Guatemalan beaded lizards (Helodermatidae: Heloderma charlesbogerti) navigate and follow a scent trail in maze tasks.

Maze studies have provided substantial information about nonhuman cognition, such as insights on navigational strategies, spatial memory, and choice discriminations. This knowledge can aid in how we understand the foraging strategies of many animals, particularly understudied and endangered species, such as the Guatemalan beaded lizard (Heloderma charlesbogerti). These actively foraging lizards rely on chemoreception to locate prey, but it is unknown to what extent they engage in olfaction and vomerolfaction to hunt and navigate their environment. We investigated how Guatemalan beaded lizards moved through a physical maze. When navigating an eight-arm radial maze with all arms baited, lizards tended to turn into the immediately adjacent arm in a single direction, similar to other reptiles that have been tested in radial arm mazes. In a T-maze, the lizards had to discriminate between arms that contained scent and no-scent from a distance. They were generally unable to choose the baited (correct) arm at levels greater than chance, indicating an inability for this discrimination. With the addition of a scent trail, however, all lizards chose the baited arm at levels significantly above chance, and this increased accuracy was correlated with increased latency to make the arm choice. The lizards also demonstrated a decreased rate of tongue flicking as proximity to reward increased. Guatemalan beaded lizards can efficiently navigate a radial arm maze and can successfully use vomerolfaction with substrate-borne cues to locate prey, but they appear to have minimal olfaction abilities when sensing from a distance. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Conservation tools: the next generation of engineering-biology collaborations.

The recent increase in public and academic interest in preserving biodiversity has led to the growth of the field of conservation technology. This field involves designing and constructing tools that use technology to aid in the conservation of wildlife. In this review, we present five case studies and infer a framework for designing conservation tools (CT) based on human-wildlife interaction. Successful CT range in complexity from cat collars to machine learning and game theory methodologies and do not require technological expertise to contribute to conservation tool creation. Our goal is to introduce researchers to the field of conservation technology and provide references for guiding the next generation of conservation technologists. Conservation technology not only has the potential to benefit biodiversity but also has broader impacts on fields such as sustainability and environmental protection. By using innovative technologies to address conservation challenges, we can find more effective and efficient solutions to protect and preserve our planet's resources.

A Guide for Successful Research Collaborations between Zoos and Universities.

Zoos offer university researchers unique opportunities to study animals that would be difficult or impractical to find in the wild. However, the different cultures, goals, and priorities of these institutions can be a source of conflict. How can researchers build mutually beneficial collaborations with their local zoo? In this article, we present the results of a survey of 117 personnel from 59 zoos around the United States, where we highlight best practices spanning all phases of collaboration, from planning to working alongside the zoo and maintaining contact afterward. Collaborations were not possible if university personnel did not appreciate the zoo staff's time constraints as well as the differences between zoo animals and laboratory animals. We include a vision for how to improve zoo collaborations, along with a history of our own decade-long collaborations with Zoo Atlanta. A central theme is the long-term establishment of trust between institutions.

Bridging the Research Gap between Live Collections in Zoos and Preserved Collections in Natural History Museums.

Zoos and natural history museums are both collections-based institutions with important missions in biodiversity research and education. Animals in zoos are a repository and living record of the world's biodiversity, whereas natural history museums are a permanent historical record of snapshots of biodiversity in time. Surprisingly, despite significant overlap in institutional missions, formal partnerships between these institution types are infrequent. Life history information, pedigrees, and medical records maintained at zoos should be seen as complementary to historical records of morphology, genetics, and distribution kept at museums. Through examining both institution types, we synthesize the benefits and challenges of cross-institutional exchanges and propose actions to increase the dialog between zoos and museums. With a growing recognition of the importance of collections to the advancement of scientific research and discovery, a transformational impact could be made with long-term investments in connecting the institutions that are caretakers of living and preserved animals.

Functional consequences of convergently evolved microscopic skin features on snake locomotion.

