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At least 127 records · Page 7Linked to original sources
USGS1992

Descriptive risk assessment of the effects of acidic deposition on Rocky Mountain amphibians

We evaluated the risk of habitat acidification to the six species of amphibians that occur in the mountains of Colorado and Wyoming. Our evaluation included extrinsic environmental factors (habitat sensitivity and amount of acidic atmospheric deposition) and species-specific intrinsic factors (sensitivity to acid conditions, habitat preferences, and timing of breeding). Only one of 57 surveyed localities had both acid neutralizing capacity <200 μ eq/L and sulfate deposition >10 kg/ha/yr, extrinsic conditions with a possible risk of acidification. Amphibian breeding habitats in the Rocky Mountains do not appear to be sufficiently acidic to kill amphibian embryos. Some species breed in high-elevation vernal pools during snowmelt, and an acidic pulse during snowmelt may pose a risk to embryos of these species. However, the acidic pulse, if present, probably occurs before open water appears and before breeding begins. Although inherent variability of amphibian population size may make detection of declines from anthropogenic effects difficult, acidic deposition is unlikely to have caused the observed declines of Bufo boreas and Rana pipiens in Colorado and Wyoming. Amphibians in the Rocky Mountains are not likely to be at risk with acidification inputs at present levels.

Journal of Herpetology↗
USGS1993

Ecologically correlated morphological variation in tadpoles of the leopard frog, Rana chiricahuensis

Interspecific differences in tadpole morphology among leopard frogs of the Rana pipiens complex may represent adaptations to larval habitats. We documented variation in tadpole morphology among populations of R. chiricahuensis and compared intraspecific patterns of variation to those among species. Traits that exhibit similar patterns of variation in intraspecific and interspecific comparisons may represent adaptations to different larval habitats. Tadpoles of R. chiricahuensis found in streams have more contrasting melanic patterns on the tail, thicker dorsal fins, and somewhat larger tail muscles than those from ponds. Unexpected differences between tadpoles from two stream habitats might represent nonadaptive morphological variation. Alternatively, such differences may represent different morphological responses to similar selection pressures, to subtly different aquatic habitats (different selective regimes), or different developmental responses to different environmental cues. Parallels in variation for some morphological traits within and among tadpoles of leopard frog species support, but do not demonstrate, the contention that those morphological differences represent adaptations to larval habitats.

Journal of Herpetology↗
USGS1996

The proper name of the neotropical tree boa often referred to as Corallus enhydris (Serpentes: Boidae)

Confusion regarding the application of the proper scientific name for the common Neotropical tree boa has existed since Linnaeus described Boa enydris and Boa hortulana in 1758. We review the nomenclatural history of the species and point out the misapplication of scientific names that have characterized this form. Our review indicates that the proper scientific name for this highly variable, wide-ranging arboreal boid is Corallus hortulanus, not Corallus enydris, as has been used so frequently in recent years.

Journal of Herpetology↗
USGS1998

Size-sex variation in survival rates and abundance of pig frogs, Rana grylio, in northern Florida wetlands

During 1991-1993, we conducted capture-recapture studies on pig frogs, Rana grylio, in seven study locations in northcentral Florida. Resulting data were used to test hypotheses about variation in survival probability over different size-sex classes of pig frogs. We developed multistate capture-recapture models for the resulting data and used them to estimate survival rates and frog abundance. Tests provided strong evidence of survival differences among size-sex classes, with adult females showing the highest survival probabilities. Adult males and juvenile frogs had lower survival rates that were similar to each other. Adult females were more abundant than adult males in most locations at most sampling occasions. We recommended probabilistic capture-recapture models in general, and multistate models in particular, for robust estimation of demographic parameters in amphibian populations.

Journal of Herpetology↗
USGS1999

Genetic and morphometric assessment of an unusual tortoise (Gopherus agassizii) population in the Black Mountains of Arizona

Under recent regulatory designation of the U.S. Fish and Wildlife Service, desert tortoises (Gopherus agassizii) occurring east and south of the Colorado River constitute the Sonoran population, whereas those to the west and north form the Mojave population. These management units, distinguished by significant genetic, morphometric, and ecological differences, represent deep phylogenetic subdivisions within G. agassizii and are of high conservation value. We provide genetic and morphological profiles for an unusual tortoise population inhabiting the Black Mountains of Arizona, some 40 km east of the Colorado River. Both mitochondrial (mt) DNA and morphometric analyses revealed predominately Mojavean features: ten of eleven Black Mountain tortoises possessed Mojave mtDNA markers, and 24 of 37 animals exhibited Mojave morphometric phenotypes. Our results indicate west-to-east movement of tortoises across the Colorado River, though how or when a Mojave lineage became established in the Black Mountains is difficult to ascertain. Active dispersal, river meander, and human transport (early or modern peoples) serve as plausible explanations. Future management of the Black Mountain tortoises should emphasize the population's Mojavean affinities.

