New publication: effects of glyphosate and captivity on bacterial microbiota in False Map Turtles

Understanding how environmental factors influence various aspects of freshwater turtle health remains an important yet understudied topic within the context of individual–environment interactions. This is particularly true of hostassociated bacterial microbiota, which are being increasingly recognized as a significant and understudied topic in the context of individual turtle health. While this area of work has expanded in certain areas, research efforts remain limited with regard to host–microbiota interactions in the context of habitat contaminants. Specifically, the commonly used herbicide, glyphosate, is of interest due to its massive worldwide use and known effects on various organisms. Effects of captivity on host-associated microbial community structure also remain largely unknown in various nonmodel organisms. To address these unknown effects of Roundup® and captivity on host-associated microbiomes, we examined the effects of low-level Roundup® exposure and captivity on the cloacal microbiota of the False Map Turtle, Graptemys pseudogeographica. We determined the effect of glyphosate by taking cloacal swabs pre- (0 h) and postexposure (72 h) and examined microbial community beta- and alpha-diversity through 16S rRNA gene high-throughput sequencing. The results of this study indicate that low-level, short-term glyphosate exposure does not significantly alter the microbiota structure of G. pseudogeographica. However, there was a significant decrease in microbial community beta-diversity over time, confirming a trend that has been observed to a limited extent in other non-model organisms when put in laboratory conditions. These results are useful in understanding the baseline cloaca microbial community structure of G. pseudogeographica, as well as the implications and limitations of laboratory-based microbiota studies. Furthermore, this work suggests that low-level and short-term glyphosate exposure does not have a significant effect on the cloacal microbial community structure in wild-caught G. pseudogeographica.

Madison JD, Austin SD*, Davis DR, Kerby JL. 2018. Bacterial microbiota response in Graptemys pseudogeographica to captivity and Roundup® exposure. Copeia 106:580–588. [PDF]


 

Lined Snake surveys completed

Earlier this year I was awarded funding from South Dakota Game, Fish and Parks to survey for the state-endangered Lined Snake (Tropidoclonion lineatum) along the James River in southeastern South Dakota (see earlier post). As part of this survey work, two trips were planned: one trip in the spring corresponding with the the first days of warm temperature and one trip in the fall, corresponding with the final warm days of the year before snakes enter hibernacula. I recently completed the fall survey trip and despite most overcast days, I was able to overlap with an unusually warm day (3 October 2018; 30°C/86°F), and found eight Lined Snakes; unfortunately, all were dead on the road. These specimens were collected as voucher specimens and will be used as reference material and provide tissue samples from this population of Lined Snakes in Hutchinson County to determine if there is gene flow between this population and populations along the Big Sioux River. These eight Lined Snakes, combined with the eight individuals I found during the spring survey period (6 live, 2 dead) confirm an established population of Lined Snakes in this region along the James River. Due to the lack of detection of Lined Snakes outside of this locality, this may be a small, isolated population rather than a large, widespread population along the lower James River. 

New publication: co-infection of Bd and RV in Oklahoma amphibians

Global amphibian decline continues to be a great concern despite our increased understanding of the causes behind the observed patterns of the decline, such as habitat modification and infectious diseases. Although there is a large body of literature on the topic of amphibian infectious diseases, pathogen prevalence and distribution among entire communities of species in many regions remain poorly understood. In addition to these geographic gaps in our understanding, past work has focused largely on individual pathogens, either Batrachochytrium dendrobatidis (Bd) or ranavirus (RV), rather than dual infection rates among host species. We sampled for prevalence and infection load of both pathogens in 514 amphibians across 16 total sites in northeastern Oklahoma. Amphibians were caught by hand, net, or seine; they were swabbed to screen for Bd; and liver tissue samples were collected to screen for RV. Overall results of quantitative PCR assays showed that 7% of screened individuals were infected with RV only, 37% were infected with Bd only, and 9% were infected with both pathogens simultaneously. We also documented disease presence in several rare amphibian species that are currently being  monitored as species of concern due to their small population sizes in Oklahoma. This study synthesizes a growing body of research regarding infectious diseases among amphibian communities in the central United States.

Watters JL, Davis DR, Yuri T, Siler CD. 2018. Concurrent infection of Batrachochytrium dendrobatidis and ranavirus among amphibians from northeastern Oklahoma, USA. Journal of Aquatic Animal Health. doi: 10.1002/aah.10041


 

New Position: Associate Research Scientist at UTRGV

Last week I started in a new position as an Associate Research Scientist at the University of Texas Rio Grande Valley. Here, I am working to better understand factors associated with the distribution of the state-threatened Black-spotted Newt (Notophthalmus meridionalis), sirens, and Rio Grande Cooters (Pseudemys gorzugi) in south Texas. I’m excited to get settled into this position and help increase our understanding of these unique species in the Rio Grande Valley.

When not doing fieldwork, I will be based out of the newly acquired Port Isabel Research Station in Port Isabel, TX.

As part of this position, please note my updated contact information:

Address: 100 Marine Lab Drive, South Padre Island, TX 78597
Email: drew.davis (at) utrgv.edu


 

New publication: new species of Lygosoma from Indochina

Based on molecular and morphological data sets, we describe a new species of scincid lizard of the genus Lygosoma from Indochina, and redescribe true Lygosoma quadrupes (Linnaeus, 1766). The new species is small and slender, and represents the third member of the L. quadrupes complex, increasing the diversity of Lygosoma species recognized in southeast Asia to 24. Based on the reevaluation of vouchered specimens from the type locality of L. quadrupes sensu Linnaeus (1766), the recognized geographic distribution of true L. quadrupes is restricted to the island of Java in Indonesia. With 10 species of Lygosoma recognized in Thailand, the country possesses considerable species-level diversity of these enigmatic, semifossorial skinks. In addition to being one of the smallest species in the genus, the new species can be distinguished from all congeners by features of its external morphology, including having small relative limb lengths, longer trunk length, and greater numbers of axilla–groin and paravertebral scale rows. Phylogenetic analyses support three divergent lineages corresponding to recognized and newly described members of the L. quadrupes complex. The descriptions underscore the need for continued and comprehensive biodiversity survey work throughout much of Southeast Asia, particularly in Indochina, where scincid diversity remains poorly understood.

