When Tarantula Venom Comes from a Misnamed Spider: The Importance of Taxonomic Accuracy in Theraphosid Toxinology

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  When Tarantula Venom Comes from a Misnamed Spider: The Importance of Taxonomic Accuracy in Theraphosid Toxinology I am very happy to share my most recent publication in Toxicon. This is a particularly meaningful publication for me because it brings together two areas that have become an important part of my work and personal interests: tarantulas and toxinology. At first glance, taxonomy and venom research may seem like two very different fields. In reality, they are closely connected. Before we can properly study the venom of a spider, we need to know which spider we are actually studying. Why the Name Matters A scientific name is much more than a label attached to an animal. It connects that animal to everything we report about it, including its biology, distribution, behavior, venom, toxins, and even its potential medical importance. When a tarantula is incorrectly identified, or when an outdated name continues to be used without considering changes in taxonomy, the problem ca...

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 mygalomorphs (trapdoor spiders and their kin) generally possess more repetitive genomes with similar composition compared to their much more diverse sister lineage, the araneomorphs. We report mygalomorphs recover a lower number of completed BUSCOs than araneomorph spiders, a finding not correlated with sequencing coverage, as mygalomorphs have a portion of missing or derived BUSCOs in the current arachnid dataset. Across the Araneoidea (orb-weaving spiders and their kin), there is a correlation between decreasing genome size and repeat content, suggesting repetitive elements are being lost or removed. Importantly, visualization of macrosynteny across available genomes highlights structural rearrangements and allows identification of previously unreported sex chromosomes. This new, high-quality mygalomorph genome will provide new avenues of exploration for arachnid evolutionary biology.

Image Credit: “Taxonomic revision of the tarantula genus Aphonopelma Pocock, 1901 (Araneae, Mygalomorphae, Theraphosidae) within the United States”, in ZooKeys, volume 560, 2016, DOI:10.3897/zookeys.560.6264, pages 1–340

Briggs, E. J., Noble-Stuen, A. J., & Hamilton, C. A. Big Spider, Big Genome: Chromosome-level genome of a North American tarantula (Aphonopelma marxi) and comparative genomics across 300 million years of spider evolution. Genome Biology and Evolution. https://doi.org/10.1093/gbe/evag081