Thamnophis sirtalis and their toxic relationship: Testing for intraspecific venom variation in Common Garter Snakes.

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.

Where the "ruber" Meets the Road: Using the Genome of the Red Diamond Rattlesnake to Unravel the Evolutionary Processes Driving Venom Evolution.

Understanding the proximate and ultimate causes of phenotypic variation is fundamental in evolutionary research, as such variation provides the substrate for selection to act upon. Although trait variation can arise due to selection, the importance of neutral processes is sometimes understudied. We presented the first reference-quality genome of the Red Diamond Rattlesnake (Crotalus ruber) and used range-wide 'omic data to estimate the degree to which neutral and adaptive evolutionary processes shaped venom evolution.

Sequence Divergence in Venom Genes Within and Between Montane Pitviper (Viperidae: Crotalinae: Cerrophidion) Species is Driven by Mutation-Drift Equilibrium.

Snake venom can vary both among and within species. While some groups of New World pitvipers-such as rattlesnakes-have been well studied, very little is known about the venom of montane pitvipers (Cerrophidion) found across the Mesoamerican highlands. Compared to most well-studied rattlesnakes, which are widely distributed, the isolated montane populations of Cerrophidion may facilitate unique evolutionary trajectories and venom differentiation.

Venom phenotype conservation suggests integrated specialization in a lizard-eating snake.

Biological specialization reduces the size of niche space while increasing efficiency in the use of available resources. Specialization often leads to phenotypic changes via natural selection aligning with niche space constraints. Commonly observed changes are in size, shape, behavior, and traits associated with feeding.

Evolutionary allometry and ecological correlates of fang length evolution in vipers.

Traits for prey acquisition form the phenotypic interface of predator-prey interactions. In venomous predators, morphological variation in venom delivery apparatus like fangs and stingers may be optimized for dispatching prey. Here, we determine how a single dimension of venom injection systems evolves in response to variation in the size, climatic conditions and dietary ecology of viperid snakes.

De Novo Genome Assembly Highlights the Role of Lineage-Specific Gene Duplications in the Evolution of Venom in Fea's Viper (Azemiops feae).

Despite the medical significance to humans and important ecological roles filled by vipers, few high-quality genomic resources exist for these snakes outside of a few genera of pitvipers. Here we sequence, assemble, and annotate the genome of Fea's Viper (Azemiops feae). This taxon is distributed in East Asia and belongs to a monotypic subfamily, sister to the pitvipers.

Characterization of the venom and external morphology of a natural hybrid between Crotalus atrox and Crotalus mictlantecuhtli.

Here we report, for the first time, a natural hybrid between Crotalus atrox and C. mictlantecuhtli based on intermediate characteristics of the external morphology and venom. Morphologically, the individual had characteristics of both parent species.

Duvernoy's Gland Transcriptomics of the Plains Black-Headed Snake, (Squamata, Colubridae): Unearthing the Venom of Small Rear-Fanged Snakes.

The venoms of small rear-fanged snakes (RFS) remain largely unexplored, despite increased recognition of their importance in understanding venom evolution more broadly. Sequencing the transcriptome of venom-producing glands has greatly increased the ability of researchers to examine and characterize the toxin repertoire of small taxa with low venom yields. Here, we use RNA-seq to characterize the Duvernoy's gland transcriptome of the Plains Black-headed Snake, , a small, semi-fossorial colubrid that feeds on a variety of potentially dangerous arthropods including centipedes and spiders.

Phylogenetically diverse diets favor more complex venoms in North American pitvipers.

The role of natural selection in the evolution of trait complexity can be characterized by testing hypothesized links between complex forms and their functions across species. Predatory venoms are composed of multiple proteins that collectively function to incapacitate prey. Venom complexity fluctuates over evolutionary timescales, with apparent increases and decreases in complexity, and yet the causes of this variation are unclear.

Protein composition and biochemical characterization of venom from Sonoran Coral Snakes (Micruroides euryxanthus).

The elapid genus, Micruroides, is considered the sister clade of all New World coral snakes (Genus Micrurus), is monotypic, and is represented by Sonoran Coral Snakes, Micruroides euryxanthus. Coral snakes of the genus Micrurus have been reported to have venoms that are predominantly composed of phospholipases A (PLA) or three finger toxins (3FTx), but the venoms of the genus Micruroides are almost completely unstudied. Here, we present the first description of the venom of M.

The Tiger Rattlesnake genome reveals a complex genotype underlying a simple venom phenotype.

Variation in gene regulation is ubiquitous, yet identifying the mechanisms producing such variation, especially for complex traits, is challenging. Snake venoms provide a model system for studying the phenotypic impacts of regulatory variation in complex traits because of their genetic tractability. Here, we sequence the genome of the Tiger Rattlesnake, which possesses the simplest and most toxic venom of any rattlesnake species, to determine whether the simple venom phenotype is the result of a simple genotype through gene loss or a complex genotype mediated through regulatory mechanisms.