Siler CD, Heitz BB*, Davis DR, Freitas ES, Aowphol A, Termprayoon K, Grismer LL. 2018. New supple skink, genus Lygosoma (Reptilia: Squamata: Scincidae), from Indochina and redescription of Lygosoma quadrupes (Linnaeus, 1766). Journal of Herpetology 52:332–347. [PDF]


 

Mud Turtle Research: 2018

I recently returned to Washington, DC from my annual trip out to the Chihuahuan Desert of west Texas where I have been collaborating on multiple research projects involving the Yellow Mud Turtle (Kinosternon flavescens). Working with these turtles continuously leaves us asking more questions about their ecology than we are able to answer. We trapped a total of 201 unique Yellow Mud Turtles at five permanent earthen tanks and a few more ephemeral sites that hold water for only a few days after rains. The newest earthen tank, #2, produced no turtles (compared to only a single turtle trapped last year), but numerous turtles were found in all other permanent sites. By the end of our trapping efforts, we were recapturing a high percentage (75–80%) of turtles trapped the preceding days. However, a large rain event (1.3″) at 96 Tank likely resulted in a low recapture percentage (25%), likely due to numerous turtles not seen in over a decade (despite annual trapping efforts at this site) moving to the site from terrestrial burrows.

96 Tank after heavy rains (notice the high turbidity)

Kimball Draw

Adult female Yellow Mud Turtle (Kinosternon flavescens) with an advanced stage of shell disease


 

New publication: 54 new county records for South Dakota

A new publication documenting 54 new distributional records of 17 species of amphibians and reptiles in South Dakota, all collected during 2017, was published in the June 2018 issue of Herpetological Review. Included are numerous records of Boreal Chorus Frogs (n=8) and Painted Turtles (n=8). Also included are six new records of Northern Leopard Frogs, a species for which there is now vouchered material from every county in the state. These specimens are verifiable records of species presence and serve as vouchered material from a historically under-sampled state. All records have been added to the Amphibians and Reptiles of South Dakota website and help fill gaps in the distributions of species across the state.

Davis DR, Farkas JK. 2018. New county records of amphibians and reptiles from South Dakota, USA from 2017. Herpetological Review 49:288–295. [PDF]


 

New publication: South Dakota Conservation Digest article

This spring I was asked to write an article about my efforts in mapping amphibians and reptiles across South Dakota. Since 2012, I have collected voucher specimens and photographs of amphibians and reptiles that I encountered at research study sites, during camping trips, driving down county roads, and pretty much every other time I was outdoors when it wasn’t winter. These records represent a significant increase (>60%) in the number of verifiable records from the state and provide much needed voucher material for current and future studies. While I continue to collect voucher specimens from the state, citizen scientists are also contributing to what is known about distributions of species in the state. In 2017, I launched a new website, Amphibians and Reptiles of South Dakota (http://www.sdherps.org), and have encouraged citizen scientists to submit their own observations of amphibians and reptiles they encounter while outdoors. In 2017, over 900 records were added to http://www.sdherps.org, all of which help to better map species distributions in the state. Hopefully even more records are submitted to the website in 2018.

Davis DR. 2018. Mapping amphibians and reptiles in South Dakota. South Dakota Conservation Digest 85:34–37. [PDF]


 

Funding awarded to survey for endangered Lined Snakes in South Dakota

Today I received notice that I was awarded a Wildlife Diversity Small Grant from South Dakota Game, Fish and Parks to survey for the state-endangered Lined Snake (Tropidoclonion lineatum)Within South Dakota, the Lined Snake was thought to occur only in habitats along the Big Sioux River watershed, until I collected a specimen was collected near the James River in Hutchinson County in October 2017. This recently collected snake represents the most northwestern occurrence for this species, provides evidence that populations of Lined Snakes may exist outside of the Big Sioux River watershed, and suggests that the distribution of Lined Snakes in South Dakota may be greater than expected. To better understand the distribution and occurrence of Lined Snakes in southeastern South Dakota, I proposed to conduct a series of targeted surveys for Lined Snakes along the lower James River valley.

Grant Title: Surveys for the state-endangered Lined Snake (Tropidoclonion lineatum) along the lower James River Valley

Lined Snake distribution map from http://www.sdherps.org.


New publication: Eastern Hog-nosed Snake distribution note

DRD3404.jpegI recently discovered a preserved Eastern Hog-nosed Snake (Heterodon platirhinos) from Brule County, South Dakota (pictured) that represents an important distributional record in the state. Heterodon platirhinos was historically known from southeastern South Dakota in Union and Clay counties. This specimen, from Chamberlain, is roughly 300 km up the Missouri River from previously known localities in Clay County, South Dakota. This historic specimen, combined with recent observations of H. platirhinos from western South Dakota (see https://www.herpmapper.org/record/193175) suggest this species may be present in additional localities across the state and further surveys for this state-threatened species should be a conservation priority.

Davis DR. 2018. Geographic distribution: USA, South Dakota, Brule Co.: Heterodon platirhinos (Eastern Hog-nosed Snake). Herpetological Review 49:76. [PDF]