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Barking Frogs (Eleutherodactylus augusti) are the northernmost ranging member of the large tropical family Leptodactylidae. We investigated the ecology of this saxicolous species at the northern edge of its range in a canyon in southern Arizona. We captured 54 frogs on discontinuous rock outcrops; eight of nine females and 39 of 45 males were on limestone outcrops. The remaining frogs were closer to limestone outcrops by more than 200 m than would be expected if they were distributed randomly with respect to limestone formations. Seven of 10 frogs radio-tracked had core home ranges (50% fixed kernel) from 94 to 100% on limestone; the other three frogs did not have any part of their home range on limestone outcrops. During five years of mark-recapture efforts, no frogs were found on a different outcrop from the one where they were originally captured; no radio-tracked frogs moved between outcrops during the breeding season. We estimated that four to 20 Barking Frogs occupied each outcrop; these groups probably are connected primarily by juvenile dispersal. As an organism living at the edge of its range, Barking Frogs in Arizona may rely heavily on extensive underground areas such as those found in limestone to protect them from a physiologically challenging environment. To manage for the persistence of Barking Frogs in southern Arizona, we must identify and protect habitat patches and movement pathways among them.
We used mitochondrial DNA sequences to investigate the phylogenetic relationship of Rana subaquavocalis and Rana chiricahuensis. We sequenced 1344 base pairs of the mitochondrial control region from 39 samples of R. subaquavocalis and 53 samples of R. chiricahuensis from localities throughout their Arizona range. In maximum-likelihood analysis, R. subaquavocalis samples were on a short branch within the southern Arizona clade of R. chiricahuensis. We also found two distinct lineages of R. chiricahuensis, one on the Mogollon Rim of central Arizona and one in southern Arizona. Our results are consistent with the hypothesis that R. chiricahuensis and R. subaquavocalis are conspecific.
A new genus and species of lizard is described from far northern New Caledonia and the Îles Belep, to the north of the New Caledonian mainland. In overall appearance and biology, it is most similar to the forest-dwelling species of the endemic New Caledonian genus Marmorosphax and shares with those skinks a live-bearing mode of reproduction. However, the new species is highly divergent in its scalation and includes a combination of character states not seen in any other New Caledonian species. The new species has been recorded mainly from dry forest habitats in the far north of the region, including dry closed forest on the Îles Belep, dry riverine forest adjacent to the Rivière Néhoué, and dry closed forest on Dome de Tiébaghi. The forests in which this new species is found are now present as relictual patches as a result of historical factors or more recent anthropogenic impacts. The taxonomic uniqueness of this species, in combination with its restricted distribution and threats to its preferred habitat, make it a high priority for conservation management.
An interesting case of reproductive specialization among anurans is found in bromeligen species that have reproductive cycles associated with bromeliads. In these species, male reproductive activity might be related not only to macroclimatic patterns but also to the availability of suitable microhabitats in bromeliads. This research focuses on one bromeligen species from Southeastern Brazil, Scinax perpusillus, that is territorial and uses bromeliads as retreat and oviposition sites. Two populations were studied (Intervales State Park and Boracéia Biological Station, both in the state of São Paulo, Brazil). Available bromeliads vary substantially in morphology and position in the forest. Thus, we examined whether male frogs (1) select plants with specific eco-morphological traits, (2) call at specific time periods within the reproductive season, and (3) call more actively under certain temperature and humidity conditions. Patterns of male calling activity within the reproductive season varied between years and between populations, but calling was not more intense during warmer or more humid periods. It seems, then, that subtle patterns of phenology might vary significantly between populations and across years. Bromeliad choice was nonrandom. Males chose bromeliads that were larger, clustered, closer to the ground, and had higher reservoir pH, features that probably reflect the quality of the plants as oviposition sites and that might confer social advantages by reducing conflict with neighboring males.
