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The article discusses the first observation of Tropidophis boulengeri mating in the field, providing detailed information on the mating behavior of this snake species. The study was conducted in Ecuador, and the mating behavior was observed near a small forest stream. The article highlights the importance of further research to understand the reproductive patterns and ecology of Tropidophis boulengeri and other snakes in the Ecuadorian Chocó region. [Extracted from the article]

Coevolution between two species can lead to exaggerated phenotypes that vary in a correlated manner across space. However, the conditions under which we expect such spatially varying coevolutionary patterns in polygenic traits are not well understood. We investigate the coevolutionary dynamics between two species undergoing reciprocal adaptation across space and time using simulations inspired by the Taricha newt/ Thamnophis garter snake system. One striking observation from this system is that newts in some areas carry much more tetrodotoxin than in other areas, and garter snakes that live near more toxic newts tend to be more resistant to this toxin, a correlation seen across several broad geographic areas. Furthermore, snakes seem to be "winning" the coevolutionary arms race, that is, having a high level of resistance compared with local newt toxicity, despite substantial variation in both toxicity and resistance across the range. We explore how possible genetic architectures of the toxin and resistance traits would affect the coevolutionary dynamics by manipulating both mutation rate and effect size of mutations across many simulations. We find that coevolutionary dynamics alone were not sufficient in our simulations to produce the striking mosaic of levels of toxicity and resistance observed in nature, but simulations with ecological heterogeneity (in trait costliness or interaction rate) did produce such patterns. We also find that differences in polygenicity do not seem sufficient to explain the observation that snakes seem to be winning. [ABSTRACT FROM AUTHOR]

Finger vein recognition represents an important biometric attribute that is viewed as reliable, emerging, and secure. Finger veins possess the benefit that they are less vulnerable to determining theft since veins are found below the layer of skin, and are also not influenced by the natural aging of the user. The present advanced methods are capable of offering acceptable efficiency. However, they depend on the nature of the processed finger-vein data. Thus, in this paper, by employing deep learning, an intelligent finger vein pattern-based authentication model is introduced. In the beginning, images are accumulated from global resources. Further, the accumulated finger vein images are provided to the introduced Adaptive Vision Transformer-based Multi-scale EfficientNetB7 (AViTMENetB7) network for authentication purposes. This network helps to boost the safety and robustness of the model. Here, the Improved Garter Snake Optimization Algorithm (IGSOA) is introduced to reduce the computational complexity and increase the functionality rates. In the end, by contrasting the implemented vein-based authentication model with traditional vein-based authentication models, the numerical analysis is conducted. [ABSTRACT FROM AUTHOR]

Heterogeneous environments provide different daily and seasonal thermal conditions for snakes, resulting in temporal and spatial variations in body temperature (Tb). This study analyzes the Tb of Thamnophis eques in the forest and grassland of a Mexican locality through daily and seasonal profiling. The patterns were obtained from seminatural enclosures in the field with a point sampling strategy to analyze temporal and spatial variations in Tb. The variation of Tb throughout the day was correlated with air and substrate temperatures, both in the grassland and in the forest. The average Tb in the grassland was 0.88 °C greater than in the forest. Our results indicate that T. eques showed differences in Tb between grassland and forest, principally in late spring and early summer during the early rise and late plateau phases, coinciding with the presence of foliage on the willow trees present in the study area, while in late summer and early autumn, the Tb was similar when willow trees canopy cover was absent (May–September). Our results support the hypothesis that the Tb of snakes differ between forests when the willows have leaves and is similar when canopy cover is equivalent, in this case, when tree canopy cover was absent. Our results also shown that T. eques presented daily and seasonal warming patterns similar to other Arizona populations and like those of other northern Gartersnakes. However, this result may not be valid for the entire wide distribution and consequent diversity of habitats of T. eques. The information of Tb in T. eques through daily and seasonal profiles in different habitats could aid in understanding the effects of environmental conditions on the ecological strategies deployed by snakes on habitat selection. [ABSTRACT FROM AUTHOR]

Protected areas (PAs) are geographical spaces intended to conserve populations, communities, and ecosystems, in which species richness must be maximized, the conserved area must be minimized, and anthropogenic pressure must be reduced. The present study analyzed the representativeness, complementarity, and degree of risk of 25 garter snake species of the genus Thamnophis in the PAs of Mexico. This study proposes that at least 17% of the potential geographic distribution (PGD) of species will be found inside PAs and in areas (Aichi Target 11) with a low human footprint (HF). The PGD of species was associated with the PAs and HF layers to identify where and which species could be at local extirpation risk by human activities. The results indicate that the federal PAs contain 85.2% of the species, while the state PAs contain 77.7% of the species. An average of 13.4% of the PGD of these species is found inside PAs, and two species are found outside. In 13 federal PAs and 10 state PAs, the Thamnophis species present high local extirpation risk from human activities. In total, 37% of species are found in PAs with a medium to very high human footprint; therefore, their persistence could be at local extirpation risk. Compared to other taxa, species of the genus Thamnophis are well represented. However, the PDG of more than half of the species achieves Aichi Target 11. [ABSTRACT FROM AUTHOR]

