Ontogenetic and geographic venom variation in the Great Basin Rattlesnake, Crotalus oreganus lutosus

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  Ontogenetic and geographic venom variation in the Great Basin Rattlesnake, Crotalus oreganus lutosus Abstract Venom composition among the species of the Western Rattlesnake clade is often quite variable, depending on several factors such as geographic location and ontogeny. Venom composition not only affects the ability of a snake to acquire prey efficiently, but it can also significantly impact snakebite symptomology. Currently, there has been limited characterization of the venom from the Great Basin Rattlesnake ( Crotalus oreganus lutosus ), a lineage that is broadly distributed in the intermontane western United States. In this study we sample 67 individual Great Basin Rattlesnakes collected in Idaho, Utah, California, and Arizona. We find evidence for substantial ontogenetic and geographic variation in venom composition. Of the six toxin families assessed, all showed ontogenetic shifts to varying extents, with some trends differing from those observed in other rattlesnake sp...

Neglected no longer: Phylogenomic resolution of higher-level relationships in Solifugae

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Neglected no longer: Phylogenomic resolution of higher-level relationships in Solifugae

Summary
Advanced sequencing technologies have expedited resolving higher-level arthropod relationships. Yet, dark branches persist, principally among groups occurring in cryptic habitats. Among chelicerates, Solifugae (“camel spiders”) is the last order lacking a higher-level phylogeny and thus, historically characterized as “neglected [arachnid] cousins”. Though renowned for aggression, remarkable running speed, and xeric adaptation, inferring solifuge relationships has been hindered by inaccessibility of diagnostic morphological characters, whereas molecular investigations have been limited to one of 12 recognized families. Our phylogenomic dataset via capture of ultraconserved elements sampling all extant families recovered a well-resolved phylogeny, with two distinct groups of New World taxa nested within a broader Paleotropical radiation. Divergence times using fossil calibrations inferred Solifugae radiated by the Permian, and most families diverged pre-Paleogene-Cretaceous extinction, largely driven by continental breakup. We establish Boreosolifugae new suborder uniting five Laurasian families, and Australosolifugae new suborder uniting seven Gondwanan families using morphological and biogeographic signal.

Siddharth S. Kulkarni,Hugh G. Steiner,Erika L. Garcia,Hernán Iuri,R. Ryan Jones,Jesús A. Ballesteros,Guilherme Gainett,Matthew R. Graham,Danilo Harms,Robin Lyle,Andrés A. Ojanguren-Affilastro,Carlos E. Santibañez-López,Gustavo Silva de Miranda et al.

Publication: 

iScience (PDF)

Publisher: 

Elsevier

Date: 

Available online 19 August 2023