Trace Amounts of Ranavirus Detected in Common Musk Turtles (Sternotherus odoratus) at a Site Where the Pathogen Was Previously Common.

Ranaviruses are global multi-host pathogens that infect ectothermic vertebrates and cause mass mortality events in some species. In 2021-2022, we surveyed two species of aquatic turtles in a Virginia site where previous research found ranavirus in lizards (Sceloporus undulatus) and turtles (Chrysemys picta picta and Terrapene carolina carolina). We sampled tissues from 206 turtles and tested 249 samples (including recaptures) for ranavirus using qPCR. We detected trace amounts of ranavirus DNA in 2.8% of Common Musk Turtles (Sternotherus odoratus). We did not detect the virus in Eastern Painted Turtles (C. p. picta). The Ct values from animals carrying ranavirus corresponded to positive controls with a concentration of one copy of ranavirus DNA per microliter and likely reflect DNA in the environment rather than ranavirus infection in turtles. Turtles carrying ranavirus DNA came from only one pond in one year. The amount of ranavirus in our study site, as indicated by tissue samples from turtles, appears to have dropped dramatically since previous research conducted over a decade ago. This study represents the first report of ranavirus detected in S. odoratus and contributes to the scarce literature on longitudinal surveys of ranavirus in wild chelonians. We emphasize the need for large sample sizes and multi-year sampling to detect this pathogen in wild populations.

Influence of Herbicide Exposure and Ranavirus Infection on Growth and Survival of Juvenile Red-Eared Slider Turtles (Trachemys scripta elegans).

Ranaviruses are an important wildlife pathogen of fish, amphibians, and reptiles. Previous studies have shown that susceptibility and severity of infection can vary with age, host species, virus strain, temperature, population density, and presence of environmental stressors. Experiments are limited with respect to interactions between this pathogen and environmental stressors in reptiles. In this study, we exposed hatchling red-eared slider turtles (Trachemys scripta elegans) to herbicide and ranavirus treatments to examine direct effects and interactions on growth, morbidity, and mortality. Turtles were assigned to one of three herbicide treatments or a control group. Turtles were exposed to atrazine, Roundup ProMax®, or Rodeo® via water bath during the first 3 weeks of the experiment. After 1 week, turtles were exposed to either a control (cell culture medium) or ranavirus-infected cell lysate via injection into the pectoral muscles. Necropsies were performed upon death or upon euthanasia after 5 weeks. Tissues were collected for histopathology and detection of ranavirus DNA via quantitative PCR. Only 57.5% of turtles exposed to ranavirus tested positive for ranaviral DNA at the time of death. Turtles exposed to ranavirus died sooner and lost more mass and carapace length, but not plastron length, than did controls. Exposure to environmentally relevant concentrations of herbicides did not impact infection rate, morbidity, or mortality of hatchling turtles due to ranavirus exposure. We also found no direct effects of herbicide or interactions with ranavirus exposure on growth or survival time. Results of this study should be interpreted in the context of the modest ranavirus infection rate achieved, the general lack of growth, and the unplanned presence of an additional pathogen in our study.

Survey of Ranavirus and Batrachochytrium dendrobatidis in Introduced Frogs in Hawaii, USA.

Ranaviruses and the fungus Batrachochytrium dendrobatidis are globally important agents of emerging infectious amphibian diseases. Amphibians on Oahu, the Hawaiian Island with the greatest potential for disease introduction through the movement of goods and people, have never been surveyed for ranaviruses or B. dendrobatidis. We surveyed all five species of frogs on Oahu, Hawaii, US for these pathogens. Of 325 individuals sampled from six sites, none were positive for ranavirus. However, we found B. dendrobatidis in a total of four individuals of three species, the cane toad (Bufo marinus), the American bullfrog (Rana catesbeiana), and the greenhouse frog (Eleutherodactylus planirostris), but not in the green and black poison dart frog (Dendrobates auratus) or the Japanese wrinkled frog (Rana rugosa). The apparent lack of ranavirus and low prevalence of B. dendrobatidis are noteworthy given how widespread these pathogens are in terms of both global distribution and host range. Surveillance should continue to document any changes in B. dendrobatidis prevalence or the arrival of ranaviruses in Hawaii.

Influence of geography and climate on patterns of cell size and body size in the lizard Anolis carolinensis.

Geographic patterns in body size are often associated with latitude, elevation, or environmental and climatic variables. This study investigated patterns of body size and cell size of the green anole lizard, Anolis carolinensis, and potential associations with geography or climatic variables. Lizards were sampled from 19 populations across the native range, and body size, red blood cell size and size and number of muscle cells were measured. Climatic data from local weather stations and latitude and longitude were entered into model selection with Akaike's information criterion to explain patterns in cell and body sizes. Climatic variables did not drive any major patterns in cell size or body size; rather, latitude and longitude were the best predictors of cell and body size. In general, smaller body and cell sizes in Florida anoles drove geographic patterns in A. carolinensis. Small size in Florida may be attributable to the geological history of the peninsular state or the unique ecological factors in this area, including a recently introduced congener. In contrast to previous studies, we found that A. carolinensis does not follow Bergmann's rule when the influence of Florida is excluded. Rather, the opposite pattern of larger lizards in southern populations is evident in the absence of Florida populations, and mirrors the general pattern in squamates. Muscle cell size was negatively related to latitude and red blood cell size showed no latitudinal trend outside of Florida. Different patterns in the sizes of the 2 cell types confirm the importance of examining multiple cell types when studying geographic variation in cell size.