Animals that consume toxic diets provide models for understanding the molecular and physiological adaptations to ecological challenges. Garter snakes (Thamnophis) in western North America prey on Pacific newts (Taricha), which employ tetrodotoxin (TTX) as an antipredator defense. These snakes possess mutations in voltage-gated sodium channels (Nav), the molecular targets of TTX, that decrease the binding ability of TTX to sodium channels (target-site resistance). However, genetic variation at these loci that cannot explain all the phenotypic variation in TTX resistance in Thamnophis. We explored a separate means of resistance, toxin metabolism, to determine if TTX-resistant snakes either rapidly remove TTX or sequester TTX. We examined the metabolism and distribution of TTX in the body (toxicokinetics), to determine differences between TTX-resistant and TTX-sensitive snakes in the rates at which TTX is eliminated from organs and the whole body (using TTX half-life as our metric). We assayed TTX half-life in snakes from TTX-resistant and TTX-sensitive populations of three garter snake species with a coevolutionary history with newts (T. atratus, T. couchii, T. sirtalis), as well as two non-resistant "outgroup" species (T. elegans, Pituophis catenifer) that seldom (if ever) engage newts. We found TTX half-life varied across species, populations, and tissues. Interestingly, TTX half-life was shortest in T. elegans and P. catenifer compared to all other snakes. Furthermore, TTX-resistant populations of T. couchii and T. sirtalis eliminated TTX faster (shorter TTX half-life) than their TTX-sensitive counterparts, while populations of TTX-resistant and TTX-sensitive T. atratus showed no difference rates of TTX removal (same TTX half-life). The ability to rapidly eliminate TTX may have permitted increased prey consumption, which may have promoted the evolution of additional resistance mechanisms. Finally, snakes still retain substantial amounts of TTX, and we projected that snakes could be dangerous to their own predators days to weeks following the ingestion of a single newt. Thus, aspects of toxin metabolism may have been key in driving predator–prey relationships, and important in determining other ecological interactions. [ABSTRACT FROM AUTHOR]

Temperature is closely linked to the various lifestyles of reptiles, considerably influencing many aspects of their behaviour. Species with contrasting foraging modes or associated with different microhabitats are expected to thermoregulate in distinct ways. We sought to describe the thermal ecology of three model snake species, highlighting how their distinct lifestyles account for variation in thermoregulatory strategies. We chose the fossorial Conopsis lineata , the terrestrial Crotalus polystictus , and the semi-aquatic Thamnophis melanogaster. Following the protocol proposed by Hertz et al. (1993), we gathered data on body and operative temperatures in the field and preferred temperatures ( T set ) in the laboratory. The three species exhibited a wide range of T set , with differences between lower and upper limits ranging from 6.4°C to 8°C. The E index of effectiveness of thermoregulation was 0.685 for C. polystictus , 0.644 for C. lineata , and 0.486 for T. melanogaster. These results indicate that C. lineata and C. polystictus are precise and active thermoregulators. C. lineata has cryptic and fossorial habits, and we propose that its efficient thermoregulation likely results from the strategic selection of thermally favourable retreat sites. Contrary to what we predicted, T. melanogaster turned out to be the least accurate thermoregulator. Its semiaquatic lifestyle can help it to maintain beneficial body temperatures with less effort since aquatic environments are more thermally homogeneous. Overall, our study shows that lifestyle affects thermoregulation to an extent in these species, but that the thermal environments they inhabit also plays a key role in delimiting their thermoregulatory strategies. [ABSTRACT FROM AUTHOR]

Well-documented natural history allows for thorough study of a species' ecology and evolution. However, inadequate natural history data hamper such studies for many species. For example, diet plays a major role in the evolution of species and traits, but thorough quantitative dietary information is often lacking for many groups. Garter snakes (Thamnophis) have been used as model organisms for numerous studies, including many focused on feeding ecology and evolution, but these studies lack a thorough compilation of dietary records. To fill the substantial natural history gap, we amassed nearly 10,000 dietary records for 32 of 35 Thamnophis species, from more than 150 sources, and classified each species' dietary repertoire. We categorized 15 of 32 species as generalist predators and 17 of 32 species as specialist predators of varying prey groups, presenting novel dietary classifications for 15 species. Additionally, we investigated the hypothesis that generalist predators have larger body size, a pattern shown in other snake communities and lineages. However, we found no significant relationship between body size and dietary specialization in the genus. Our findings add to the knowledge of natural history, ecology, and evolution of Thamnophis and provide access to the largest dietary record repository for the genus to date. [ABSTRACT FROM AUTHOR]

An early detection of lung tumors is critical for better treatment results, and CT scans can reveal lumps in the lungs which are too small to be picked up by conventional X-rays. CT imaging has advantages, but it also exposes a person to radiation from ions, which raises the possibility of malignancy, particularly when the imaging procedure is done. Access to expensive-quality CT scans and the related sophisticated analytic tools might be restricted in environments with fewer resources due to their high cost and limited availability. It will need an array of creative technological innovations to overcome such weaknesses. This paper aims to design a heuristic and deep learning-aided lung cancer classification using CT images. The collected images are undergone for segmentation, which is performed by Shuffling Atrous Convolutional (SAC) based ResUnet++ (SACRUnet++). Finally, the lung cancer classification is performed by the Adaptive Residual Attention Network (ARAN) by inputting the segmented images. Here the parameters of ARAN are optimally tuned using the Improved Garter Snake Optimization Algorithm (IGSOA). The developed lung cancer classification performance is compared to conventional lung cancer classification models and it showed high accuracy. [ABSTRACT FROM AUTHOR]

Nearly one in five reptile species is at risk of extinction. Changes in habitat area, its configuration, and vegetation diversity could affect habitat use, but their relative importance is understudied. We assessed how these factors affected reptile presence in agricultural landscapes figure in Iowa, United States, using 695 cover boards visited 16,441 times in 2015–2020. Species‐wise encounter rates ranged 0.0001–0.012. Eight of 11 species and 54.2% of individuals were species of greatest conservation need. Habitat area, configuration, and vegetation diversity influenced reptile presence similarly. Mean patch occupancy was 0.18 for common garter snake (CG, Thamnophis sirtalis) and 0.45 for all snakes (AS). Naïve presence was explained by effort (odds ratio [OR]AS = 1.83, ORCG = 1.79), vegetation diversity (ORAS = 1.28, ORCG = 1.28), woody cover (ORAS = 1.24, ORCG = 1.41), and patch size (ORAS = 1.30). Large patch prairies were more likely to contain snakes than other conservation practices (r̂encounter = 0.291), and more likely to contain CG (0.098) than prairie contour strips (0.031), waterways (0.018), grass contour strips (0.016), or terraces (0.015). While we documented low overall reptile presence, their higher presence in large prairie patches underscores the importance of core nature reserves for reptile conservation. [ABSTRACT FROM AUTHOR]

