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Dispersal occurs when an individual leaves its natal area or home range, travels through adjacent areas, and then establishes a new home range where it will attempt to reproduce. Previous studies have suggested that subadults (i.e., hatchlings and juveniles) are the main agents of dispersal among introduced populations of Mediterranean Geckos, Hemidactylus turcicus. We derived a testable hypothesis for subadult dispersal in Mediterranean Geckos. In September 2006, we conducted tethering experiments to test the prediction that adults act aggressively toward subadults. From June to October 2006, we conducted 18 mark-recapture samples to test predictions of perch height occupancy and relative presence of adults and subadults at buildings and areas between buildings (i.e., transient habitats). As predicted, subadults occupied lower regions of buildings than adults, and subadults were disproportionately abundant in transient habitats. Apparently because of small sample size, there was no difference in the relative presence of adults and subadults at recently occupied buildings (i.e., arrival habitats). Our results supported the hypothesis that hatchlings were the main agents of diffusion dispersal within our study population and suggested that hatchling dispersal may be motivated by hostile encounters with adults. It was also clear that Mediterranean Geckos attempt to disperse from buildings more frequently than previously suggested.
We studied an Ambystoma maculatum (Spotted Salamander) population whose available terrestrial habitat varied in forest age, forest extent, and edge type to determine how microhabitats differed among habitats, whether A. maculatum displayed a nonrandom distribution of inbound capture locations, and whether individuals captured in different locations differed in age, body condition, and annual recapture rate. In this study, we use inbound capture location to infer direction of migration. Given this inference and the results of principle components analyses on surrounding habitat variables, we suggest that habitat differences in relation to litter depth, canopy cover, and soil water content best described the nonrandom distribution of A. maculatum captures. Differences in forest extent and edge type may also have contributed substantially to the A. maculatum migration capture pattern. Female salamanders arriving from the direction of the relatively mature, extensive forested habitat were significantly older than those arriving from the direction of the mature habitat with an agricultural edge, but there were no age differences among males. Body condition and annual recapture rates were similar among individuals regardless of capture location. Consistent with other work, we suggest that habitat protection efforts for A. maculatum, and similar species, should focus on extensive, forested habitat, with high levels of leaf litter and canopy cover and well-drained soils. Additionally, residential and agricultural edges may be more permeable than road edges for this species.
Recently, declines in amphibian populations all over the world have been reported. Global warming has the potential to become one of the most important causes for those declines, because reproductive activities of amphibians are affected severely by temperature and rainfall. It has been reported that climate warming has promoted a long-term tendency toward earlier breeding among amphibian populations in Europe and North America. However, some studies have not supported such a long-term change in the timing of amphibian breeding in those areas. We analyzed long-term data sets (12- to 31-year period) on the date of first spawning for four populations of three Japanese amphibians (Hynobius tokyoensis, Rana ornativentris, and Rhacophorus arboreus) in the suburbs of Tokyo and detected a significant trend toward earlier breeding in all populations examined. We also detected that the date of first spawning was correlated strongly with the mean monthly temperature just before the breeding season for each population examined. Given that the long-term trend of warming in the study district was significant, our investigation demonstrated that climate warming has affected the timing of breeding in at least some species or populations of amphibians in East Asia.
To test the hypothesis that male Korean salamanders, Hynobius leechii, respond to water vibrations via the mechanosensory lateral line system, we conducted a series of experiments. First, we examined behavioral responses of males to 0, 0.5, 1.0, and 1.5 Hz water vibrations generated by a model salamander, and we measured the number of times the males (1) oriented their heads toward the vibrating model; (2) approached within a 15-cm–diameter circle centered on the cloaca of the model; and (3) touched the model, as well as (4) the length of time the male stayed within the circle. To determine whether the mechanosensory lateral line system mediated these responses, we measured the same behavioral responses to 1.0 Hz water vibrations (1) both with and without a transparent vibration blocker placed between the model and test males, and (2) after exposing the test males to 0, 0.1, 0.5, and 1.0 mM concentrations of cobalt chloride for 1 h to disrupt the mechanosensory lateral line system. Test males showed significant responses to water vibrations from the model regardless of the vibration frequencies. Males showed significantly lower responses when a vibration blocker was placed and after cobalt chloride treatments. These results indicate that H. leechii males respond to water vibrations via the mechanosensory lateral line system. In addition, we describe aspects of the body undulation of mating males. This is the first clear result in urodeles that the mechanosensory lateral line system plays a role in male-male mating competition.