Genomic Adaptations to Salinity Resist Gene Flow in the Evolution of Floridian Watersnakes.

The migration-selection balance often governs the evolution of lineages, and speciation with gene flow is now considered common across the tree of life. Ecological speciation is a process that can facilitate divergence despite gene flow due to strong selective pressures caused by ecological differences; however, the exact traits under selection are often unknown. The transition from freshwater to saltwater habitats provides strong selection targeting traits with osmoregulatory function.

Neutralizing potency and immunochemical evaluation of an anti-Crotalus mictlantecuhtli experimental serum.

Snakebite in Mexico is commonly treated with an antivenom which uses Bothrops asper and Crotalus simus venoms as immunogens. Current taxonomic recommendations for the C. simus species complex suggest a novel endemic species from Mexico: Crotalus mictlantecuhtli.

Trait differentiation and modular toxin expression in palm-pitvipers.

Background: Modularity is the tendency for systems to organize into semi-independent units and can be a key to the evolution and diversification of complex biological systems. Snake venoms are highly variable modular systems that exhibit extreme diversification even across very short time scales. One well-studied venom phenotype dichotomy is a trade-off between neurotoxicity versus hemotoxicity that occurs through the high expression of a heterodimeric neurotoxic phospholipase A (PLA) or snake venom metalloproteinases (SVMPs).

Intraspecific sequence and gene expression variation contribute little to venom diversity in sidewinder rattlesnakes ( Crotalus cerastes).

Traits can evolve rapidly through changes in gene expression or protein-coding sequences. However, these forms of genetic variation can be correlated and changes to one can influence the other. As a result, we might expect traits lacking differential expression to preferentially evolve through changes in protein sequences or morphological adaptation.

Evidence for divergent patterns of local selection driving venom variation in Mojave Rattlesnakes (Crotalus scutulatus).

Snake venoms represent an enriched system for investigating the evolutionary processes that lead to complex and dynamic trophic adaptations. It has long been hypothesized that natural selection may drive geographic variation in venom composition, yet previous studies have lacked the population genetic context to examine these patterns. We leverage range-wide sampling of Mojave Rattlesnakes (Crotalus scutulatus) and use a combination of venom, morphological, phylogenetic, population genetic, and environmental data to characterize the striking dichotomy of neurotoxic (Type A) and hemorrhagic (Type B) venoms throughout the range of this species.

Ontogenetic Change in the Venom of Mexican Black-Tailed Rattlesnakes ().

Ontogenetic changes in venom composition have important ecological implications due the relevance of venom in prey acquisition and defense. Additionally, intraspecific venom variation has direct medical consequences for the treatment of snakebite. However, ontogenetic changes are not well documented in most species.

Comparative venom-gland transcriptomics and venom proteomics of four Sidewinder Rattlesnake (Crotalus cerastes) lineages reveal little differential expression despite individual variation.

Changes in gene expression can rapidly influence adaptive traits in the early stages of lineage diversification. Venom is an adaptive trait comprised of numerous toxins used for prey capture and defense. Snake venoms can vary widely between conspecific populations, but the influence of lineage diversification on such compositional differences are unknown.

Venom characterization of the three species of Ophryacus and proteomic profiling of O. sphenophrys unveils Sphenotoxin, a novel Crotoxin-like heterodimeric β-neurotoxin.

Venoms of the three species of Ophryacus (O. sphenophrys, O. smaragdinus, and O.

Hidden diversity within the depauperate genera of the snake tribe Lampropeltini (Serpentes, Colubridae).

Accurate representation of lineage diversity through complete taxon sampling is crucial to understanding the evolution of biodiversity, particularly when using molecular phylogenetics to estimate evolutionary relationships. In this interest, taxonomic diversity is often used as a proxy for lineage diversity even though the two concepts are not synonymous. We explore this within the snake tribe Lampropeltini which includes some of the most conspicuous and heavily studied snakes in North America.

Cryptic genetic diversity, population structure, and gene flow in the Mojave rattlesnake (Crotalus scutulatus).

The Mojave rattlesnake (Crotalus scutulatus) inhabits deserts and arid grasslands of the western United States and Mexico. Despite considerable interest in its highly toxic venom and the recognition of two subspecies, no molecular studies have characterized range-wide genetic diversity and population structure or tested species limits within C. scutulatus.

Phenotypic Variation in Mojave Rattlesnake (Crotalus scutulatus) Venom Is Driven by Four Toxin Families.

Phenotypic diversity generated through altered gene expression is a primary mechanism facilitating evolutionary response in natural systems. By linking the phenotype to genotype through transcriptomics, it is possible to determine what changes are occurring at the molecular level. High phenotypic diversity has been documented in rattlesnake venom, which is under strong selection due to its role in prey acquisition and defense.