Wildlife populations at the peripheries of their distributions or on isolated islands often display divergent and poorly understood morphological or life-history characteristics compared to core populations. We used a capture–mark–recapture dataset collected over a 19-year period to characterize a northern, insular snake assemblage in coastal Maine. We captured 611 individual snakes of 4 species (Thamnophis sirtalis [Common Gartersnake; n = 221 individuals], Diadophis punctatus [Ring-necked Snake; n = 258 individuals], Storeria occipitomaculata [Red-bellied Snake; n = 81 individuals], and Opheodrys vernalis [Smooth Greensnake; n = 51 individuals]) and recorded 104 recaptures. We provide some of the first data on growth, reproduction, and movement for these species in northern New England, expanding our understanding of insular and northern snake populations. Specifically, we found that Common Gartersnakes fed primarily on earthworms and amphibians and grew rapidly, in accordance with mainland populations, but exhibited smaller size at maturity and average litter sizes. We captured an unusually large number of Ring-necked Snakes, which are uncommon elsewhere in Maine, and recorded an apparently localized nesting area for this species, as well as relatively long-distance (230–300 m) dispersal away from that location. In our population, female Ring-necked Snakes mature in their third year, and this species exhibits weak sexual size dimorphism (SSD). We found the ecology of Red-bellied Snakes at our study site to be similar to other populations, with individuals feeding on slugs, and females maturing in their second year; however, our population exhibited the strongest pattern of (female-biased) SSD. Smooth Greensnakes were restricted to the most extensive old-field habitat within our study site and fed on a variety of arthropods. We confirmed communal nesting and short incubation period for this species and provide among the first data on growth and longevity (at least 7 years) of this relatively understudied species. [ABSTRACT FROM AUTHOR]

Pre-release training is becoming a standard practice in conservation breeding and translocation programs for mammals and birds, but is still relatively neglected for herpetofauna, likely stemming from widespread beliefs that amphibians are “hardwired” and are thus predicted to benefit little from experiential learning. However, experience during development can drive both morphological and behavioral modifications that could benefit post-translocation survival. Here, we developed an antipredator training program for the endangered mountain yellow-legged frog Rana muscosa and evaluated its impact on morphometrics, developmental rates, behavior, and post-release outcomes. Using a controlled, balanced factorial experimental design, we exposed individuals at two developmental stages (tadpoles and postmetamorphic) to visual and olfactory cues from one of its principal predators, the two-striped garter snake Thamnophis hammondii. We found that exposure to predators during the tadpole stage impacted tadpole development, morphology, and behavior. However, we found no evidence that post-metamorphic behavior or postrelease outcomes were influenced by tadpole predator exposure, either on its own or in interaction with post-metamorphic training treatments. Training of postmetamorphic frogs, however, yielded evidence of learning, with downstream effects on behavior and apparent survival after release into the wild. Our findings produce novel insights on the value of anti-predator training in amphibian conservation translocation programs, bolster recent evidence re-evaluating the importance of learning and developmental experience for amphibian species, and provide guidance for selecting optimal developmental windows for training. [ABSTRACT FROM AUTHOR]

Sex- and age-based social structures have been well documented in animals with visible aggregations. However, very little is known about the social structures of snakes. This is most likely because snakes are often considered non-social animals and are particularly difficult to observe in the wild. Here, we show that wild Butler's Gartersnakes have an age and sex assorted social structure similar to more commonly studied social animals. To demonstrate this, we use data from a 12-year capture-mark-recapture study to identify social interactions using social network analyses. We find that the social structures of Butler's Gartersnakes comprise sex- and age-assorted intra-species communities with older females often central and age segregation partially due to patterns of study site use. In addition, we find that females tended to increase in sociability as they aged while the opposite occurred in males. We also present evidence that social interaction may provide fitness benefits, where snakes that were part of a social network were more likely to have improved body condition. We demonstrate that conventional capture data can reveal valuable information on social structures in cryptic species. This is particularly valuable as research has consistently demonstrated that understanding social structure is important for conservation efforts. Additionally, research on the social patterns of animals without obvious social groups provides valuable insight into the evolution of group living. [ABSTRACT FROM AUTHOR]

Resource allocation and hormone provisioning during vitellogenesis has been documented for many oviparous reptiles, while viviparous species remain relatively understudied in the context of yolk composition. Squamates that have evolved viviparity have retained varying degrees of embryonic nourishment via the yolk (lecithotrophy). Very little is known about the timing of embryonic hormone production, and the degree of maternal hormone provisioning in viviparous reptiles. Viviparous species may, in principle, receive hormone exposure through some or all of three routes, viz., maternal provisioning in the yolk, transfer from the maternal circulation, and/or hormone production by the developing embryonic endocrine tissues. In toad-eating snakes, adrenal hormones may provide protection from toad toxins, supplementing genetic resistance. Additionally, one species of oviparous snake has been shown to provision its embryos with defensive toxins from toads. We hypothesized that embryonic hormone levels would increase during development and that yolk hormone levels would correspondingly decrease. We also predicted that the embryos from females administered toad toxin would have higher levels of corticosterone (CORT) in response to exposure to a toad toxin. We measured levels of CORT in the embryos and corresponding yolks of a viviparous and genetically toxin-resistant natricine, the Western Terrestrial Garter Snake (Thamnophis elegans), beginning at Zehr Stage 26. We found that embryos and their corresponding yolks had relatively higher levels of CORT in later stages. There were no measurable differences in CORT between embryos of the same stage obtained from dams treated with marinobufagenin (MBG) or no treatment. Given that yolk and embryonic CORT increase throughout the course of development, a trade-off between early maternal provisioning and the onset of adrenal function is not apparent. However, increase in adrenal production of CORT over the course of development remains relevant to both stress physiology and physiological toxin resistance. [ABSTRACT FROM AUTHOR]