The small structures that decorate biological surfaces can significantly affect behavior, yet the diversity of animal-environment interactions essential for survival makes ascribing functions to structures challenging. Microscopic skin textures may be particularly important for snakes and other limbless locomotors, where substrate interactions are mediated solely through body contact. While previous studies have characterized ventral surface features of some snake species, the functional consequences of these textures are not fully understood. Here, we perform a comparative study, combining atomic force microscopy measurements with mathematical modeling to generate predictions that link microscopic textures to locomotor performance. We discover an evolutionary convergence in the ventral skin structures of a few sidewinding specialist vipers that inhabit sandy deserts-an isotropic texture that is distinct from the head-to-tail-oriented, micrometer-sized spikes observed on a phylogenetically broad sampling of nonsidewinding vipers and other snakes from diverse habitats and wide geographic range. A mathematical model that relates structural directionality to frictional anisotropy reveals that isotropy enhances movement during sidewinding, whereas anisotropy improves movement during slithering via lateral undulation of the body. Our results highlight how an integrated approach can provide quantitative predictions for structure-function relationships and insights into behavioral and evolutionary adaptations in biological systems.

Side-impact collision: mechanics of obstacle negotiation in sidewinding snakes.

Snakes excel at moving through cluttered environments, and heterogeneities can be used as propulsive contacts for snakes performing lateral undulation. However, sidewinding, which is often associated with sandy deserts, cuts a broad path through its environment that may increase its vulnerability to obstacles. Our prior work demonstrated that sidewinding can be represented as a pair of orthogonal body waves (vertical and horizontal) that can be independently modulated to achieve high maneuverability and incline ascent, suggesting that sidewinders may also use template modulations to negotiate obstacles. To test this hypothesis, we recorded overhead video of four sidewinder rattlesnakes (Crotalus cerastes) crossing a line of vertical pegs placed in the substrate. Snakes used three methods to traverse the obstacles: a Propagate Through behavior in which the lifted moving portion of the snake was deformed around the peg and dragged through as the snake continued sidewinding (115/160 runs), Reversal turns that reorient the snake entirely (35/160), or switching to Concertina locomotion (10/160). The Propagate Through response was only used if the anterior-most region of static contact would propagate along a path anterior to the peg, or if a new region of static contact could be formed near the head to satisfy this condition; otherwise, snakes could only use Reversal turns or switch to Concertina locomotion. Reversal turns allowed the snake to re-orient and either escape without further peg contact or re-orient into a posture amenable to using the Propagate Through response. We developed an algorithm to reproduce the Propagate Through behavior in a robophysical model using a modulation of the two-wave template. This range of behavioral strategies provides sidewinders with a versatile range of options for effectively negotiating obstacles in their natural habitat, as well as provide insights into the design and control of robotic systems dealing with heterogeneous habitats.

Surprising simplicities and syntheses in limbless self-propulsion in sand.

Animals moving on and in fluids and solids move their bodies in diverse ways to generate propulsion and lift forces. In fluids, animals can wiggle, stroke, paddle or slap, whereas on hard frictional terrain, animals largely engage their appendages with the substrate to avoid slip. Granular substrates, such as desert sand, can display complex responses to animal interactions. This complexity has led to locomotor strategies that make use of fluid-like or solid-like features of this substrate, or combinations of the two. Here, we use examples from our work to demonstrate the diverse array of methods used and insights gained in the study of both surface and subsurface limbless locomotion in these habitats. Counterintuitively, these seemingly complex granular environments offer certain experimental, theoretical, robotic and computational advantages for studying terrestrial movement, with the potential for providing broad insights into morphology and locomotor control in fluids and solids, including neuromechanical control templates and morphological and behavioral evolution. In particular, granular media provide an excellent testbed for a locomotion framework called geometric mechanics, which was introduced by particle physicists and control engineers in the last century, and which allows quantitative analysis of alternative locomotor patterns and morphology to test for control templates, optimality and evolutionary alternatives. Thus, we posit that insights gained from movement in granular environments can be translated into principles that have broader applications across taxa, habitats and movement patterns, including those at microscopic scales.

Response to Comment on "Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity".

Lambert et al question our retrospective and holistic epidemiological assessment of the role of chytridiomycosis in amphibian declines. Their alternative assessment is narrow and provides an incomplete evaluation of evidence. Adopting this approach limits understanding of infectious disease impacts and hampers conservation efforts. We reaffirm that our study provides unambiguous evidence that chytridiomycosis has affected at least 501 amphibian species.

Genome of the Komodo dragon reveals adaptations in the cardiovascular and chemosensory systems of monitor lizards.