The Puerto Rican terrestrial frog (Eleutherodactylus coqui) has received considerable attention in Hawaii because of its rapid spread, loud mating calls, and its potential threat to native species. Thus far, its invasion potential on the Island of Hawaii remains poorly understood. Critical components for determining this potential are robust estimates of abundance and vital rates across habitat types. To address this lack of information, we used mark-recapture methods to estimate E. coqui survival and abundance, determine growth rates of adult male and female frogs, and relate densities to elevation, snout–vent length (SVL), habitat structure, and invertebrate abundance. Mean adult E. coqui density across eight sites was 62 ± 12 adults/100 m2 and ranged from 6–138 adults/100 m2. Our three-year mean adult density estimates were three times greater at three of our study sites (100 adults/100 m2) than the highest long-term estimates from Puerto Rico (33 adults/100 m2). Mean individual growth rates were 0.0078 mm/day (± 0.007 SD, N = 87) for males and 0.0097 mm/day (± 0.009 SD, N = 11) for females. Frogs of similar size were found to be growing slower in Hawaii than Puerto Rico. We found no relationship between elevation and E. coqui density or elevation and SVL or between invertebrate abundance and E. coqui density. However, there was a positive relationship between understory structure and E. coqui density. This relationship suggests that removing understory structure could reduce E. coqui densities, although other potential implications of this management treatment should be considered.
Herein I synonymize the ranid frog Platymantis rhipiphalcus, from New Britain, with Platymantis boulengeri, from the same island. The four mensural characters originally used to separate these frogs covary continuously with body size, and sex is highly correlated with body size, with females much larger than males. Consequently, no features other than size separate these presumptive species, and specimens described as P. rhipiphalcus merely represent males and juvenile females of P. boulengeri. Males of P. boulengeri are here recognized as such for the first time, which leads to the discovery that this species has the most extreme sexual size dimorphism yet reported for any anuran. Female body length averages >3 times that for males, and female body mass averages >40 times that for males. The physical mechanics of reproduction in a species exhibiting such extreme size dimorphism are unknown but will certainly merit future investigation.
This study is the first comprehensive systematic study on the python genus LeiopythonHubrecht 1879 native to New Guinea. The taxonomic arrangement recently made is critically reviewed, and proper descriptions for taxa herein recognized as valid are provided. Twenty external morphological characters were recorded from 90 preserved specimens from throughout most of the distribution of the genus. Thirteen characters were used with principal coordinate analysis to test the diversity of populations from different distributions. Additional evidence for some species was obtained by maximum parsimony and maximum likelihood analysis of mitochondrial DNA sequences (cytochrome b gene) taken from GenBank. Besides three conventional taxa, two new species from the mainland, and one new island species were recognized in accordance with the evolutionary species concept. Additionally, a new locality record is provided.
Extralimital populations of red-legged frogs have recently been found on Graham Island (Queen Charlotte Islands), British Columbia, and on Chichagof Island, Alaska. Both islands are well north of the traditionally understood (or core) range of red-legged frogs in western North America. The Chichagof Island frogs are known to be introduced, and the Graham Island frogs are suspected to be introduced. However, species-level identification of these populations remains uncertain. Recent phylogeographic analyses have demonstrated that there are two species of red-legged frogs, Rana aurora and Rana draytonii, and R. aurora is more closely related to the Cascades Frog, Rana cascadae (i.e., [auroradraytonii] is not monophyletic). Here, we compare new mtDNA sequence data from these extralimital populations to available sequences from 50 populations from the core range of red-legged frogs. These results demonstrate that both extralimital populations are the Northern Red-Legged Frog, R. aurora, and are most closely related to haplotypes found in the most northern clade of R. aurora. Further, we conduct ecological niche modeling under current conditions and future conditions that assume a global warming scenario to assess habitat suitability in southeastern Alaska and the Queen Charlotte Islands and the potential for the persistence and expansion of the extralimital populations. These analyses suggest that the extralimital populations occur in the most suitable habitat on Graham and Chichagof Islands and that suitability will increase on Graham and decrease on Chichagof Island in the future. These results are used to discuss several management options for the extralimital R. aurora.
