hesperus tends to be locally abundant and occupies the same microsites as both lizard species (e.g. hesperus in captivity (CRF and VLT 2015, 2017, personal observation). Similarly, diet studies on the western fence lizard ( Sceloporus occidentalis) suggest they regularly consume spiders, and we have observed S. Southern alligator lizards ( Elgaria multicarinata) are known to consume dangerous western black widow spiders ( Latrodectus hesperus) and even seek out their toxic egg sacs. We describe a previously unexplored system involving potential spider venom resistance in sympatric lizard predators. Thus, it remains unknown whether lizards have evolved specialized adaptations to tolerate or overcome the venom of their spider prey. Surprisingly, little work has focused on adaptations that might facilitate the predator–prey relationship between lizards and spiders, which is probably chemically mediated (via spider venom). However, this relationship is not unidirectional, as most spiders are armed with venom and some are major predators of small vertebrates including lizards. In fact, lizards appear to be particularly important predators of arachnids, regulating the abundance, richness and diversity of spiders in certain communities. Lizards are a diverse and widespread group of reptiles that are important consumers of arthropods. Here, we test the notion that ecological interactions between venomous spider prey and their lizard predators have led to the evolution of adaptive venom resistance in lizards. Lizards and spiders represent natural adversaries that have been long overlooked. Despite these remarkable examples, we still know little about adaptive toxin resistance in most predator–prey systems. Examples include pit viper venom resistance in squirrel and opossum prey, scorpion venom resistance in grasshopper mice predators, resistance to toad poisons in predatory snakes and lizards and resistance to newt neurotoxins in garter snake predators.

Given the right ecological and evolutionary conditions, physiological resistance towards toxins may then evolve, as seen across diverse predator–prey systems. poison or venom) they face from their ecological partner. In many predator–prey systems, ecological interactions are chemically mediated requiring one or both natural enemies to avoid or mitigate the toxins (i.e. Our data suggest predator–prey relationships between lizards and spiders are complex, possibly leading to physiological and molecular adaptations that allow some lizards to tolerate or overcome the dangerous defences of their arachnid prey.Īntagonistic relationships, such as those between predator and prey, can have life and death outcomes, thereby exerting intense selective pressures on the species involved. stansburiana exhibited increased muscle damage and immune system infiltration in response to BWSV. multicarinata showed minimal tissue damage and immune response, while S. stansburiana suffered significant performance reductions in response to BWSV. Sprint speed was not significantly decreased in E.

We investigated BWSV effects on whole-animal performance (sprint) and muscle tissue at two venom doses compared with control injections. We evaluated potential resistance to BWSV in the lizards that consume black widows, and a potentially susceptible species ( Uta stansburiana) known as prey of widows. The consequences of black widow spider venom (BWSV) can be severe, and are well understood for mammals but unknown for reptiles. In the Western USA, two lizard species ( Elgaria multicarinata and Sceloporus occidentalis) are sympatric with and predate western black widow spiders ( Latrodectus hesperus). Lizards and spiders are natural adversaries, yet little is known of adaptations that lizards might possess for dealing with the venomous defences of spider prey.

Redback spider predators