Phylogenomics of the longitarsal Colossendeidae: The evolutionary history of an Antarctic sea spider radiation

Dietz, Lars; Dömel, Jana S.; Leese, Florian; Mahon, Andrew R.; Mayer, Christoph

doi:10.1016/j.ympev.2019.04.017

Cited by 20 publications

(45 citation statements)

References 49 publications

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“…Exceptions included Decolopoda (a result attributable to the lack of any loci that include both Decolopoda species) and Achelia (sampled with three terminals). Our results corroborated the non-monophyly of Colossendeis due to the nested placement of species with supernumerary segments (e.g., the genera Decolopoda and Dodecolopoda) [34], and additionally reveal here the non-monophyly of Nymphon due to the nested placement of Boreonymphon and the 10-legged genus Pentanymphon. By contrast, the 10-legged genus Pentapycnon was recovered as the sister group to a monophyletic Pycnogonum.…”

Section: (A) Phylogenomic Relationships Of Pycnogonidasupporting

confidence: 86%

“…In deep-sea isopods, diversification in the deep sea occurred in parallel with anoxic events, with the earliest radiation dated to the early Permian and subsequent episodes of rapid colonization and radiation [55]. Such processes could partly explain the oddities of sea spider biogeography, such as the concentration of their diversity in Antarctica, but the role that the Southern Ocean has played as a potential center of endemism is not clear based on our results, as it requires investigation at lower taxonomic levels [2,34,[61][62][63][64][65][66][67]. In Pycnogonida, specific radiation events in Antarctica that have generated endemicity have occurred at least within Nymphon, Pallenopsis, Ammothea and Colossendeidae.…”

Section: (C) Combining Data Classes Overcomes Limitations Of Individumentioning

confidence: 89%

“…Fortuitously, population genetic works have begun tackling such questions at shallower taxonomic scales (within species or species groups), with high levels of precision [34,[61][62][63][64][65][66][67].…”

Section: (C) Combining Data Classes Overcomes Limitations Of Individumentioning

confidence: 99%

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

Ballesteros

Setton

López

et al. 2020

Preprint

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Despite significant advances in invertebrate phylogenomics over the past decade, the higher-level phylogeny of Pycnogonida (sea spiders) remains elusive. This group of arthropods appeared early in the fossil record, with the oldest unambiguous fossils dating to the Silurian. Due to the inaccessibility of some small-bodied lineages, few phylogenetic studies have sampled all sea spider families. In addition, previous efforts based on a handful of genes have yielded unstable tree topologies from one analytical approach to the next. Here, we inferred the relationships of 89 sea spider species using targeted capture of the mitochondrial genome, 56 conserved exons, 101 ultraconserved elements, and three 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 Page 3 of 31 robust-bodied family Pycnogonidae. This stable, dated phylogeny of Pycnogonida enables confident polarization of of cephalic appendage loss across pycnogonid families, with the consistent lack of the adult chelifore in a grade of basally diverging lineages. 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.

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Section: (A) Phylogenomic Relationships Of Pycnogonidasupporting

confidence: 86%

Section: (C) Combining Data Classes Overcomes Limitations Of Individumentioning

confidence: 89%

See 1 more Smart Citation

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

Ballesteros

Setton

López

et al. 2020

Preprint

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“…For target hybrid enrichment, a specific bait set was designed for C. megalonyx following the workflow described by Mayer et al (2016). The bait design was based on genes that are single copy in spider genomes and that are present in a transciptome assembly of C. megalonyx (see Dietz et al 2019 for details and bait sequences). The bait set included a total number of 12,014 baits covering 3682 bait regions from 1607 eukaryotic orthologous genes (EOGs).…”

Section: Target Hybrid Enrichmentmentioning

confidence: 99%

“…One taxon consisting of a remarkable amount of recently diverged lineages are pycnogonids (Mahon et al 2008; Krabbe et al 2010;Arango et al 2011;Weis and Melzer 2012;Weis et al 2014;Dietz et al 2015Dietz et al , 2019Dömel et al 2015Dömel et al , 2017Ballesteros et al 2020). Pycnogonids, also called sea spiders, are a group of exclusively marine arthropods that are especially diverse in the Southern Ocean (Aronson et al 2007), showing high endemism to this region (Munilla and Soler-Membrives 2009).…”

Section: Introductionmentioning

confidence: 99%

Analyzing drivers of speciation in the Southern Ocean using the sea spider species complex Colossendeis megalonyx as a test case

et al. 2020

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Colossendeis megalonyx Hoek, 1881 has the broadest distribution of all sea spiders in the Southern Ocean. Previous studies have detected several evolutionarily young lineages within this taxon and interpreted them as a result of allopatric speciation in a few shelf refuges during glacial maxima. However, alternative scenarios such as ecological speciation in sympatry have rarely been considered or tested. Here, we generated the most extensive genomic and morphometric data set on the C. megalonyx species complex to (i) comprehensively describe species diversity, (ii) explore intraspecific connectivity between populations located around Antarctica, and (iii) systematically test for positive selection indicative of adaptive speciation. We successfully applied a target hybrid enrichment approach and recovered all 1607 genes targeted. Phylogenomic analysis was consistent with previous findings and, moreover, increased the resolution of branching within lineages. We found specimens of phylogenetically well-separated lineages occurring in sympatry to be genetically distinct from each other and gene flow between geographically separated populations of the same lineages to be restricted. Evidence for positive selection was found for four genes associated with structural and neuronal functions. Hence, there is an indication for positive selection in the C. megalonyx species complex, yet its specific contribution to the speciation process remains to be explored further. Finally, morphometric analyses revealed multiple significant differences between lineages, but a clear separation proved difficult. Our study highlights the relevance of positive selection as a potential driver for speciation in the Southern Ocean.

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Multiple Doris “kerguelenensis” (Nudibranchia) species span the Antarctic Polar Front

Maroni

Wilson

2022

Ecology and Evolution

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Despite strong historical biogeographical links between benthic faunal assemblages of the Magellan region of South America and the Antarctic Peninsula, very few studies have documented contemporary movement and gene flow in or out of the Southern Ocean, especially across the Antarctic Polar Front (APF). In fact, oceanographic barriers such as the APF and Antarctica's long geologic isolation have substantially separated the continents and facilitated the evolution of endemic marine taxa found within the Antarctic region. The Southern Ocean benthic sea slug complex, Doris “kerguelenensis,” are a group of direct‐developing, simultaneous hermaphrodites that lack a dispersive larval stage. To date, there are 59 highly divergent species known within this complex. Here, we provide evidence to show intraspecific genetic connectivity occurs across the APF for multiple species within the D. “kerguelenensis” nudibranch species complex. We addressed questions of genetic connectivity by examining the phylogeographic structure of the three best‐sampled D. “kerguelenensis” species and another three trans‐APF species using the protein coding mtDNA gene, cytochrome oxidase I. We also highlight alternative refugia uses among species with the same life history traits (i.e., benthic and direct developers) and for some species, extremely large distributions are established (e.g., circumpolarity). By improving our sampling of these nudibranchs, we gain better insight into the population structure and connectivity of the Antarctic region. This work also demonstrates how difficult it is to make generalizations across Antarctic marine species, even among ecologically‐similar, closely related species.

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Phylogenomics of the longitarsal Colossendeidae: The evolutionary history of an Antarctic sea spider radiation

Cited by 20 publications

References 49 publications

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

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

Analyzing drivers of speciation in the Southern Ocean using the sea spider species complex Colossendeis megalonyx as a test case

Multiple Doris “kerguelenensis” (Nudibranchia) species span the Antarctic Polar Front

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