For endangered species persisting in a few populations, reintroductions to unoccupied habitat are a popular conservation action to increase viability in the long term. Identifying the reintroduction strategy that is most likely to result in viable founder and donor populations is essential to optimally use resources available for conservation. The San Francisco gartersnake (Thamnophis sirtalis tetrataenia) is an endangered sub-species that persists in a small number of populations in a highly urbanized region of California. Most of the extant populations of San Francisco gartersnakes have low adult abundance and effective population size, heightening the need for establishment of more populations for insurance against the risk of extinction. We used simulations from demographic models to project the probability of quasi-extinction for reintroduced populations of San Francisco gartersnakes based on the release of neonate, juvenile, adult, or mixed-age propagules. Our simulation results indicated that the release of head-started juveniles resulted in the greatest viability of reintroduced populations, and that releases would need to continue for at least 15 years to ensure a low probability of quasi-extinction. Releasing captive-bred juvenile snakes would also have less effect on the viability of the donor population, compared to strategies that require more adult snakes to be removed from the donor population for translocation. Our models focus on snake demography, but the genetic makeup of donor, captive, and reintroduced populations will also be a major concern for any proposed reintroduction plan. This study demonstrates how modeling can be used to inform reintroduction strategies for highly imperiled species. [ABSTRACT FROM AUTHOR]

Non-native species have numerous and significant, often negative, effects on amphibians, but that threat may be ameliorated if the native species is able to respond behaviourally to the non-native predators. We experimentally compared the behavioural response of tadpoles of the Ridged Tree Frog, Dryophytes plicatus , to cues from non-native Rainbow Trout, Oncorhynchus mykiss , to those to a native predator, the Short-tail Alpine Garter Snake, Thamnophis scaliger. Dryophytes plicatus tadpoles did not alter activity in response to cues from O. mykiss but increased activity in the presence of cues from T. scaliger , although it is possible this increase is related, at least in part, to the order of the presentation of the cues. The activity of D. plicatus tadpoles was higher in the absence of the vegetation than in its presence when exposed to predator cues, both T. scaliger and O. mykiss , but not in the control. In conclusion, our results show D. plicatus tadpoles alter their overall activity when exposed to cues from a native predator, T. scaliger , but not the non-native O. mykiss. These results may explain, in part, why D. plicatus can co-occur with T. scaliger but not O. mykiss. [ABSTRACT FROM AUTHOR]

The Mexican gartersnake (Thamnophis eques) is a federally threatened species in the United States, with only a few isolated populations remaining in Arizona and New Mexico. For some populations, only limited knowledge exists regarding their status and natural history; thus, all observations are noteworthy. Along the Gila River in New Mexico, for example, only 2 observations of this species have been published, one in 1883 and one in 1973. Herein, I report on 6 additional observations of Mexican gartersnakes from along the Gila River in southwestern New Mexico. Five indi¬viduals were documented in riparian habitats close to or in water, but one was observed in more arid habitats away from riparian habitats. Two individuals were found dead on paved roadways, demonstrating that mortality along roads is a threat to this limited population that generally is associated only with wetland habitats. Further surveys are warranted in the area to better understand the status and habitats used by this rare species in the region. [ABSTRACT FROM AUTHOR]

Antagonistic coevolution between natural enemies can produce highly exaggerated traits, such as prey toxins and predator resistance. This reciprocal process of adaptation and counter‐adaptation may also open doors to other evolutionary novelties not directly involved in the phenotypic interface of coevolution. We tested the hypothesis that predator–prey coevolution coincided with the evolution of conspicuous coloration on resistant predators that retain prey toxins. In western North America, common garter snakes (Thamnophis sirtalis) have evolved extreme resistance to tetrodotoxin (TTX) in the coevolutionary arms race with their deadly prey, Pacific newts (Taricha spp.). TTX‐resistant snakes can retain large amounts of ingested TTX, which could serve as a deterrent against the snakes' own predators if TTX toxicity and resistance are coupled with a conspicuous warning signal. We evaluated whether arms race escalation covaries with bright red coloration in snake populations across the geographic mosaic of coevolution. Snake colour variation departs from the neutral expectations of population genetic structure and covaries with escalating clines of newt TTX and snake resistance at two coevolutionary hotspots. In the Pacific Northwest, bright red coloration fits an expected pattern of an aposematic warning to avian predators: TTX‐resistant snakes that consume highly toxic newts also have relatively large, reddish‐orange dorsal blotches. Snake coloration also seems to have evolved with the arms race in California, but overall patterns are less intuitively consistent with aposematism. These results suggest that interactions with additional trophic levels can generate novel traits as a cascading consequence of arms race coevolution across the geographic mosaic. see also the Perspective by John N. Thompson [ABSTRACT FROM AUTHOR]

A 10‐month‐old female, neutered French Bulldog presented with a history of unilateral right‐sided intermittent conjunctivitis and exophthalmos. The patient suffered blunt force trauma to the right eye after a tennis ball impact approximately five months prior to presentation. Examination identified the patient was visual with exophthalmos, lateral strabismus, conjunctival hyperaemia, episcleral congestion, and papilloedema. Magnetic resonance imaging and ultrasonography identified an approximately two centimeter diameter fluid‐filled structure directly posterior to the globe leading to displacement of the optic nerve and distortion of the posterior globe wall. Centesis of the lesion demonstrated neutrophilic and macrophagic inflammation with evidence of prior hemorrhage. Within four weeks, the structure had re‐filled to its original size and was subsequently excised in its entirety, via a lateral orbitotomy. Histopathologic findings indicated a non‐keratinising orbital cyst, the lining of which was consistent with a respiratory epithelial cyst. Recurrence had not occurred seven months' post‐surgery. To the author's knowledge, previous reports of retrobulbar respiratory epithelial cysts have not been documented in animals. [ABSTRACT FROM AUTHOR]