Out of Florida: mtDNA reveals patterns of migration and Pleistocene range expansion of the Green Anole lizard (Anolis carolinensis).

Anolis carolinensis is an emerging model species and the sole member of its genus native to the United States. Considerable morphological and physiological variation has been described in the species, and the recent sequencing of its genome makes it an attractive system for studies of genome variation. To inform future studies of molecular and phenotypic variation within A. carolinensis, a rigorous account of intraspecific population structure and relatedness is needed. Here, we present the most extensive phylogeographic study of this species to date. Phylogenetic analyses of mitochondrial DNA sequence data support the previous hypothesis of a western Cuban origin of the species. We found five well-supported, geographically distinct mitochondrial haplotype clades throughout the southeastern United States. Most Florida populations fall into one of three divergent clades, whereas the vast majority of populations outside Florida belong to a single, shallowly diverged clade. Genetic boundaries do not correspond to major rivers, but may reflect effects of Pleistocene glaciation events and the Appalachian Mountains on migration and expansion of the species. Phylogeographic signal should be examined using nuclear loci to complement these findings.

Temperature-induced plasticity at cellular and organismal levels in the lizard Anolis carolinensis.

Among ectotherms, individuals raised in cooler temperatures often have larger body size and/or larger cell size. The current study tested whether geographic variation in cell size and plasticity for cell size exist in a terrestrial, ectothermic vertebrate, Anolis carolinensis Voigt, 1832. We demonstrated temperature-induced plasticity in erythrocytes and epithelial cells of hatchlings lizards derived from the eggs of females sampled from four populations and incubated at multiple temperatures. Larger cells were produced in hatchlings from cooler treatments; however, hatchling body size was unaffected by temperature. Therefore, temperature-induced plasticity applies at the cellular, but not organismal, level in A. carolinensis. In addition, reaction norms for cell size differed among populations. There was a latitudinal trend in cell size and in plasticity of cell size among our study populations. The two southernmost populations showed plasticity in cell size, whereas the two northernmost ones did not. We suggest that selection pressure for larger cell size in northern, cooler environments has restricted plasticity in A. carolinensis applied at the cellular level in response to variable incubation environments.

Latent effects of egg incubation temperature on growth in the lizard Anolis carolinensis.

Varied egg incubation temperatures can result in immediate effects on the phenotype of reptiles, and also latent effects that can augment or contradict effects evident at egg hatching. I examined the effects of incubation temperature on embryonic development, hatching morphology, and subsequent growth in multiple populations of the lizard Anolis carolinensis. Eggs from wild-caught females in four populations were incubated at up to three temperatures, 23.5, 27, and 30 degrees C. Measures of body size were collected immediately after hatching and weekly thereafter, while juveniles were maintained in a common laboratory environment for 8 weeks. Cooler incubation temperatures resulted in longer incubation periods but did not affect conversion of egg mass to hatchling mass. Incubation temperature did not affect hatchling mass or snout vent length (SVL), but did affect subsequent growth in both mass and SVL, which varied by population. Cooler incubation temperatures generally resulted in greater overall growth over 8 weeks of housing all juveniles in a common environment. In A. carolinensis, egg incubation temperature had latent effects on juvenile growth despite the absence of any detected immediate effects on hatchling phenotype. Therefore, the total impact and evolutionary importance of developmental environment should not be assessed or assumed based solely on the phenotype of reptiles at birth or hatching.

Incubation temperature modifies neonatal thermoregulation in the lizard Anolis carolinensis.

The thermal environment experienced during embryonic development can profoundly affect the phenotype, and potentially the fitness, of ectothermic animals. We examined the effect of incubation temperature on the thermal preferences of juveniles in the oviparous lizard, Anolis carolinensis. Temperature preference trials were conducted in a laboratory thermal gradient within 48 hr of hatching and after 22-27 days of maintenance in a common laboratory environment. Incubation temperature had a significant effect on the upper limit of the interquartile range (IQR) of temperatures selected by A. carolinensis within the first 2 days after hatching. Between the first and second trials, the IQR of selected temperatures decreased significantly and both the lower limit of the IQR and the median selected temperature increased significantly. This, along with a significant incubation temperature by time interaction in the upper limit of the IQR, resulted in a pattern of convergence in thermoregulation among treatment groups. The initial differences in selected temperatures, as well as the shift in selected temperatures between first and second trials, demonstrate plasticity in temperature selection. As a previous study failed to find environmentally induced plasticity in temperature selection in adult A. carolinensis, this study suggests that this type of plasticity is exclusive to the period of neonatal development.

A survey of the parasites of coyotes (Canis latrans) in New York based on fecal analysis.

Coyotes (Canis latrans) have colonized northeastern North America only within the past 10-80 yr. We examined feces of coyotes in 2000-01 at three sites in New York (USA) to survey parasites in the region. Two cestodes, nine nematodes, five protozoa, one trematode, and two arthropods were identified from 145 coyote fecal samples. Parasite component community diversity was higher (n = 16 species) in southern New York than in middle and northern sites (nine species each) and infracommunity species richness was greater in southern New York than at the other sites. These differences may reflect the variable diets of coyotes, as well as recent colonization of the region and the mixing of component communities from expanding coyote populations.