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The anatomy and development of the nervous system in Magelonidae (Annelida) – insights into the evolution of the annelid brain

dc.contributor.authorBeckers, Patrick
dc.contributor.authorHelm, Conrad
dc.contributor.authorBartolomaeus, Thomas
dc.date.accessioned2019-09-01T03:52:49Z
dc.date.available2019-09-01T03:52:49Z
dc.date.issued2019
dc.identifier.urihttp://resolver.sub.uni-goettingen.de/purl?gs-1/16372
dc.description.abstractAbstract Background The annelid anterior central nervous system is often described to consist of a dorsal prostomial brain, consisting of several commissures and connected to the ventral ganglionic nerve cord via circumesophageal connectives. In the light of current molecular phylogenies, our assumptions on the primary design of the nervous system in Annelida has to be reconsidered. For that purpose we provide a detailed investigation of the adult nervous system of Magelonidae – a putatively basally branching annelid family - and studied early stages of the development of the latter. Results Our comparative investigation using an integrative morphological approach shows that the nervous system of Magelonidae is located inside the epidermis. The brain is composed of an anterior compact neuropil and posteriorly encircles the prostomial coelomic cavities. From the brain two lateral medullary cords branch off which fuse caudally. Prominent brain structures such as nuchal organs, ganglia or mushroom bodies are absent and the entire nervous system is medullary. Our investigations also contradict previous investigations and present an updated view on established assumptions and descriptions. Conclusion The comprehensive dataset presented herein enables a detailed investigation of the magelonid anterior central nervous system for the first time. The data reveal that early in annelid evolution complexity of brains and anterior sensory structures rises. Polymorphic neurons in clusters and distinct brain parts, as well as lateral organs - all of which are not present in outgroup taxa and in the putative magelonid sister group Oweniidae - already evolved in Magelonidae. Commissures inside the brain, ganglia and nuchal organs, however, most likely evolved in the stem lineage of Amphinomidae + Sipuncula and Pleistoannelida (Errantia+ Sedentaria). The investigation demonstrates the necessity to continuously question established descriptions and interpretations of earlier publications and the need for transparent datasets. Our results also hint towards a stronger inclusion of larval morphology and developmental investigations in order to understand adult morphological features, not only in Annelida.
dc.description.sponsorshipOpen-Access-Publikationsfonds 2019
dc.language.isoen
dc.publisherBioMed Central
dc.identifier.bibliographicCitationBMC Evolutionary Biology. 2019 Aug 28;19(1):173
dc.rightsopenAccess
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.titleThe anatomy and development of the nervous system in Magelonidae (Annelida) – insights into the evolution of the annelid brain
dc.typejournalArticle
dc.identifier.doi10.1186/s12862-019-1498-9
dc.type.versionpublishedVersion
dc.date.updated2019-09-01T03:52:49Z
dc.rights.holderThe Author(s).
dc.bibliographicCitation.volume19
dc.bibliographicCitation.issue1
dc.type.subtypejournalArticle
dc.identifier.pmid31462293
dc.bibliographicCitation.articlenumber173
dc.bibliographicCitation.journalBMC Evolutionary Biology


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