Broad-Scale Climatic Gradients Drive Multiple Facets of Scorpion Beta Diversity in Northeastern Brazil

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  Broad-Scale Climatic Gradients Drive Multiple Facets of Scorpion Beta Diversity in Northeastern Brazil ABSTRACT Aim Beta diversity analyses clarify mechanisms structuring ecological communities, but their multidimensional facets remain poorly explored in arthropods. Here, we quantified taxonomic, phylogenetic, and functional beta diversity in scorpions, partitioned these facets into species replacement and richness differences, and evaluated the relative importance of spatial structure and environmental conditions in driving community assembly. Location Northeastern Brazil, South America. Taxon Scorpions (Arachnida: Scorpiones). Methods Taxonomic beta diversity was estimated using species presence across 70 sites in northeastern Brazil. Phylogenetic turnover was calculated from a multi-locus molecular tree, and functional beta diversity was derived from morphometric and ecological traits. All beta diversity facets were decomposed into replacement and richness-difference component...

The Halloween gene shadow is involved in embryonic development and postembryonic molting in the spider Parasteatoda tepidariorum

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The Halloween gene shadow is involved in embryonic development and postembryonic molting in the spider Parasteatoda tepidariorum

Abstract

Ecdysteroids are key hormones that regulate molting and developmental processes in arthropods, including insect metamorphosis. Understanding the molecular roles of the genes involved in ecdysteroid biosynthesis could provide crucial insights into the evolutionary conservation of regulation and regulatory modifications in arthropods. While extensively studied in insects, the functions of the so-called Halloween genes, encoding enzymes responsible for the conversion of cholesterol to ecdysone and 20-hydroxyecdysone, remain unclear in arachnids. Therefore, this study aims to elucidate the functions of the Halloween gene shadow (Pt-sad) in the spider Parasteatoda tepidariorum in both embryonic and postembryonic stages and to assess its potential role in molting. In situ hybridization was employed to characterize the expression patterns of Pt-sad, and RNAi-mediated knockdown (RNA interference) was conducted to explore its effects on development and molting. Knockdown of Pt-sad resulted in increased embryonic mortality and developmental delays, while it disrupted molt cycles in the postembryonic stages, supporting a role in ecdysteroidogenesis. Expression analysis revealed Pt-sad activity in specific regions of embryos and juveniles, including the central nervous system, appendages, and circulatory system. These findings highlight the multifunctionality of shadow in the spider. While the involvement of this gene in the ecdysteroid pathway is most likely conserved in arthropods, this role may have diversified in spiders to include additional, unique functions that differ from their insect counterparts.
Klinkenbuß, D., Treffkorn, S., Mayer, G., & Prpic, N. (2026). The Halloween gene shadow is involved in embryonic development and postembryonic molting in the spider Parasteatoda tepidariorum. Developmental Biology. https://doi.org/10.1016/j.ydbio.2026.02.010