The coloration of animal integuments evolves in response to numerous and often competing selective pressures. Although male-male competition and female mate choice characteristically select for increased color conspicuousness, visibility to predators and to prey often select for decreased conspicuousness. We examined three populations of Common Collared Lizards, Crotaphytus collaris, in Oklahoma (Arcadia Lake, Glass Mountains, Wichita Mountains) that have been argued to differ in the intensity of natural and sexual selection acting on their color patterns. Our study had two main objectives. First, reflectance spectra were obtained from the lizards to replicate and extend previous work on differences in sexual dichromatism among these populations. Second, spectra were gathered on components of visual backgrounds at our study sites to explore the possibility that each population may be relatively cryptic within its own habitat. Results showed that most body regions differed significantly in sexual dichromatism among populations, but in contrast to prior work, no one population was more sexually dichromatic than another for all body regions examined. Males exhibited less overlap in coloration with their visual backgrounds than did females (i.e., males were more conspicuous), and females overlapped more in coloration with rocks than with other visual backgrounds. The population estimated previously to experience the strongest predation pressure (Arcadia Lake) was shown in the present study to be the least conspicuous. Some support also was found for the proposition that even the most “colorful” population (Wichita Mountains) may not always be conspicuous when viewed against its typical visual background.
The North American Amphibian Monitoring Program uses a ranked, categorical calling index to estimate anuran abundance. However, there are few data assessing the assumption that calling index values are accurate indicators of population sizes or to suggest ranges of population sizes associated with specific values of the calling index. This study compared mark-recapture population estimates and call rates to calling index values for Green Frogs (Rana clamitans) in the Upper Peninsula of Michigan. Mean mark-recapture population size estimates and mean calls per minute were greater in ponds with larger calling index values. Similarly, calls per minute increased with increasing population size, although rate of increase declined at high population sizes possibly caused by a higher proportion of noncalling satellite males at high densities. Sex ratios in breeding habitat along the edges of ponds were increasingly male biased as population size increased. These data support the assumption that calling index values are useful indicators of abundance of R. clamitans.
Chelydrids (including snapping and big-headed turtles) are unusual among extant turtles in possessing long, robust tails. In other lineages of quadrupedal reptiles, long tails perform critical functions during both terrestrial and aquatic locomotion, and the tails of Common Snapping Turtles have been shown to help stabilize juveniles as they ascend terrestrial slopes. However, Common Snapping Turtles live primarily in aquatic habitats, and the function of the tail in these environments has not been examined. The first step to evaluating the role of the chelydrid tail in water is to evaluate its pattern of motion; therefore, we collected high-speed digital video of tail kinematics from juvenile Common Snapping Turtles (Chelydra serpentina) during aquatic walking. Common Snapping Turtles hold the tail off the substrate and move it as a nearly rigid strut during aquatic walking, cyclically flexing it side to side by 11–12° from the body midline. These motions occur one-quarter cycle out of phase with the motions of the limbs; thus, the timing of tail movements suggests that they are likely not a passive consequence of hind-limb retraction and are likely controlled by one (or a combination) of tail muscles, rather than ipsilateral hind-limb retractors. The potential for tail movements to contribute to aquatic thrust in Common Snapping Turtles is uncertain. However, Common Snapping Turtle tail movements resemble those of salamanders and lizards in many respects, suggesting that Common Snapping Turtles might retain primitive tetrapod or sauropsid features of tail motor control despite possessing a radically divergent body plan.
Despite concern over amphibian declines, few studies estimate absolute abundances because of logistic and economic constraints and previously poor estimator performance. Two estimation approaches recommended for amphibian studies are mark-recapture and depletion (or removal) sampling. We compared abundance estimation via various mark-recapture and depletion methods, using data from a three-year study of terrestrial salamanders in Great Smoky Mountains National Park. Our results indicate that short-term closed-population, robust design, and depletion methods estimate surface population of salamanders (i.e., those near the surface and available for capture during a given sampling occasion). In longer duration studies, temporary emigration violates assumptions of both open- and closed-population mark-recapture estimation models. However, if the temporary emigration is completely random, these models should yield unbiased estimates of the total population (superpopulation) of salamanders in the sampled area. We recommend using Pollock's robust design in mark-recapture studies because of its flexibility to incorporate variation in capture probabilities and to estimate temporary emigration probabilities.