Plethodontid salamanders often possess the ability to detect and avoid hazards in the environment which may be important for survival. We examined whether the two main colour morphs of Plethodon cinereus differ in their avoidance of cues from a potential predator (Thamnophis sirtalis) and whether P. cinereus avoided cues from T. sirtalis of different sizes (i.e., small vs. large). Plethodon cinereus avoided chemical cues deposited by T. sirtalis on a substrate; but avoidance did not differ between colour morphs of P. cinereus , snake sizes, or individual donor snakes. [ABSTRACT FROM AUTHOR]

The greatest driver of the current biodiversity crisis is habitat loss. Roads are a major contributor to habitat loss because they destroy and fragment habitat, in addition to causing direct mortality. Animals may respond to roads either by avoiding them, thus leading to population isolation, or by attempting to cross them, thus potentially leading to increased mortality and, if so, also to population isolation. We studied the impact of road density on abundance of two snake species: redbelly snakes (Storeria occipitomaculata Storer, 1839) and garter snakes (Thamnophis sirtalis Linnaeus, 1758) around Ottawa, Canada. We hypothesized that roads are detrimental to snake populations due to road avoidance and mortality. Therefore, we predicted that snakes should be less abundant at sites with higher road density in their surroundings. We deployed cover boards at 28 sites along a gradient of road density in 2020 and 2021. We visited sites weekly, counted the number of individuals of both species, and measured snout–vent length (SVL) of all individuals captured. We captured fewer garter snakes at sites surrounded by more roads and fewer redbelly snakes at sites surrounded by more urban habitat. Snakes at sites surrounded by more roads were not smaller. The effects of roads and urbanization on the number of snakes were modest, but indicate decreasing population sizes that could lead to loss of ecological function. [ABSTRACT FROM AUTHOR]

Many imperiled species face increasing extinction risk that requires interventional management like translocation or captive rearing. The use of translocations to successfully restore or create populations requires that animals survive at recipient sites, information that is often lacking for imperiled species and that can be risky to acquire if not obtained before a species has dwindled in number. The giant gartersnake (Thamnophis gigas), a semiaquatic snake endemic to the Central Valley in California, USA, has declined after losing >90% of its historical habitat and may benefit from successful translocations to protected habitat. We released adult and captive‐reared juvenile snakes from 2 donor sites into a recently restored wetland in 2019 and 2020 and compared their survival, movement, and activity using radio‐telemetry through 2021. We monitored juvenile survival for 2 years in captivity after birth and then estimated post‐release survival at the recipient site using radio‐telemetry. Just 8% of translocated adult snakes survived >801 days (95% CI = 1–64%) compared with 39% of resident snakes at the donor sites surviving >1,154 days (95% CI = 23–68%). This equated to annualized survival rates of translocated adults (x¯ $\bar{x}$ = 0.32, 95% CI = 0.12–0.82) that were roughly half that of resident snakes (x¯ $\bar{x}$ = 0.74, 95% CI = 0.63–0.89). Translocation was negatively correlated with survival, but movement and activity received little support in models. Seventy‐six percent of juvenile snakes survived captivity and, once released, juvenile survival was 60% (95% CI = 38–94%) for the 4‐month monitoring period before winter. It is unclear why survival of translocated adult snakes was lower than that of resident snakes, but there was little evidence for differences in behavior (e.g., increased surface activity, average distance moved, emigration from the translocation site) that are commonly cited causes of mortality in other translocation studies. Our results suggest that, in the absence of a clear understanding as to what contributes to adult survival after release to a new site, future work using captive‐rearing and juvenile translocation may be more promising for establishing and recovering populations than just translocating adults given the high survival of juveniles. [ABSTRACT FROM AUTHOR]

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Enterocytozoon bieneusi belongs to the phylum Microsporidia, a parasite reported to infect various domestic animals, wildlife and humans, thereby causing an intestinal disease characterized by severe or chronic diarrhea and malabsorption. The typical mode of transmission is contaminated water and food. Few studies on E. bieneusi infections have been reported in reptiles, however, our report focuses on the molecular characterization of E. bieneusi infection in snakes in China. We collected a total of 603 fecal samples from snakes in China. The samples were tested for the presence of E. bieneusi through PCR amplification of the internal transcribed spacer (ITS) locus. Our analysis showed E. bieneusi overall prevalence rate of 15.59 %, the highest prevalence was recorded in Eastern rat snake (21.99 %), followed by Corn snake (19.63 %) while the prevalence of 18.39 %, 15.79 %, 13.56 % were recorded in Common garter snake, Pine snake, Hognose snake respectively. Eastern kingsnake has the lowest infection rate of 5.71 %. Genotype analysis identified 26 distinct genotypes: 8 known and 18 novel. Phylogenetic analysis revealed that 25 genotypes belonged to Group 1, which includes isolates from various animal hosts and humans. However, genotype GX29 was classified under Group 9. Our study indicates that pet snakes are one of the potential sources of transmission of zoonotic microsporidiosis in China. [Display omitted] • 15.59 % of snakes tested PCR positive for Enterocytozoon bieneusi in China. • Genotype analysis identified 26 genotypes: 8 known and 18 new genotypes. • E. bieneusi infected snakes are a potential source of zoonotic microsporidiosis. [ABSTRACT FROM AUTHOR]