Journal of Herpetology↗
USGS1997

Female reproductive dynamics in a Maryland population of ringneck snakes (Diadophis punctatus)

Adult female ringneck snakes (Diadophis punctatus) collected from a Maryland population during five successive summers laid a total of 50 clutches in which all eggs hatched successfully under laboratory conditions. Mean hatchling mass was not significantly related to female mass or clutch size when each was evaluated in separate analyses, but was significantly related to these factors when they were evaluated in a joint analysis. Mean hatchling masses of 0.6-1 g appear most adaptive; when females are large enough to produce 1-g eggs, the tendency is to produce a larger number of relatively smaller eggs. The relationship of clutch mass to female mass was unaffected by clutch size. Reproductive effort, measured as relative clutch mass (RCM, clutch mass/female mass), increased with age, as indicated by snout-vent length (SVL); also, the relationship of clutch mass to female mass indicated that clutches equaled a larger percentage as female mass increased. Clutch size averaged 3.55 eggs and ranged from 2 to 6. Clutches were laid from 17 June through 21 July (35 d), median 2 July. Clutches hatched during the 20-d interval 8-27 August (median August 18). Larger clutches were laid earlier in the season on average than smaller clutches. Incubation periods for clutches averaged 47 (range 42-51) d. Clutches laid later in the season averaged shorter incubation periods than clutches laid earlier.

Journal of Herpetology↗
USGS2001

Diagnostic histological findings in Yosemite toads (Bufo canorus) from die-off in the 1970s

Twelve adult and 25 larval Yosemite toad ( Bufo canorus ) specimens from the eastern Sierra Nevada of California were examined histologically for evidence of infectious, toxicological, and degenerative diseases. The preserved toads were selected from 21 that had been salvaged or collected during a die-off in 1976-1979 that immediately preceded a population decline. Causes of death of four toads were determined histologically; clinical signs and field observations suggested causes of death of three more. Four toads died of infectious diseases, including chytridiomycosis of the skin ( N = 1), bacillary septicemia ( N = 2), and combined chytridiomycosis and bacterial septicemia ( N = 1). Infections by a funguslike organism ( Dermosporidium penneri ), renal myxozoa ( Leptotheca ohlmacheri ), larval Rhabdias, various gastrointestinal nematodes, urinary bladder flukes, and lung flukes were detected in five specimens. No evidence of degenerative diseases, virus infections, or intoxications was found. The variety of lethal diseases and our inability to determine the causes of death of five specimens suggests that one or more histologically undetectable diseases or intoxications may have also contributed to the deaths and population decline.

California↗
USGS2010

Oviduct modifications in foam-nesting frogs, with emphasis on the genus Leptodactylus (Amphibia, Leptodactylidae)

Various species of frogs produce foam nests that hold their eggs during development. We examined the external morphology and histology of structures associated with foam nest production in frogs of the genus Leptodactylus and a few other taxa. We found that the posterior convolutions of the oviducts in all mature female foam-nesting frogs that we examined were enlarged and compressed into globular structures. This organ-like portion of the oviduct has been called a “foam gland” and these structures almost certainly produce the secretion that is beaten by rhythmic limb movements into foam that forms the nest. However, the label “foam gland” is a misnomer because the structures are simply enlarged and tightly folded regions of the pars convoluta of the oviduct, rather than a separate structure; we suggest the name pars convoluta dilata (PCD) for this feature. Although all the foam-nesters we examined had a pars convoluta dilata , its size and shape showed considerable interspecific variation. Some of this variation likely reflects differences in the breeding behaviors among species and in the size, type, and placement of their foam nests. Other variation, particularly in size, may be associated with the physiological periodicity and reproductive state of the female, her age, and/or the number of times she has laid eggs.

South American Journal of Herpetology↗