Two lineages of Xantusia occurring in northwestern Mexico are each deeply divergent in mitochondrial and nuclear DNA, mutually exclusive relative to other members of the genus, and morphologically diagnosable. They are formally described here as new species. The new species from Sonora resembles its nearest relative, Xantusia arizonae, in that females lack well-developed femoral pores, but it differs in numbers of dorsal scales around midbody and in color pattern. It is found near the Sea of Cortez in a unique microhabitat, fallen Pachycereus pringlei (cardon), whereas X. arizonae occurs in rock crevices in central Arizona. The new species from Baja California Sur differs from its nearest relative, Xantusia gilberti, in color pattern and in having small scales bordering the labium behind the fifth infralabial. It is found in Yucca valida (datilillo) on the Magdalena Plains near the Pacific Coast, whereas X. gilberti occurs in pine-oak woodland of the Sierra La Laguna, 350 km to the south.
Clearcutting detrimentally affects the populations of many amphibian species. However, Gray Treefrogs (Hyla versicolor) have shown a preference for breeding sites located in clearcuts near forested habitat. To test the implications of this preference, we examined Gray Treefrog tadpole performance in cattle tanks along a gradient from clearcut to forest habitat. We replicated this design at three experimental clearcut sites. Tadpole performance was measured as length of the larval period, size at metamorphosis, and survival. We also examined the influence of temperature, periphyton productivity, and invertebrate predator abundances on tadpole performance. Time to metamorphosis was shorter in the clearcuts, but metamorphs tended to be smaller than metamorphs in the forest tanks. Survival was also greater in the clearcuts than in the forest treatments. Higher temperatures in the clearcuts primarily contributed to tadpole performance whereas invertebrate predators did not appear to influence performance. Although clearcuts benefited tadpoles through higher survival and shorter larval periods, there are potential fitness consequences for small metamorphs emerging in clearcuts.
Macrohabitat and microhabitat preferences of the endemic Fiji Tree Frog Platymantis vitiensis were investigated in Savura near Suva, Viti Levu, Fiji. Twelve sites in three habitat types (primary rain forest, disturbed secondary rain forest, and mahogany plantations) were surveyed from June 2004 to May 2005. The phenology of P. vitiensis was also studied along two permanent transects (adjacent to, and distant from, a stream bank) within the Savura area. Individuals were more abundant in primary rain forest than mahogany plantations and secondary rain forest. Individuals were common along stream banks, perched on riparian plants such as Pandanus, ferns, and Dolicholobium (and usually found 100–200 cm above the ground). Rainfall influenced activity, with fewer individuals observed during intense rainfall events. Adult frogs were more frequently encountered between July and October and gravid females between August and November. Hatchlings were more common during the dry season (May to October), whereas juvenile abundances peaked early in the wet season (November to April). Future surveying and monitoring of P. vitiensis populations should be conducted during March to July, when abundances are greater. The efficiency of rapid surveys can be maximized by subsampling along riparian vegetation, particularly where Pandanus are present.
We conducted a comparative study of the cephalic scales in xantusiid lizards. We describe the observed scutellation patterns, compare these to patterns observed in other squamates, and present a revised nomenclature for scincomorph cephalic scales that corrects some previous inconsistencies. Based on anatomical details and topographic relations in xantusiids and other scincomorphs, we suggest the following revisions. In xantusiids, we consider the paired scales previously called “frontals” to be “frontoparietals,” the single scale previously called the “median” to be the frontal, the paired scales previously called “nasals” to be “supranasals,” the paired scales previously called “postparietals” to be “occipitals,” and the single scale previously called the “occipital” to be the “interoccipital.” The paired scales previously called “pretemporals” in Cricosaura typica are considered “parietals,” whereas the pretemporals in Lepidophyma and most Xantusia are considered “supraoculars.” Based on these and other revisions, we propose primary homologies among scincomorph cephalic scales as a framework for future phylogenetic analyses, identify diagnostic characters for Xantusiidae and some of its subclades, and consider some costs of mistaken primary homology estimates to phylogenetic inference.
A new species of Atractus is described from Serra do Surucucu, a mountain slope at 1,000 m in the Guyana Shield, State of Roraima, Brazil. This species, only known by females, is diagnosed from all congeners by the following combination of characters: 17/17/17 smooth dorsal scale rows, without apical pits; 200–207 ventral scales; 25–26 subcaudal scales; moderate sized loreal, contacting second and third supralabials; seven supralabials, third and fourth contacting orbit; seven infralabials, first three contacting chinshields; moderate size, 222–388 mm SVL; short tail (7.7–8.8% snout–vent length); dorsal color pattern, in preservative, uniform chocolate to dark brown, with two conspicuous light paraventral lines, and a light incomplete occipital collar; venter immaculate creamish-white; tail uniform black; five maxillary teeth. We compared the new species with all currently recognized cis-Andean Atractus, and its affinities with Atractus alphonsehogei, Atractus caxiuana, Atractus collaris, Atractus gaigeae, Atractus limitaneus, and Atractus zidoki are discussed on the basis of putative morphological synapomorphies.