Intraspecific phenotypic variation can be used as a window into the ecological differences among individuals of a species and lead to a better understanding of adaptive evolution. Adaptive traits, such as venom, that play an important ecological role for a species are useful models for understanding the sources of intraspecific variation. Intraspecific studies on front-fanged venomous snakes have offered deeper insights into the diverse mechanisms and adaptations that support the effectiveness of venom across species. Despite the extensive research on front-fanged venomous snakes, rear-fanged snakes, representing two-thirds of all snake species, have been largely overlooked. To test for sex and age-based intraspecific venom variation, we sequenced the messenger RNA from the Duvernoy's gland of 9 male and 10 female Common Garter Snakes, Thamnophis sirtalis , of different sizes from a single location. Our data represent the most venom gland transcriptomes of any venomous snake species from a single location and represent the first Duvernoy's venom gland transcriptomes for Thamnophis sirtalis. We found four toxin families dominate the Thamnophis sirtalis transcriptome: Snake Venom Metalloproteinases (SVMPs), Three-finger toxins (3FTxs), Cysteine-Rich Secretory Proteins (CRISPs), and C-type lectins (CTLs). Thamnophis sirtalis exhibits a unique balance in toxin expression, with approximately 30% each of neurotoxic (3FTx-dominated) and enzymatic (SVMP-dominated) components. No other published RFS Duvernoy's gland transcriptome displays this ratio, rather they are dominated by one or the other. Additionally, venom expression varies with sex and size, with differences in toxin gene expression between males and females as they grow. Our study provides new insights on venom composition in a RFS species and highlights the amount of intraspecific variation possible among individuals from a single population. [Display omitted] • Characterization of the first Thamnophis sirtalis rear-fanged snake venom gland transcriptome. • Description of Thamnophis sirtalis intraspecific variation observed in the largest collection of transcriptomes from a single snake population. • Identification of a similar ratio of neurotoxins and enzymatic toxins observed in Thamnophis sirtalis venom gland. [ABSTRACT FROM AUTHOR]

Sex steroid hormones are powerful regulators of reproductive behavior and physiology in vertebrates, and steroidogenesis has distinct sex- and seasonspecific patterns ultimately dictated by the expression of key enzymes. Most comparative endocrinology studies, however, focus only on circulating levels of sex steroids to determine their temporal association with life-history events in what are termed associated reproductive patterns. The red-sided garter snake (Thamnophis sirtalis parietalis) is a notable exception; this species exhibits maximal sex behavior decoupled from maximal sex steroid production and gametogenesis in what is termed a dissociated reproductive pattern. And while this is true for male red-sided garter snakes and their production of testosterone, females have maximal estradiol production during peak breeding (spring) but only immediately after mating. Here, we demonstrate that expression of ovarian aromatase (conversion of androgens to estrogens) matches the established seasonal hormone pattern in females. Additionally, steroidogenic gene expression in the ovary is broadly reduced if not suppressed compared to the testis throughout the active year. Bizarrely, male red-sided garter snakes demonstrate an unexplained pattern of steroidogenic gene expression in the testis. StAR (import of cholesterol to steroidogenesis) is maximally expressed in spring, yet Hsd17b3 expression (conversion of androstenedione to testosterone) is highest in summer, with the latter matching the established summer peak in male testosterone. The function of elevated StAR in spring is unknown, but our results suggest a decoupling between maximal StAR expression and testosterone biosynthesis (Hsd17b3 expression). We also purport that the reproductive pattern binary should be reassessed given its lack of fit for many vertebrate species that demonstrate seasonal, mixed patterns of (a)synchrony between circulating sex hormones and reproductive behavior. [ABSTRACT FROM AUTHOR]

The presentation, etiology, and relative risk of psychiatric disorders are strongly influenced by biological sex. Neuroticism is a transdiagnostic feature of psychiatric disorders displaying prominent sex differences. We performed genome-wide association studies of neuroticism separately in males and females to identify sex-specific genetic and transcriptomic profiles. Neuroticism scores were derived from the Eysenck Personality Inventory Neuroticism scale. Genome-wide association studies were performed in 145,669 females and 129,229 males from the UK Biobank considering autosomal and X chromosomal variation. Two-sided z tests were used to test for sex-specific effects of discovered loci, genetic correlates (n = 673 traits), tissue and gene transcriptomic profiles, and polygenic associations across health outcomes in the Vanderbilt University Biobank (39,692 females and 31,268 males). The single nucleotide polymorphism heritability of neuroticism was not statistically different between males (h 2 = 10.6%) and females (h 2 = 11.85%). Four female-specific (rs10736549- CNTN5 , rs6507056- ASXL3 , rs2087182- MMS22L , and rs72995548- HSPB2) and 2 male-specific (rs10507274- MED13L and rs7984597) neuroticism risk loci reached genome-wide significance. Male- and female-specific neuroticism polygenic scores were most significantly associated with mood disorders (males: odds ratio = 1.11, p = 1.40 × 10−9; females: odds ratio = 1.14, p = 6.05 × 10−22). They also associated with sex-specific laboratory measurements related to erythrocyte count, distribution, and hemoglobin concentration. Gene expression variation in the pituitary was enriched for neuroticism loci in males (male: b = 0.026, p =.002), and genetically regulated transcriptomic changes highlighted the effect of SHISHA9 , TEX26 , and NCOA6. Through a comprehensive assessment of genetic risk for neuroticism and the associated biological processes, this study identified several molecular pathways that can partially explain the known sex differences in neurotic symptoms and their psychiatric comorbidities. [ABSTRACT FROM AUTHOR]

