Two new arthropod toxins purified from the venom of the Mexican scorpion Centruroides nigrescens

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  Two new arthropod toxins purified from the venom of the Mexican scorpion Centruroides nigrescens Abstract The venom of the slender black scorpion Centruroides nigrescens , from the State of Guerrero México, was fractionated by Sephadex G–50 gel filtration, followed by carboxymethyl cellulose ion separation and high–performance liquid chromatography, permitting to obtain two new peptides toxic to arthropods. The estimate LD 50 of the soluble venom for the insect Acheta domesticus was 11.1 μg/g body weight, and for the arthropod Armadillidium vulgare was 61.1 μg body weight . The amino acid sequence of toxin Cnige1 (toxic to A. domesticus and A. vulgare ) contains 65 amino acids, with a molecular mass of 7273.37 mass units, whereas toxin Cnige2, toxic to A. domesticus , contains 68 amino acids, with a molecular mass of 7548.81 units. Both peptides are well packed, containing 8 cysteines, which in the native venoms are forming 4 disulfide bridges each. The amino acid sequences f...

Fundamental Niche Conservatism in the Geographic-Range-Expanding Specialist Zodarion rubidum (Zodariidae, Araneae)

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Fundamental Niche Conservatism in the Geographic-Range-Expanding Specialist Zodarion rubidum (Zodariidae, Araneae)

ABSTRACT

Ecological niche and geographic range concepts are essentially interrelated with the latter being conditioned by species' fundamental ecological tolerances, their intrinsic ability to disperse across landscapes, and the various possible interactions between organisms. Despite local fluctuations in range margin areas, geographic ranges are expected to be relatively stable on a broad scale. Range expansion examples therefore provide good opportunities to understand the importance of dispersal in defining species distributions, and to determine whether fundamental niches are conserved or whether species undergo adaptive evolutionary changes during their expansion. In this study, we investigated the spreading tendencies of the specialist spider, Zodarion rubidum Simon, 1914, comparing different phenotypic traits between three localities from southern, central and northern Europe. We conducted four experiments using field-collected and laboratory-reared specimens. We focused on population-specific locomotory traits, temperature preference and inter-molt interval at two temperatures, and venom specificity to investigate the species' dispersal abilities and fundamental thermal and dietary niches. We found no indication of spatial sorting, i.e., no highly dispersive phenotypes in the northern population. Moreover, we found no clear indication of changes in the species thermal biology or in venom specificity over space. Specifically, Z. rubidum showed similar temperature preferences between localities, a slower development under warm temperatures in central and northern European populations (possibly reflecting an adaptive shift toward colder temperatures), and a consistent ability to paralyze phylogenetically distant ant species. Overall, we conclude that Z. rubidum spreading might have been human-mediated and that it does not show major changes in its fundamental niche across space.

Viel, N., T. Bilde, J. G. Sørensen, J. Pétillon, and S. Pekár. 2026. “ Fundamental Niche Conservatism in the Geographic-Range-Expanding Specialist Zodarion rubidum (Zodariidae, Araneae).” Journal of Zoology 1–11. https://doi.org/10.1111/jzo.70165.