We examined cytogenetic features and reproductive capacity in newly arisen tetraploid amphibians. Autotetraploids were produced by suppressing second polar body formation in haploid eggs of diploid females of Rana nigromaculata inseminated with diploid sperm of autotetraploid R. nigromaculata. Allotetraploids were also produced by suppressing second polar body formation in haploid eggs of diploid females of Rana porosa brevipoda inseminated with diploid sperm of autotetraploid R. nigromaculata. In male R. nigromaculata autotetraploid offspring, mostly quadri- and bivalents were found in Metaphase I, and 26 dyads were seen in Metaphase II. Autotetraploid males were then mated with autotetraploid females, and most of the resultant offspring were tetraploids possessing four chromosome sets of diploid R. nigromaculata. Male allotetraploid offspring showed 26 bivalents in Metaphase I and 26 dyads in Metaphase II. A large number of the offspring resulting from crosses between allotetraploid males and females were tetraploids having chromosome sets of diploid R. nigromaculata and diploid R. p. brevipoda. These results seem to indicate that, if such tetraploids develop a distinguishing premating mechanism, they should continue as a sexual fertile species in one generation and coexist with their diploid parental species.
A new species of bufonid toad in the genus Melanophryniscus, from the province of Misiones, northeastern Argentina, is described. It is included in the stelzneri group and is most similar to Melanophryniscus atroluteus than to any other species. Melanophryniscus sp. nov. is distinguished, by having a uniformly brown dorsal coloration, numerous white spots along the mandibular arch; the pupil surrounded by a golden ring; the iris gold, finely spotted with dark brown; and the frontoparietal fontanelle widely exposed anteriorly. Moreover, the advertisement call of the new species is noticeable longer than the call of M. atroluteus and has a higher dominant frequency. The Melanophryniscus species present in Misiones are discussed and several areas of syntopy are reported.
Call surveys are a relatively new and efficient technique for detecting the presence of breeding male anurans. Using data from multiple surveys of breeding choruses of Wood Frogs (Rana sylvatica) combined with counts of egg masses on ponds in west-central Alberta we determined (1) the relationship between ranks of chorus size and total number of egg masses in ponds, and (2) number of breeding males in standard chorus-size ranks (1, 2 and 3). Estimates for Rank 3 choruses were based on a formula with number of egg masses present per pond and a fixed male to female ratio of 2:1 calculated from the literature. Calling males were recorded from all ponds that had evidence of female reproductive activity (i.e., egg masses). Generalized linear models suggested that ranks were positively and linearly correlated with the number of egg masses in a pond. In addition, call data from only the second of four sampling periods (each 3–6 days) significantly predicted number of egg masses in ponds, suggesting that timing is important when surveying calling wood frogs. The mean number of chorusing males per rank did not correspond to aural ranks of calling intensity: Rank 1 = 1.3 males, Rank 2 = 3.7 males, and Rank 3 = 118 males. We recommend similar assessments for other widely distributed species to improve our ability to detect and interpret habitat-use patterns and population trends of amphibians through monitoring programs.
Previous molecular work on salamanders of the genus Bolitoglossa recognized the “Magnadigita” clade, which includes members of the Bolitoglossa dunni, Bolitoglossa franklini, and Bolitoglossa rostrata species groups. One well-supported clade within the B. dunni group includes Bolitoglossa celaque, Bolitoglossa synoria, and an undescribed taxon from El Salvador and Guatemala. I describe the last taxon as a new species based on published molecular evidence and morphological differences among closely related congeners. The new species is readily distinguished from B. celaque by dorsal coloration and from B. synoria by foot morphology.
When rapid changes in environmental factors occur in tropical rain forests, anurans may behaviorally alter their vertical microhabitat in response. Friajes are extreme weather phenomena that bring cold southern winds into Amazonia. Five friaje events during 1997 and 1998 in southern Peru were studied to examine whether anuran populations differed between visual encounter surveys conducted on friaje nights versus non-friaje nights. Anuran diversity, species richness, and number of hylid individuals were significantly greater during friajes in Peru. Friajes alter anuran vertical distributions by causing arboreal frogs to descend to lower levels in order to avoid the cold temperatures and desiccating winds associated with friajes.