• Well-supported cognitively unimpaired plasma NfL reference intervals were determined. • Observed 97.5th percentile NfL concentrations increased at a rate of 3.1% per year of age. • Decade-wide reference intervals will aid in the evaluation of potential neurodegeneration. Neurofilament light chain (NfL) is an emerging biomarker of neurodegenerative disease progression. As plasma NfL increases with age, characterization of NfL concentrations in an age-stratified cognitively unimpaired population was assessed. EDTA-plasma samples were measured using the Simoa® NF-light™ Advantage Kit assay. One-sided reference intervals were established from 1100 cognitive normal individuals (588 male, 512 female) aged 20 to 95 years. Of those, 927 samples were obtained from the Mayo Clinic Study of Aging cohort (age > 50 years), and the remainder (age < 50 years) were obtained from individuals without known neurological conditions. All samples were from individuals without known chronic kidney disease, stroke or myocardial infarction, and a body mass index < 30 kg/m2. The 97.5th percentile limits for the following age ranges (in years) were (pg/mL): 20 s: ≤8.4, 30 s: ≤11.4, 40 s: ≤15.4, 50 s: ≤20.8, 60 s: ≤28.0, 70 s: ≤37.9, 80+: ≤51.2. Sex had no significant effect on reference intervals. Observed NfL concentrations increased at a rate of 3.1 % per year of age. Characterization of the rate of NfL concentration increase and decade-wide reference intervals from a neurologically well-characterized patient population will aid in interpretation of NfL during the clinical evaluation of a potential neurodegenerative disease. [ABSTRACT FROM AUTHOR]

The article focuses on tail loss as the most common predator-induced injury among Thamnophis couchii, T. hammondii, and T. sirtalis, with comparisons to lizards known for caudal autotomy, highlighting the lack of sophisticated traits associated with true caudal autotomy in snakes.

Coevolution has the potential to alter not only the ecological interactions of coevolving partners, but also their interactions with yet other species. The effects of coevolution may ripple throughout networks of interacting species, cascading across trophic levels, swamping competitors, or facilitating survival or reproduction of yet other species linked only indirectly to the coevolving partners. These ripple effects of coevolution may differ among communities, amplifying how the coevolutionary process produces geographic mosaics of traits and outcomes in interactions among species. In a From the Cover article in this issue of Molecular Ecology, Hague et al. (2022) provide a clear example, using the well‐studied interactions between Pacific newts (Taricha spp.) and their common garter snake (Thamnophis sirtalis) predators in western North America. Pacific newts harbour tetrodotoxin (TTX), which is highly toxic to vertebrate predators. In coevolutionary hotspots, extreme escalation of toxicity in the newts and resistance to toxicity in the snakes have resulted in snake populations that retain high levels of TTX. In two geographic regions, snakes in these hotspot populations have evolved bright, aposematic colours that may act as warning signals to their own vertebrate predators. The warning signals and toxin‐resistance alleles in the snake populations decrease clinally away from the coevolutionary hotpots, shaped by a geographically variable mix of selection imposed by the snakes' prey and by their own predators. [ABSTRACT FROM AUTHOR]

For instance, being anchored to specific habitat features that are essential for survival (eg winter shelters for temperate species) likely renders snakes reluctant to disperse long distances and thus unable to effectively respond to habitat loss and changing climate regimes (Deutsch I et al i . For example, intra- or interspecific transmission of the fungal pathogen causing ophidiomycosis, an emerging snake-specific disease afflicting numerous species, may occur in shared winter shelters (Tetzlaff I et al i . In addition to these direct impacts, indirect effects due to communal hyperfidelity may negatively affect snake populations. [Extracted from the article]

Giardia intestinalis is a major diarrhea-causing parasite that colonizes the proximal small intestine of humans and various other mammalian species, including pets and livestock. Despite its global occurrence, there is limited information about the epidemiology of Giardia in reptiles, particularly snakes. The aim of this study was to amplify the beta-giardin (bg) gene of Giardia by polymerase chain reaction (PCR), followed by a comparative evolutionary tree analysis to determine the occurrence and molecular characterization of Giardia in snakes. We collected 603 asymptomatic samples from 26 provinces in China, representing species such as Pantherophis guttatus , Pantherophis obsoletus , Pituophis melanoleucus , Thamnophis sirtalis , Lampropeltis getula , and Heterodon nasicus. Ultimately, a occurrence of Giardia infection of 4.15 % was detected in these snakes, with corn snakes (Pantherophis guttatus) having a significantly higher occurrence than other species. Molecular analysis identified assemblage F as the predominant genotype, and also identified an assemblage B that can infect humans and a variety of mammals. The results of this study illustrate the potential risk of transmission of Giardia from snakes to humans, especially in environments where close contact occurs. The present epidemiological study examines epidemiological investigations of Giardia in reptiles, provides data to understand the zoonotic risk of Giardia , and emphasizes the need for targeted surveillance, stringent hygiene measures, and public awareness campaigns to reduce these risks. • This study is the first large-scale investigation of Giardia in snakes in China. • There were slight impacts on the infection rates of Giardia spp. in sex, species, age, and living conditions. • Odds ratios analysis revealed that the Corn snake exhibited a significantly higher risk of Giardia spp. infection. [ABSTRACT FROM AUTHOR]

As global temperatures continue to rise, understanding the impacts of warming environments has become increasingly important. Temperature is especially relevant for ectothermic organisms which depend upon consistent and predictable annual temperature cycles for reproduction and development. However, additional research is required in this area to elucidate the potential impacts of climate change on future generations. To understand how projected increases in environmental temperatures may impact reproductive outcomes within natural populations of ectothermic vertebrates, we manipulated minimum ambient temperatures during gestation in Red-sided garter snakes (Thamnophis sirtalis parietalis). Wild snakes were collected in the Interlake region of Manitoba, Canada during their spring mating season and allowed to mate in controlled conditions. For the duration of gestation, mated females were placed into one of two ambient thermal conditions: temperatures emulating those found in the species' natural habitat or temperatures with a consistent 5 °C increase to match end-of-century climate change projections. We recorded observations for each litter and all neonates resulting from controlled mating trials. We observed no difference in litter sizes or birth rates between thermal conditions. However, we observed a significant reduction in gestation length and significant increase to neonate body mass and body condition associated with increased ambient temperatures. These results suggest that increased minimum temperatures during gestation may confer reproductive benefits for the northern populations of this species even under the most extreme current modeled warming predictions. We discuss the broader implications of this effect, including possible negative ecological outcomes. • Model climate warming scenarios lead to improved reproductive outcome in snakes. • Improved neonate body condition with no cost to litter size under model conditions. • Significantly reduced gestation period under model conditions. • Broader ecological implications discussed. [ABSTRACT FROM AUTHOR]

