict between the need for foraging and basking, and the need to find shelter from predators.
Amphibians experience indeterminate growth, but although factors affecting larval growth are relatively well studied, less is known about correlates of postmetamorphic growth. We measured areas between lines of arrested growth (inter-LAG) to determine yearly growth rates to test whether the postmetamorphic growth of 32 Spotted Salamanders (Ambystoma maculatum) was related to age, sex, or year of emergence. Growth decreased with age and was not associated with sex or year of emergence. Using interLAG area as a metric of growth provides growth information in the years before first capture and can be done using the toe-clips commonly taken for marking individuals.
To determine the response of Mountain Yellow-Legged Frogs to short distance translocations, I placed transmitters on 20 adult frogs and moved them short distances from 144–630 m and monitored their responses for up to 30 days. Of the 20 translocated frogs, seven frogs returned to their original capture site, four frogs moved in the direction of their capture site but had not returned by the end of the study, and nine frogs did not return and were found at the translocation site. Apparently, displacing frogs was stressful, and translocated frogs lost body mass during the study period. Eighteen translocated frogs that were weighed at the beginning and end of the study lost body mass (mean loss was −1.2 g) compared to a group of 18 randomly selected PIT tagged frogs also weighed during the same tracking period (mean gain in body mass = 2.5 g) at our Kings Canyon study site. Translocation of adult Rana muscosa as a conservation tool may not be effective because some would simply attempt to return to their original capture site, and their homing may be stressful to an already declining frog population.