The scincid genus Tropidophorus is diagnosed by a suite of derived morphological characters, one of which is newly recognized: the corners of the eyelid form within one scale instead of between two. This character occurs elsewhere only in the distantly related Cophoscincopus and may be related to semiaquatic habits of both taxa. For Tropidophorus, we also report a novel arrangement of supraciliary scales in some species, which is potentially useful in inferring intrageneric relationships; a deeply bifurcated hemipenis, confirming the taxon as a member of the Sphenomorphus group of lygosomine skinks; further details of the taxonomic and sexual occurrence of postanal pores in the genus, and the presence of a pale iris, which contrasts with the dark iris of most other members of the Sphenomorphus group. We also note patterns of endemism in the genus and an unusual disjunction in the distribution.
The taxonomic status of Bufo simusSchmidt, 1857, is reviewed. Comparisons of the lectotype with members of different species groups of South American Bufo, reveal that B. simus is a junior synonym of Bufo spinulosus Wiegmann.
Eurycea cirrigera, a relatively small species that occurs in the Allegheny Mountains, appears to fill in the gaps along the aquatic-terrestrial gradient that are left by two sympatric salamander species; the terrestrial Plethodon cinereus and semiaquatic Desmognathus fuscus. To better understand the local distribution of these three species we tested the hypothesis that E. cirrigera is better able to utilize a variety of microhabitats than P. cinereus or D. fuscus. In field enclosures change in mass in relation to initial mass, as a proxy of fitness, was compared for each species, in three different habitats (stream, stream bank, and forest) over time. Independent of species the stream habitat showed a significant negative effect on the fitness of all individuals. Additionally, E. cirrigera showed significantly higher fitness than P. cinereus over all three treatments. The mean fitness of D. fuscus was intermediate, but not significantly different than P. cinereus or E. cirrigera. These results suggest that, in the absence of predation and competition, E. cirrigera is not negatively affected by being a generalist.
Several species of lizards exhibit significant annual variation in reproductive traits; however, most work in this area focused on populations from temperate latitudes or low to medium elevations. We examined annual variation in litter size, neonate size, and relative litter mass in a high elevation (4200 m) population of the viviparous lizard, Sceloporus bicanthalis from the Volcano Nevado de Toluca, México. We found little evidence for annual variation in reproduction in this population. Female body size influenced litter size and litter mass. Relative litter mass in this population (0.47) was among the highest reported for any Sceloporus and may be a consequence of a nearly “annual” life cycle. Mean neonate size was not affected by female SVL or litter size, suggesting it may be optimized in this population.
Behavior of young tortoises released from seminatural nurseries could be affected by the length of time spent within the nursery before release. We tested whether neonate (under two months) and juvenile (8–9 years) Desert Tortoises selected hibernation burrows with differing characteristics after release from their natal pen. Burrow habitat (canopy cover and landscape slope) did not differ between age classes. Juvenile tortoises were larger than neonates and, therefore, used larger burrows than neonates, but their burrows were a closer fit to tortoise size than were the neonate burrows. Juvenile burrow orientation differed significantly from a uniform distribution, with a mean direction of 162° (SSE); the burrows of neonates were not oriented in any particular direction. Selectivity of juveniles compared to neonates may have contributed to higher levels of movement by juveniles between release and hibernation. These age-related differences in behavior should be incorporated into nursery-based management plans.
Many lizards are known to alter their thermal ecology during pregnancy, although body temperatures oF pregnant/gravid females may either increase or decrease, depending on the species. Most of the data available on this phenomenon come from temperate taxa. In the present study, we compared field body temperatures (Tb) of pregnant females with those of nonpregnant females and males of three species of viviparous skinks (Mabuya agilis, Mabuya macrorhyncha, and Mabuya frenata) from southeastern Brazil. We found that pregnant females did not differ in Tb from nonpregnant animals (including males). Thus, reproductive condition did not influence body temperatures regulation by these skinks to a significant degree.