To improve our understanding of the distribution and abundance of amphibians and reptiles in tropical forests, herpetologists need to understand the relative effectiveness of different sampling techniques. However, current studies are biased by a focus on certain methods, species groups, or geographic regions. To address this problem, we conducted the first standardized comparison of patterns of species richness, rank-abundance, and community structure for both passive and active sampling methods for the study of herpetofauna in a tropical forest landscape. Moreover, we compare the effectiveness of these methods in primary and secondary forests and Eucalyptus plantation. Although different methods captured significantly different numbers of species and individuals, almost all techniques provided complementary benefits for the sampling of both lizards and leaf litter amphibians. The use of a limited set of methods can severely bias our understanding of changes in amphibian and lizard community structure in response to large-scale habitat change. Contrary to other studies, we recommend the use of pitfall traps in all studies, even Rapid Assessments (RAP), because they are indispensable for sampling many cryptic species, as well as being particularly cost effective for large-scale research. Because of the combination of complementary methods in sampling effectiveness, and the influence of method choice on taxon responses to habitat change, we recommend the use of multiple sampling techniques wherever possible. Synchronous adoption of multiple techniques in field studies will help improve sample representation and, thus, the understanding of species distributions and human impacts on herpetofauna in tropical forests.
We describe a new species of Ecnomiohyla from the vicinity of El Valle de Anton, Cocle, Panama. This is a large species that differs from similar species in the genus by details of the prepollex, webbing, and by the presence of a distinct expanded crista lateralis with medial proximal point. We provide descriptions of the adult and subadult, as well as the tadpole. We provide natural history information including observations of individuals gliding from the forest canopy, reproduction in tree holes, and male territoriality and care of the tadpoles. This species is currently known only from the immediate vicinity of El Valle de Anton, and we have observed numbers of this species in the wild to decrease dramatically following the recent epidemic of amphibian chytridiomycosis in the region.
Because they possess a highly unique long and projective tongue, chameleons have been viewed as strictly insectivorous and considered to use a specific tongue projection method in every feeding event. I report behavioral observations on fruit feeding by Furcifer oustaleti in the field as the first evidence of spontaneous feeding attempts on plant material by wild chameleons. Also, I present results of a feeding experiment to examine differences in feeding on fruits and insects. When chameleons fed on small fruits, most individuals directly picked up them with the mouth at short range, whereas chameleons almost always used tongue projection from a distance to capture small aerial insects. Such alternative feeding tactics occurred within individuals exposed to both foods over a short interval. These results suggest that chameleons discriminate food types to perform the appropriate feeding tactic to efficiently consume different types of food. When chameleons used the direct pickup tactic for fruit in the experiment, the tongue contacted the food item before the jaws did, suggesting that the chameleons have retained lingual prehension, the typical motor pattern of other iguanian lizards.
Ten Prairie Rattlesnakes (Crotalus viridis viridis) and 10 Western Diamondback Rattlesnakes (Crotalus atrox) were offered choices between envenomated (E) and nonenvenomated (NE) mice. Both species preferred E over NE mice when envenomation was accomplished by a conspecific but not when envenomation was accomplished by the other species. However, when envenomation was accomplished by Crotalus oreganus oreganus, E mice were preferred by C. v. viridis but not by C. atrox. Accordingly, we conclude that rattlesnakes of closely related species recognize each other's E prey, whereas rattlesnakes of distantly related species do not.
We studied the feeding behaviors of two sympatric species of caimans (Melanosuchus niger and Caiman crocodilus) during the dry season in the Mamirauá Sustainable Development Reserve, Amazonas State, Brazil. Observations were made in 50 × 13 m plots located along the land-water interface. We investigated the influence of interspecific density and the effects of temperature and water depth on the feeding behaviors of both species. We identified three principal categories of feeding behavior: trapping (with the body perpendicular to the shore, the caiman captures prey swimming close to the shore), active search (with the head under the water, the caiman searches for benthic prey), and jumping (leaping partially out of the water and capturing fish or other under water invertebrates prey). Using multiple linear regression, we found that water temperature had a negative effect on trapping by M. niger; and water depth did not affect feeding behaviors in either species. Density of M. niger did not affect either the density or the frequency of feeding by C. crocodilus. Results suggest that environmental factors have little influence on the feeding behaviors of the caimans we studied, and there is probably little interspecific competition for food during the dry season.