02336nas a2200253 4500008004100000022001400041245010900055210006900164260001500233300001600248490000700264520155700271653001701828653001401845653001301859653001601872653001601888653001501904100002201919700003001941700003001971700002102001856006002022 2021 eng d a1537-171900aPhylogenomic Analysis of Velvet Worms (Onychophora) Uncovers an Evolutionary Radiation in the Neotropics0 aPhylogenomic Analysis of Velvet Worms Onychophora Uncovers an Ev c24/08/2021 a5391 - 54040 v383 a

Onychophora (“velvet worms”) are charismatic soil invertebrates known for their status as a “living fossil,” their phylogenetic affiliation to arthropods, and their distinctive biogeographic patterns. However, several aspects of their internal phylogenetic relationships remain unresolved, limiting our understanding of the group’s evolutionary history, particularly with regard to changes in reproductive mode and dispersal ability. To address these gaps, we used RNA sequencing and phylogenomic analysis of transcriptomes to reconstruct the evolutionary relationships and infer divergence times within the phylum. We recovered a fully resolved and well-supported phylogeny for the circum-Antarctic family Peripatopsidae, which retains signals of Gondwanan vicariance and showcases the evolutionary lability of reproductive mode in the family. Within the Neotropical clade of Peripatidae, though, we found that amino acid-translated sequence data masked nearly all phylogenetic signal, resulting in highly unstable and poorly supported relationships. Analyses using nucleotide sequence data were able to resolve many more relationships, though we still saw discordant phylogenetic signal between genes, probably indicative of a rapid, mid-Cretaceous radiation in the group. Finally, we hypothesize that the unique reproductive mode of placentotrophic viviparity found in all Neotropical peripatids may have facilitated the multiple inferred instances of over-water dispersal and establishment on oceanic islands.

10abiogeography10adispersal10aGondwana10aOnychophora10asystematics10avicariance1 aBaker, Caitlin, M1 aBuckman-Young, Rebecca, S1 aCosta, Cristiano, Sampaio1 aGiribet, Gonzalo uhttps://academic.oup.com/mbe/article/38/12/5391/635704802671nas a2200301 4500008004100000022001400041245008200055210006900137260001500206300001400221490000700235520176100242653003502003653001302038653003402051653002502085653001602110653001502126100001802141700001802159700002802177700002202205700001702227700001702244700001702261700003102278856006002309 2020 eng d a0737-403800aEvolutionary History of Major Chemosensory Gene Families across Panarthropoda0 aEvolutionary History of Major Chemosensory Gene Families across  c04/08/2020 a3601-36150 v373 a

Chemosensory perception is a fundamental biological process of particular relevance in basic and applied arthropod research. However, apart from insects, there is little knowledge of specific molecules involved in this system, which is restricted to a few taxa with uneven phylogenetic sampling across lineages. From an evolutionary perspective, onychophorans (velvet worms) and tardigrades (water bears) are of special interest since they represent the closest living relatives of arthropods, altogether comprising the Panarthropoda. To get insights into the evolutionary origin and diversification of the chemosensory gene repertoire in panarthropods, we sequenced the antenna- and head-specific transcriptomes of the velvet worm Euperipatoides rowelli and analyzed members of all major chemosensory families in representative genomes of onychophorans, tardigrades, and arthropods. Our results suggest that the NPC2 gene family was the only family encoding soluble proteins in the panarthropod ancestor and that onychophorans might have lost many arthropod-like chemoreceptors, including the highly conserved IR25a receptor of protostomes. On the other hand, the eutardigrade genomes lack genes encoding the DEG-ENaC and CD36-sensory neuron membrane proteins, the chemosensory members of which have been retained in arthropods; these losses might be related to lineage-specific adaptive strategies of tardigrades to survive extreme environmental conditions. Although the results of this study need to be further substantiated by an increased taxon sampling, our findings shed light on the diversification of chemosensory gene families in Panarthropoda and contribute to a better understanding of the evolution of animal chemical senses.

10aantenna-specific transcriptome10aBITACORA10achemosensory-related proteins10acomparative genomics10aOnychophora10aTardigrada1 aVizueta, Joel1 aEscuer, Paula1 aFrías-López, Cristina1 aGuirao-Rico, Sara1 aHering, Lars1 aMayer, Georg1 aRozas, Julio1 aSánchez-Gracia, Alejandro uhttps://academic.oup.com/mbe/article/37/12/3601/5880555