The Smooth Snake, Coronella austriaca, is an ambush predator that waits for its main prey, the Wall Lizard, Podarcis muralis, inside dark rock crevices where lizards retreat. Pheromonal secretions of lizards could be used by snakes to select foraging sites but also during predatory episodes when identifying lizards under conditions of low visibility is beneficial. We used cotton applicators labeled with lizard scent to determine whether Smooth Snakes can discriminate the chemical cues of Wall Lizards. We also asked whether snakes could discriminate between male and female lizards, or detect male scents before female ones, which could indicate differential susceptibility of the sexes to predation. The greater tongue-flick rate in response to Wall Lizard scent than to deionized water or cologne indicated that C. austriaca is able to discriminate the chemical cues of Wall Lizards, but it did not discriminate between the sexes of lizard prey.
The diet of two rice-field inhabiting snakes, Elaphe quadrivirgata and Rhabdophis tigrinus, was examined with reference to rice-field anuran fauna. Although adult Hyla japonica and Rhacophorus schlegelii inhabit rice fields temporarily in spring for reproduction, juvenile Rana nigromaculata and Rana limnocharis are residents of rice fields after emerging in early summer. In response to these seasonal changes, both snakes shifted their prey selection dramatically from adults of H. japonica and Rh. schlegelii in spring to juveniles of Ra. nigromaculata and Ra. limnocharis in summer. These results strongly suggest that the seasonal partitioning of rice-field habitats between small adult frogs and juveniles of larger frogs allows these snakes to continuously forage in rice fields throughout the warm season.
The Swamp Skink, Egernia coventryi, is an uncommon species that inhabits wetlands and swampy heaths in predominantly coastal regions of southeastern Australia. We examined museum specimens to quantify the diet, reproduction, and sexual dimorphism of E. coventryi. The mean SVL of both adult males and females was 85–86 mm, and individuals attain sexual maturity at about 72–74 mm SVL. Although the sexes did not differ in body size (SVL), males have longer and broader heads than females, both in terms of absolute head size and head size relative to body size. Females ovulate in September and October with parturition occurring in late January or early February. However, not all adult females collected during the breeding season were pregnant, suggesting that female E. coventryi may not always breed annually. Litter size in E. coventryi ranged from 1–4, with a mean litter size of 2.6. Egernia coventryi is omnivorous and a largely opportunistic forager, with spiders (found in 16 of 47 individuals, 34%), beetles (26%), lepidopterans (17%), ants (11%), hemipterans (9%) and aquatic amphipods (9%) the most common animal prey items found in the alimentary canals of individuals. However, plant materials (e.g., fruits/berries, seeds, other vegetation) also were found in the stomachs of the majority of the specimens (66%). Sloughed skin (26%) and the tail fragment of another E. coventryi were found in the alimentary tracts of preserved specimens. The majority of specimens (76%) were infested with endoparasites, with one specimen containing 130 nematodes, although the mean number of nematodes per specimen was 8.87.
The Norway Rat (Rattus norvegicus) was a major predator on hatchling and juvenile Diamondback Terrapins (Malaclemys terrapin) in a New York population during three years (2001–2003). Rats killed young terrapins by evisceration through the plastron or carapace, exclusively at night, and during two distinct periods: (1) at emergence from nests in August and September; and (2) at emergence from hibernation in April. Predation rates were highest during peak emergence from nests and hibernacula. In the fall, hatchlings were mainly preyed upon within intertidal high marsh vegetation, where hatchlings normally occur after emergence from nests. We found no evidence of rat predation on eggs or hatchlings in nests. Predation in the spring also occurred in the intertidal high marsh, but rats killed juveniles in adjacent terrestrial habitats as well. We used data from a telemetry study of 24 wild hatchlings to estimate rat predation rates. Between 13 September and 22 October 2003, 16 of 24 (67%) radio-tracked hatchlings were killed by rats.