The repeated evolution of tetrodotoxin (TTX) resistance provides a model for testing hypotheses about the mechanisms of convergent evolution. This poison is broadly employed as a potent antipredator defence, blocking voltage‐gated sodium channels (Nav) in muscles and nerves, paralysing and sometimes killing predators. Resistance in taxa bearing this neurotoxin and a few predators appears to come from convergent replacements in specific Nav residues that interact with TTX. This stereotyped genetic response suggests molecular and phenotypic evolution may be constrained and predictable. Here, we investigate the extent of mechanistic convergence in garter snakes (Thamnophis) that prey on TTX‐bearing newts (Taricha) by examining the physiological and genetic basis of TTX resistance in the Sierra garter snake (Th. couchii). We characterize variation in this predatory adaptation across populations at several biological scales: whole‐animal TTX resistance; skeletal muscle resistance; functional genetic variation in three Nav encoding loci; and levels of gene expression for one of these loci. We found Th. couchii possess extensive geographical variation in resistance at the whole‐animal and skeletal muscle levels. As in other Thamnophis, resistance at both levels is highly correlated, suggesting convergence across the biological levels linking organism to organ. However, Th. couchii shows no functional variation in Nav loci among populations or difference in candidate gene expression. Local variation in TTX resistance in Th. couchii cannot be explained by the same relationship between genotype and phenotype seen in other taxa. Thus, historical contingencies may lead different species of Thamnophis down alternative routes to local adaptation. [ABSTRACT FROM AUTHOR]

An animal's ability to respond optimally to changing environmental conditions is paramount to successfully reproducing and thus maximizing fitness. Studies on photoperiod-induced changes in neural thyroid hormone metabolism have conclusively linked environmental cues to the neuroendocrine reproductive axis of birds and mammals. Whether this conserved mechanism also transduces changes in environmental temperature, however, has not been fully addressed. We investigated whether the hormone melatonin mediates the effects of low-temperature dormancy on thyroid hormone metabolism within the hypothalamus of red-sided garter snakes (Thamnophis sirtalis parietalis). To address this question, we used immunohistochemistry to assess changes in thyroid-stimulating hormone (TSH) in the infundibulum of the pituitary and deiodinase 3 (Dio3) and gonadotropin-releasing hormone (GnRH) in the hypothalamus. We also asked if changes in TSH, Dio3, and/or GnRH immunoreactivity are associated with changes in male courtship behavior. In contrast to our predictions, 6 weeks of dormancy at 4°C significantly decreased the number of TSH-labeled cells in the infundibulum. It is possible that the observed decrease in TSH is related to the release of snakes from temperature refractoriness, but this idea needs further testing. Treatment of snakes with the melatonin precursor 5-hydroxytryptophan during dormancy at 4°C both reversed the temperature-induced change in TSH immunoreactivity and disrupted the temporal pattern of male courtship behavior. These results suggest that TSH cells within the infundibulum are both modulated by temperature and sensitive to changes in melatonin. As predicted, male snakes hibernated at an elevated temperature of 12°C for 6 weeks and treated with vehicle showed no change in TSH-, Dio3-, or GnRH-immunoreactive cell number. Treatment of snakes with the melatonin receptor antagonist luzindole was not sufficient in rescuing the effects of dormancy at 12°C on TSH immunoreactivity or courtship behavior. However, luzindole-treated snakes showed a significant increase in GnRH-immunoreactive cell number, suggesting that melatonin exerts an inhibitory effect on GnRH in garter snakes. In summary, our results provide critical insights into the mechanisms that mediate the effects of temperature on reproductive physiology and behavior. [ABSTRACT FROM AUTHOR]

Trait specialization often comes at the expense of original trait function, potentially causing evolutionary tradeoffs that may render specialist populations vulnerable to extinction. However, many specialized adaptations evolve repeatedly, suggesting selection favors specialization in specific environments. Some garter snake (Thamnophis) populations possess specialized mutations in voltage‐gated sodium channels that allow them to consume Pacific newts (Taricha) defended by a highly potent neurotoxin (tetrodotoxin). These mutations, however, also decrease protein and muscle function, suggesting garter snakes may suffer evolutionary tradeoffs. We measured a key physiological process, standard metabolic rate (SMR), to investigate whether specialized adaptations in toxin‐resistant garter snakes affect baseline energy expenditure. In snakes, skeletal muscles influence metabolism and power ventilation, so inefficiencies of sodium channels in these muscles might impact whole‐animal energy expenditure. Further, because sodium channels are membrane‐bound proteins, inefficiencies of channel kinetics and performance might be exacerbated at suboptimal temperatures. We measured SMR in 2 species, Thamnophis atratus and Thamnophis sirtalis, that independently evolved tetrodotoxin resistance through unique mutations, providing replicate experiments with distinct underlying genetics and potential physiological costs. Despite our expectations, neither resistance phenotype nor sodium channel genotype affected metabolism and resistant snakes did not perform worse under suboptimal body temperature. Instead, T. atratus and T. sirtalis show nearly identical rates of mass‐adjusted energy expenditure at both temperatures, despite differing eco‐morphologies, life histories, and distant phylogenetic positions. These findings suggest SMR may be a conserved feature of Thamnophis, and that any organismal tradeoffs may be compensated to retain whole‐animal function. [ABSTRACT FROM AUTHOR]

Two adult orange-striped ribbonsnakes, Thamnophis proximus proximus, were collected from northern Arkansas and examined for helminths. A single snake harbored 4 specimens of the pentastomid, Kiricephalus coarctatus. We document a new host as well as a new distributional record for the parasite. This is only the second time a species of pentastomid has been reported from the state in any host. A summary of ophidian hosts of K. coarctatus from the Western Hemisphere is included. [ABSTRACT FROM AUTHOR]