Pseudacris ornata

Number of Pages: 8Integrative BiologyGeological Science

NOCTURNAL ARBOREALITY IN SNAKES IN THE SWAMPLANDS OF THE ATCHAFALAYA BASIN OF SOUTH-CENTRAL LOUISIANA AND BIG THICKET NATIONAL PRESERVE OF SOUTHEAST TEXAS

The southeastern United States is home to a diverse assemblage of snakes, but only one species, the Rough Greensnake (Opheodrys aestivus), is considered specialized for a predominantly arboreal lifestyle. Other species, such as Ratsnakes (genus Pantherophis) and Ribbonsnakes/Gartersnakes (genus Thamnophis), are widely known to climb into vegetation and trees. Some explanations given for snake climbing behavior are foraging, thermoregulation, predator avoidance, and response to flood. Reports of arboreality in snake species typically not associated with life in the trees (such as terrestrial, aquatic, and even fossorial species) usually come from single observations, with no knowledge of prevalence of the behavior. Here, we report on arboreality of snake species detected during 8 years of night surveys in the Atchafalaya Basin of south-central Louisiana and 5+ years of night surveys in Big Thicket National Preserve in southeast Texas. We recorded a total of 1,088 detections of 19 snake species between the two study areas, with 348 detections above ground level (32%). The Rough Greensnake and Western Ribbonsnake (Thamnophis proximus) accounted for nearly 75% of total arboreal detections among the two study areas. However, with one exception, all snake species detected more than once between both study areas had at least one arboreal detection. These observations demonstrate that snakes with widely varying natural histories may be found in the trees at night, and for some species, this behavior may be more common than previously believed

Climate Change and invasibility of the Antarctic benthos

Benthic communities living in shallow-shelf habitats in Antarctica (<100-m depth) are archaic in their structure and function. Modern predators, including fast-moving, durophagous (skeleton-crushing) bony fish, sharks, and crabs, are rare or absent; slow-moving invertebrates are the top predators; and epifaunal suspension feeders dominate many soft substratum communities. Cooling temperatures beginning in the late Eocene excluded durophagous predators, ultimately resulting in the endemic living fauna and its unique food-web structure. Although the Southern Ocean is oceanographically isolated, the barriers to biological invasion are primarily physiological rather than geographic. Cold temperatures impose limits to performance that exclude modern predators. Global warming is now removing those physiological barriers, and crabs are reinvading Antarctica. As sea temperatures continue to rise, the invasion of durophagous predators will modernize the shelf benthos and erode the indigenous character of marine life in Antarctica

The population genetics of the causative agent of snake fungal disease indicate recent introductions to the USA.

Snake fungal disease (SFD; ophidiomycosis), caused by the pathogen Ophidiomyces ophiodiicola (Oo), has been documented in wild snakes in North America and Eurasia, and is considered an emerging disease in the eastern United States of America. However, a lack of historical disease data has made it challenging to determine whether Oo is a recent arrival to the USA or whether SFD emergence is due to other factors. Here, we examined the genomes of 82 Oo strains to determine the pathogen's history in the eastern USA. Oo strains from the USA formed a clade (Clade II) distinct from European strains (Clade I), and molecular dating indicated that these clades diverged too recently (approximately 2,000 years ago) for transcontinental dispersal of Oo to have occurred via natural snake movements across Beringia. A lack of nonrecombinant intermediates between clonal lineages in Clade II indicates that Oo has actually been introduced multiple times to North America from an unsampled source population, and molecular dating indicates that several of these introductions occurred within the last few hundred years. Molecular dating also indicated that the most common Clade II clonal lineages have expanded recently in the USA, with time of most recent common ancestor mean estimates ranging from 1985 to 2007 CE. The presence of Clade II in captive snakes worldwide demonstrates a potential mechanism of introduction and highlights that additional incursions are likely unless action is taken to reduce the risk of pathogen translocation and spillover into wild snake populations

The population genetics of the causative agent of snake fungal disease indicate recent introductions to the USA.

Snake fungal disease (SFD; ophidiomycosis), caused by the pathogen Ophidiomyces ophiodiicola (Oo), has been documented in wild snakes in North America and Eurasia, and is considered an emerging disease in the eastern United States of America. However, a lack of historical disease data has made it challenging to determine whether Oo is a recent arrival to the USA or whether SFD emergence is due to other factors. Here, we examined the genomes of 82 Oo strains to determine the pathogen's history in the eastern USA. Oo strains from the USA formed a clade (Clade II) distinct from European strains (Clade I), and molecular dating indicated that these clades diverged too recently (approximately 2,000 years ago) for transcontinental dispersal of Oo to have occurred via natural snake movements across Beringia. A lack of nonrecombinant intermediates between clonal lineages in Clade II indicates that Oo has actually been introduced multiple times to North America from an unsampled source population, and molecular dating indicates that several of these introductions occurred within the last few hundred years. Molecular dating also indicated that the most common Clade II clonal lineages have expanded recently in the USA, with time of most recent common ancestor mean estimates ranging from 1985 to 2007 CE. The presence of Clade II in captive snakes worldwide demonstrates a potential mechanism of introduction and highlights that additional incursions are likely unless action is taken to reduce the risk of pathogen translocation and spillover into wild snake populations