Monitor lizards are unique among ectothermic reptiles in that they have high aerobic capacity and distinctive cardiovascular physiology resembling that of endothermic mammals. Here, we sequence the genome of the Komodo dragon Varanus komodoensis, the largest extant monitor lizard, and generate a high-resolution de novo chromosome-assigned genome assembly for V. komodoensis using a hybrid approach of long-range sequencing and single-molecule optical mapping. Comparing the genome of V. komodoensis with those of related species, we find evidence of positive selection in pathways related to energy metabolism, cardiovascular homoeostasis, and haemostasis. We also show species-specific expansions of a chemoreceptor gene family related to pheromone and kairomone sensing in V. komodoensis and other lizard lineages. Together, these evolutionary signatures of adaptation reveal the genetic underpinnings of the unique Komodo dragon sensory and cardiovascular systems, and suggest that selective pressure altered haemostasis genes to help Komodo dragons evade the anticoagulant effects of their own saliva. The Komodo dragon genome is an important resource for understanding the biology of monitor lizards and reptiles worldwide.

Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity.

Anthropogenic trade and development have broken down dispersal barriers, facilitating the spread of diseases that threaten Earth's biodiversity. We present a global, quantitative assessment of the amphibian chytridiomycosis panzootic, one of the most impactful examples of disease spread, and demonstrate its role in the decline of at least 501 amphibian species over the past half-century, including 90 presumed extinctions. The effects of chytridiomycosis have been greatest in large-bodied, range-restricted anurans in wet climates in the Americas and Australia. Declines peaked in the 1980s, and only 12% of declined species show signs of recovery, whereas 39% are experiencing ongoing decline. There is risk of further chytridiomycosis outbreaks in new areas. The chytridiomycosis panzootic represents the greatest recorded loss of biodiversity attributable to a disease.

Growth rates of juvenile Boa constrictor under two feeding regimes.

Many husbandry routines in zoo herpetology are based on tradition, authoritarianism, anecdote, or speculation. However, relatively few empirical studies underlie many very common practices. We compared growth rates among littermates of Boa constrictor raised under two feeding regimes that were identical in terms of the mass of food ingested, but differed in weekly versus bi-weekly schedules. The growth rate of the group fed weekly was greater than the rate for the biweekly group. Snakes fed 10% of their body mass on a weekly regimen grew to a larger size, and at a faster rate, than did snakes fed 20% of their body mass on a biweekly regimen.

A taxonomic review of the genus Hemiphractus (Anura: Hemiphractidae) in Panama: Description of Two New Species, Resurrection of Hemiphractus panamensis (Stejneger, 1917), and Discussion of Hemiphractus fasciatus Peters, 1862.

We reviewed the taxonomic status of populations of frogs in the genus Hemiphractus in Panama, which have all been referred to Hemiphractus fasciatus Peters, 1862 for over 40 years. Although relatively few specimens have been collected, mostly juveniles, it is clear that these frogs inhabit three separate upland regions of the country: The Cordillera de Talamanca in western Panama, the Chagres Highlands and Cordillera de San Blas in central Panama, and the Serranía de Pirre in the far eastern portion of the country. In accordance with previously published molecular data, we identified distinctive features of the skulls of frogs representing these three allopatric populations and herein revalidate H. panamensis (Stejneger, 1917), describe the new species Hemiphractus elioti sp. nov. from the Cordillera de Talamanca, and the new species Hemiphractus kaylockae sp. nov. from the Serranía de Pirre. We also propose that the taxon H. fasciatus is a South American species not occurring in Panama.

Genetic diversity and sex ratio of naked mole rat, Heterocephalus glaber, zoo populations.

The naked mole rat, Heterocephalus glaber, is a highly unusual mammal that displays a complex social system similar to that found in eusocial insects. Colonies of H. glaber are commonly maintained in zoo collections because they represent fascinating educational exhibits for the public. However, little is known about the genetic structure or sex ratio of captive populations of H. glaber. In this study, we developed a set of microsatellite markers to examine genetic variation in three captive zoo populations of H. glaber. We also studied sex ratio of these captive populations. Our goal was to determine levels of genetic variation within, and genetic differences between, captive populations of H. glaber. Overall, we found modest levels of genetic variation in zoo populations. We also uncovered little evidence for inbreeding within the captive populations. However, zoo populations did differ genetically, which may reflect the isolation of captive naked mole rat colonies. Finally, we found no evidence of biased sex ratios within colonies. Overall, our study documents levels of genetic variation and sex ratios in a captive eusocial mammalian population. Our results may provide insight into how to manage captive populations of H. glaber.

