The evolution of nervous system centralization

Arendt, Detlev; Denes, Alexandru S.; Jékely, Gáspár; Tessmar-Raible, Kristin

doi:10.1093/acprof:oso/9780199549429.003.0007

Cited by 28 publications

(44 citation statements)

References 961 publications

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“…This should be re-emphasized in the post-genome era on cnidarian biology. Among bilaterian animals, it seems undeniable that the Bmp signal is essential for patterning the neural tissue along the dorsoventral axis in their common ancestor (Arendt et al 2008). However, the assumption arose from the data on an enteropneust Saccoglossus that the Bmp/Chordin-mediated centralization of the nervous system in both arthropods and chordates came up independently in these two groups after they diverged (Lowe et al 2006;Lowe 2008) has yet to be supported by other model animals that should include cnidarians.…”

Section: Resultsmentioning

confidence: 99%

Cnidarians and the evolutionary origin of the nervous system

2009

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Cnidarians are widely regarded as one of the first organisms in animal evolution possessing a nervous system. Conventional histological and electrophysiological studies have revealed a considerable degree of complexity of the cnidarian nervous system. Thanks to expressed sequence tags and genome projects and the availability of functional assay systems in cnidarians, this simple nervous system is now genetically accessible and becomes particularly valuable for understanding the origin and evolution of the genetic control mechanisms underlying its development. In the present review, the anatomical and physiological features of the cnidarian nervous system and the interesting parallels in neurodevelopmental mechanisms between Cnidaria and Bilateria are discussed.

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Section: Resultsmentioning

confidence: 99%

Cnidarians and the evolutionary origin of the nervous system

2009

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“…Vicarious gene expression patterns and gene networks have been used to test homologies grounded in comparative anatomy, and to propose new homologies where comparative anatomy has failed. Collectively, these homologies have been used to infer the nature of deep ancestors, such as the last common ancestor of Bilateria, to gain insights into the relationship between developmental and organismal evolution (Kimmel 1996;De Robertis 1997;Panganiban et al 1997;Holland and Holland 1999;Tabin et al 1999;Dewel 2000;Jacobs et al 2000;Carroll et al 2001;Cornec and Gilles 2006;Arendt et al 2008;De Robertis 2008;Hejnol and Martindale 2008). The only conceivable test of these reconstructions is paleontological data, not because it is possible to recognize ancestors in the fossil recordFit is not (Nelson 1989), but because some fossil taxa are both taxonomically and temporally proximal to such ancestors, providing better constraint over attempts to infer their nature.…”

Section: Introductionmentioning

confidence: 99%

Are palaeoscolecids ancestral ecdysozoans?

Harvey

Dong

Donoghue

2010

Evolution and Development

144

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The reconstruction of ancestors is a central aim of comparative anatomy and evolutionary developmental biology, not least in attempts to understand the relationship between developmental and organismal evolution. Inferences based on living taxa can and should be tested against the fossil record, which provides an independent and direct view onto historical character combinations. Here, we consider the nature of the last common ancestor of living ecdysozoans through a detailed analysis of palaeoscolecids, an early and extinct group of introvert-bearing worms that have been proposed to be ancestral ecdysozoans. In a review of palaeoscolecid anatomy, including newly resolved details of the internal and external cuticle structure, we identify specific characters shared with various living nematoid and scalidophoran worms, but not with panarthropods. Considered within a formal cladistic context, these characters provide most overall support for a stem-priapulid affinity, meaning that palaeoscolecids are far-removed from the ecdysozoan ancestor. We conclude that previous interpretations in which palaeoscolecids occupy a deeper position in the ecdysozoan tree lack particular morphological support and rely instead on a paucity of preserved characters. This bears out a more general point that fossil taxa may appear plesiomorphic merely because they preserve only plesiomorphies, rather than the mélange of primitive and derived characters anticipated of organisms properly allocated to a position deep within animal phylogeny.

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“…16 In the case of serotonin, it is controversial whether it has a significant role in the ENS of mammals. 51,52 Previous considerations of the evolutionary origins of the CNS suggest that it arose in the common ancestors of the bilateria, urbilateria, 53 even though it is generally agreed that the some deuterostomes (echinoderms and hemichordates) cannot be said to have a CNS 54 (Table 1). If the conservation of neurotransmitter systems is taken into account, as well as similarities in neuronal and synaptic morphologies between cnidarian and other invertebrate and vertebrate nervous systems, 13 an earlier development of a nervous system than in urbilateria can be proposed to have occurred in "ureumetazoa", postulated ancestors of both cnidarians and bilateria.…”

Section: Did An Ancient Nervous System Lead To the Ens In Cnidaria mentioning

confidence: 99%

The first brain: Species comparisons and evolutionary implications for the enteric and central nervous systems

Furness

Stebbing

2017

Neurogastroenterology Motil

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To explore relationships between the ENS and CNS across the animal kingdom. We found that an ENS occurs in all animals investigated, including hydra, echinoderms and hemichordates that do not have a CNS. The general form of the ENS, which consists of plexuses of neurons intrinsic to the gut wall and an innervation that controls muscle movements, is similar in species as varied and as far apart as hydra, sea cucumbers, annelid worms, octopus and humans. Moreover, neurochemical similarities across phyla imply a common origin of the ENS. Investigation of extant species suggests that the ENS developed in animals that preceded the division that led to cnidaria (exemplified by hydra) and bilateria, which includes the vertebrates. The CNS is deduced to be a bilaterian development, later than the divergence from cnidaria. Consistent with the ENS having developed independent of the CNS, reciprocal connections between ENS and CNS occur in mammals, and separate neurons of ENS and CNS origin converge on visceral organs and prevertebral ganglia. We conclude that an ENS arose before and independently of the CNS. Thus the ENS can be regarded as the first brain.

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The evolution of nervous system centralization

Cited by 28 publications

References 961 publications

Cnidarians and the evolutionary origin of the nervous system

Cnidarians and the evolutionary origin of the nervous system

Are palaeoscolecids ancestral ecdysozoans?

The first brain: Species comparisons and evolutionary implications for the enteric and central nervous systems

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