Nocturnal basking in freshwater turtles: A global assessment

Diurnal basking (“sunning”) is common in many ectotherms and is generally thought to be a behavioural mechanism for thermoregulation. Recent studies have reported the occurrence of nocturnal basking in a few distantly-related species of freshwater turtles, but the true extent of this behaviour is unknown, and it may be underreported due to sampling biases (e.g., not surveying for turtles at night). Therefore, we initiated a global, collaborative effort to systematically document and quantify basking activity (diurnal and nocturnal) across a wide range of freshwater turtle species and locations. We conducted camera trap or manual surveys in North America, the Caribbean, Europe, Asia, Africa, the Seychelles, and Australia. We collected 873,111 trail camera photographs (25,273 hrs of search effort) and obtained data on 29 freshwater turtle species from seven families. Nocturnal basking was documented in 13 species, representing six families (Chelidae, Emydidae, Geoemydidae, Kinosternidae, Pelomedusidae, and Trionychidae), including representatives in Central America, Trinidad and Tobago, Africa, the Seychelles, Asia, and Australia. Nocturnal basking was restricted to tropical and sub-tropical locations, suggesting that environmental temperature plays a role in this behaviour. However, the primary factors driving nocturnal basking are yet to be determined and may vary geographically and by species. The frequency and duration of nocturnal basking varied among species and seasons, but nocturnal basking events were often substantially longer than diurnal events. This is the first study to document a widespread occurrence of nocturnal basking, and our results suggest that nocturnal basking may be a common, although overlooked, aspect of many species’ ecology

Table S2 from Snake fungal disease: an emerging threat to wild snakes

Fungal operational taxonomic units (OTUs) recovered from the skin of snakes. Each unique internal transcribed spacer (ITS) region DNA sequence variant (i.e., 100% identity) was assigned a numerical code and a presumptive taxon identification. The NWHC case number (see table S1) of the host(s) from which each variant was recovered is specified. A representative DNA sequence for each variant has been deposited in GenBank; bolded case numbers depict the snakes from which these deposited fungal DNA sequences originated. The assignment of each ITS variant to an OTU based on cut-offs of 99.5%, 99%, 98%, and 97% sequence identities is shown, with each OTU given an alpha-numeric cod

Table S4 from Snake fungal disease: an emerging threat to wild snakes

Additional samples analyzed by fungal culture to assess the known host range and geographic distribution of Ophidiomyces. Location data is displayed only to the county level due to concerns with disclosing specific locations of rare or sensitive snake populations. The type of growth medium upon which the fungus culture was performed is listed in the last column (DTM = dermatophyte test medium; IMA = inhibitory mold agar; PFA = potato flake agar; SD = Sabouraud's dextrose agar

Table S1 from Snake fungal disease: an emerging threat to wild snakes

Samples used to determine the types of fungi associated with dermatitis in wild snakes. Location data are displayed only to the county (or sometimes state) level due to concerns with disclosing specific locations of rare or sensitive snake populations. Fungal infection was assessed by examining histologic sections of skin lesions. The number of gross lesions consistent with dermatitis were categorized as "none" (no gross skin lesions observed), "single" (one lesion), "multiple" (more than one discrete lesion), or "not assessed" (no information was available on the number of skin lesions present). The type of fungal growth medium upon which samples were cultured is listed as "DTM" (dermatophyte test medium) or "SD" (Sabouraud dextrose medium containing chloramphenicol and gentamycin). The number of unique internal transcribed spacer region DNA sequences identified per snake (or operational taxonomic units [OTUs] at 100% sequence identity) is listed. Samples originating from snakes cited in previous literature are specifie

Batrachochytrium salamandrivorans (Bsal) not detected in an intensive survey of wild North American amphibians.

The salamander chytrid fungus (Batrachochytrium salamandrivorans [Bsal]) is causing massive mortality of salamanders in Europe. The potential for spread via international trade into North America and the high diversity of salamanders has catalyzed concern about Bsal in the U.S. Surveillance programs for invading pathogens must initially meet challenges that include low rates of occurrence on the landscape, low prevalence at a site, and imperfect detection of the diagnostic tests. We implemented a large-scale survey to determine if Bsal was present in North America designed to target taxa and localities where Bsal was determined highest risk to be present based on species susceptibility and geography. Our analysis included a Bayesian model to estimate the probability of occurrence of Bsal given our prior knowledge of the occurrence and prevalence of the pathogen. We failed to detect Bsal in any of 11,189 samples from 594 sites in 223 counties within 35 U.S. states and one site in Mexico. Our modeling indicates that Bsal is highly unlikely to occur within wild amphibians in the U.S. and suggests that the best proactive response is to continue mitigation efforts against the introduction and establishment of the disease and to develop plans to reduce impacts should Bsal establish