The Effects of Captivity on the Mammalian Gut Microbiome.

Recent studies increasingly note the effect of captivity or the built environment on the microbiome of humans and other animals. As symbiotic microbes are essential to many aspects of biology (e.g., digestive and immune functions), it is important to understand how lifestyle differences can impact the microbiome, and, consequently, the health of hosts. Animals living in captivity experience a range of changes that may influence the gut bacteria, such as diet changes, treatments, and reduced contact with other individuals, species and variable environmental substrates that act as sources of bacterial diversity. Thus far, initial results from previous studies point to a pattern of decreased bacterial diversity in captive animals. However, these studies are relatively limited in the scope of species that have been examined. Here we present a dataset that includes paired wild and captive samples from mammalian taxa across six Orders to investigate generalizable patterns of the effects captivity on mammalian gut bacteria. In comparing the wild to the captive condition, our results indicate that alpha diversity of the gut bacteria remains consistent in some mammalian hosts (bovids, giraffes, anteaters, and aardvarks), declines in the captive condition in some hosts (canids, primates, and equids), and increases in the captive condition in one host taxon (rhinoceros). Differences in gut bacterial beta diversity between the captive and wild state were observed for most of the taxa surveyed, except the even-toed ungulates (bovids and giraffes). Additionally, beta diversity variation was also strongly influenced by host taxonomic group, diet type, and gut fermentation physiology. Bacterial taxa that demonstrated larger shifts in relative abundance between the captive and wild states included members of the Firmicutes and Bacteroidetes. Overall, the patterns that we observe will inform a range of disciplines from veterinary practice to captive breeding efforts for biological conservation. Furthermore, bacterial taxa that persist in the captive state provide unique insight into symbiotic relationships with the host.

The Oral and Skin Microbiomes of Captive Komodo Dragons Are Significantly Shared with Their Habitat.

Examining the way in which animals, including those in captivity, interact with their environment is extremely important for studying ecological processes and developing sophisticated animal husbandry. Here we use the Komodo dragon (Varanus komodoensis) to quantify the degree of sharing of salivary, skin, and fecal microbiota with their environment in captivity. Both species richness and microbial community composition of most surfaces in the Komodo dragon's environment are similar to the Komodo dragon's salivary and skin microbiota but less similar to the stool-associated microbiota. We additionally compared host-environment microbiome sharing between captive Komodo dragons and their enclosures, humans and pets and their homes, and wild amphibians and their environments. We observed similar host-environment microbiome sharing patterns among humans and their pets and Komodo dragons, with high levels of human/pet- and Komodo dragon-associated microbes on home and enclosure surfaces. In contrast, only small amounts of amphibian-associated microbes were detected in the animals' environments. We suggest that the degree of sharing between the Komodo dragon microbiota and its enclosure surfaces has important implications for animal health. These animals evolved in the context of constant exposure to a complex environmental microbiota, which likely shaped their physiological development; in captivity, these animals will not receive significant exposure to microbes not already in their enclosure, with unknown consequences for their health. IMPORTANCE Animals, including humans, have evolved in the context of exposure to a variety of microbial organisms present in the environment. Only recently have humans, and some animals, begun to spend a significant amount of time in enclosed artificial environments, rather than in the more natural spaces in which most of evolution took place. The consequences of this radical change in lifestyle likely extend to the microbes residing in and on our bodies and may have important implications for health and disease. A full characterization of host-microbe sharing in both closed and open environments will provide crucial information that may enable the improvement of health in humans and in captive animals, both of which experience a greater incidence of disease (including chronic illness) than counterparts living under more ecologically natural conditions.

Conservation threats and the phylogenetic utility of IUCN Red List rankings in Incilius toads.

