Phylogenomic resolution of sea spider diversification through integration of multiple data classes

• Published in: Molecular Biology and Evolution
• Main Authors: Ballesteros, Jesús A, Setton, Emily V.W., Santibáñez-López, Carlos E., Arango, Claudia P., Brenneis, Georg, Brix, Saskia, Cano Sánchez, Esperanza, López González, Pablo José, Sharma, Prashant P.
• Other Authors: Universidad de Sevilla. Departamento de Zoología
• Format: Article in Journal/Newspaper
• Language: English
• Published: Oxford University Press 2021
• Subjects: Arthropods; Diversification; Mitogenome; Pycnogonida; Ultraconserved; Antarctic; Antarc*
• Online Access: https://idus.us.es/handle//11441/125745

Despite significant advances in invertebrate phylogenomics over the past decade, the higher-level phylogeny of Pycnogonida (sea spiders) remains elusive. Due to the inaccessibility of some small-bodied lineages, few phylogenetic studies have sampled all sea spider families. Previous efforts based on a handful of genes have yielded unstable tree topologies. Here, we inferred the relationships of 89 sea spider species using targeted capture of the mitochondrial genome, 56 conserved exons, 101 ultraconserved elements, and 3 nuclear ribosomal genes. We inferred molecular divergence times by integrating morphological data for fossil species to calibrate 15 nodes in the arthropod tree of life. This integration of data classes resolved the basal topology of sea spiders with high support. The enigmatic family Austrodecidae was resolved as the sister group to the remaining Pycnogonida and the small-bodied family Rhynchothoracidae as the sister group of the robust-bodied family Pycnogonidae. Molecular divergence time estimation recovered a basal divergence of crown group sea spiders in the Ordovician. Comparison of diversification dynamics with other marine invertebrate taxa that originated in the Paleozoic suggests that sea spiders and some crustacean groups exhibit resilience to mass extinction episodes, relative to mollusk and echinoderm lineages. Deutsche Forschungsgemeinschaft BR5039/3-1 National Science Foundation ANT-0551969, ANT-0440577 Ministerio de Economía y Competitividad POL2006-06399/CGL, CTM2012-39350- C02-01 Antarctic Science AA3010 National Science Foundation IOS-1552610