Big Spider, Big Genome: Chromosome-level genome of a North American tarantula (Aphonopelma marxi) and comparative genomics across 300 million years of spider evolution

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  Image Credit: WikiCommons Big Spider, Big Genome: Chromosome-level genome of a North American tarantula (Aphonopelma marxi) and comparative genomics across 300 million years of spider evolution Abstract The comparison of chromosome-level genomes allows biologists to investigate new axes of organismal evolution. Spiders comprise a significant proportion of known arachnid diversity, with many complex morphologies and unique natural histories, yet comparative genomics in spiders has been limited due to the number of available genomes. We present a de novo chromosomal reference genome of a mature male tarantula, Aphonopelma marxi, and comparatively examine spider genome evolution across the Order Araneae. Using PacBio HiFi and Hi-C sequencing, the final 6.5 Gb assembly consists of 17 autosomes, 1 X chromosome, and 127 unplaced scaffolds, with an N50 of 370 Mb and Arachnida (odb10; 2934 genes) BUSCO of 96.7%. By comparing 20 additional spider genomes from 15 families, we find mygalomo...

Effect of Cover Cropping on the Abundance, Community Composition and Functional Diversity of Ground-Dwelling Arthropods in a Mediterranean Olive Grove

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Effect of Cover Cropping on the Abundance, Community Composition and Functional Diversity of Ground-Dwelling Arthropods in a Mediterranean Olive Grove

Abstract

Cover cropping is increasingly recognized as a biodiversity-friendly practice in Mediterranean agriculture. However, its impact on ground-dwelling arthropods in olive groves remains insufficiently studied. This study assesses the effects of two perennial cover crops, tall fescue (Festuca arundinacea) and white clover (Trifolium repens) on the abundance, community composition, and functional diversity of ground-dwelling arthropods in a traditional olive grove in Crete, Greece. From April to September 2023, arthropods were sampled bi-weekly using pitfall traps and classified by taxonomic identity and functional traits, with particular focus on spiders (Araneae) and ground beetles (Carabidae). Cover cropping significantly increased total arthropod abundance compared to a control, with clover favoring omnivores and saprophages, and fescue promoting predatory taxa. Fescue plots exhibited the highest abundance of spiders and carabids, as well as greater carabid species richness and functional diversity. Although spider beta diversity differed across treatments, their functional diversity remained unchanged. Our findings indicate that perennial cover crops, especially fescue, enhance ground predator diversity and may contribute to natural pest regulation in Mediterranean olive groves, offering a sustainable alternative to conventional management.

Angelioudakis, T., Koliopoulos, G., & Stathakis, T. (2025). Effect of Cover Cropping on the Abundance, Community Composition and Functional Diversity of Ground-Dwelling Arthropods in a Mediterranean Olive Grove. Diversity, 17(9), 621. https://doi.org/10.3390/d17090621