Phylogenetic analysis of extinction threat is an emerging tool in the field of conservation. However, there are problems with the methods and data as commonly used. Phylogenetic sampling usually extends to the level of family or genus, but International Union for Conservation of Nature (IUCN) rankings are available only for individual species, and, although different species within a taxonomic group may have the same IUCN rank, the species may have been ranked as such for different reasons. Therefore, IUCN rank may not reflect evolutionary history and thus may not be appropriate for use in a phylogenetic context. To be used appropriately, threat-risk data should reflect the cause of extinction threat rather than the IUCN threat ranking. In a case study of the toad genus Incilius, with phylogenetic sampling at the species level (so that the resolution of the phylogeny matches character data from the IUCN Red List), we analyzed causes of decline and IUCN threat rankings by calculating metrics of phylogenetic signal (such as Fritz and Purvis' D). We also analyzed the extent to which cause of decline and threat ranking overlap by calculating phylogenetic correlation between these 2 types of character data. Incilius species varied greatly in both threat ranking and cause of decline; this variability would be lost at a coarser taxonomic resolution. We found far more phylogenetic signal, likely correlated with evolutionary history, for causes of decline than for IUCN threat ranking. Individual causes of decline and IUCN threat rankings were largely uncorrelated on the phylogeny. Our results demonstrate the importance of character selection and taxonomic resolution when extinction threat is analyzed in a phylogenetic context.

A review of the biology and literature of the Gulf Coast Toad (Incilius nebulifer), native to Mexico and the United States.

The Gulf Coast Toad (Incilius nebulifer) is an abundant and widespread species within its range in the United States and Mexico, so it appears on many faunal checklists and is considered in diverse kinds of research. We review the basic biology, distribution, and published history of this species, identifying only those records and publications referable to I. nebulifer, to help researchers identify published works pertaining to I. nebulfer rather than I. valliceps, with which it formerly was considered to be conspecific.

Modulation of orthogonal body waves enables high maneuverability in sidewinding locomotion.

Many organisms move using traveling waves of body undulation, and most work has focused on single-plane undulations in fluids. Less attention has been paid to multiplane undulations, which are particularly important in terrestrial environments where vertical undulations can regulate substrate contact. A seemingly complex mode of snake locomotion, sidewinding, can be described by the superposition of two waves: horizontal and vertical body waves with a phase difference of ± 90°. We demonstrate that the high maneuverability displayed by sidewinder rattlesnakes (Crotalus cerastes) emerges from the animal's ability to independently modulate these waves. Sidewinder rattlesnakes used two distinct turning methods, which we term differential turning (26° change in orientation per wave cycle) and reversal turning (89°). Observations of the snakes suggested that during differential turning the animals imposed an amplitude modulation in the horizontal wave whereas in reversal turning they shifted the phase of the vertical wave by 180°. We tested these mechanisms using a multimodule snake robot as a physical model, successfully generating differential and reversal turning with performance comparable to that of the organisms. Further manipulations of the two-wave system revealed a third turning mode, frequency turning, not observed in biological snakes, which produced large (127°) in-place turns. The two-wave system thus functions as a template (a targeted motor pattern) that enables complex behaviors in a high-degree-of-freedom system to emerge from relatively simple modulations to a basic pattern. Our study reveals the utility of templates in understanding the control of biological movement as well as in developing control schemes for limbless robots.

Locomotor benefits of being a slender and slick sand swimmer.

Squamates classified as 'subarenaceous' possess the ability to move long distances within dry sand; body elongation among sand and soil burrowers has been hypothesized to enhance subsurface performance. Using X-ray imaging, we performed the first kinematic investigation of the subsurface locomotion of the long, slender shovel-nosed snake (Chionactis occipitalis) and compared its biomechanics with those of the shorter, limbed sandfish lizard (Scincus scincus). The sandfish was previously shown to maximize swimming speed and minimize the mechanical cost of transport during burial. Our measurements revealed that the snake also swims through sand by propagating traveling waves down the body, head to tail. Unlike the sandfish, the snake nearly followed its own tracks, thus swimming in an approximate tube of self-fluidized granular media. We measured deviations from tube movement by introducing a parameter, the local slip angle, ßs, which measures the angle between the direction of movement of each segment and body orientation. The average ßs was smaller for the snake than for the sandfish; granular resistive force theory (RFT) revealed that the curvature utilized by each animal optimized its performance. The snake benefits from its slender body shape (and increased vertebral number), which allows propagation of a higher number of optimal curvature body undulations. The snake's low skin friction also increases performance. The agreement between experiment and RFT combined with the relatively simple properties of the granular 'frictional fluid' make subarenaceous swimming an attractive system to study functional morphology and bauplan evolution.