scholarly journals Developmental processes in Ediacara macrofossils

2021 ◽  
Vol 288 (1945) ◽  
pp. 20203055
Author(s):  
Scott D. Evans ◽  
Mary L. Droser ◽  
Douglas H. Erwin
Keyword(s):  
Nervous System ◽  
White Sea ◽  
Phylogenetic Position ◽  
Phylogenetic Groups ◽  
Developmental Processes ◽  
Apparent Lack ◽  
Genetic Pathways ◽  
Metazoan Evolution ◽  
Ediacara Biota ◽  
Early Metazoan

The Ediacara Biota preserves the oldest fossil evidence of abundant, complex metazoans. Despite their significance, assigning individual taxa to specific phylogenetic groups has proved problematic. To better understand these forms, we identify developmentally controlled characters in representative taxa from the Ediacaran White Sea assemblage and compare them with the regulatory tools underlying similar traits in modern organisms. This analysis demonstrates that the genetic pathways for multicellularity, axial polarity, musculature, and a nervous system were likely present in some of these early animals. Equally meaningful is the absence of evidence for major differentiation of macroscopic body units, including distinct organs, localized sensory machinery or appendages. Together these traits help to better constrain the phylogenetic position of several key Ediacara taxa and inform our views of early metazoan evolution. An apparent lack of heads with concentrated sensory machinery or ventral nerve cords in such taxa supports the hypothesis that these evolved independently in disparate bilaterian clades.

scholarly journals Metazoan evolution of glutamate receptors reveals unreported phylogenetic groups and divergent lineage-specific events

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
David Ramos-Vicente ◽  
Jie Ji ◽  
Esther Gratacòs-Batlle ◽  
Gemma Gou ◽  
Rita Reig-Viader ◽  
...  
Keyword(s):  
Nervous System ◽  
Ion Channels ◽  
Synaptic Transmission ◽  
Glutamate Receptors ◽  
Synaptic Strength ◽  
Phylogenetic Study ◽  
Phylogenetic Groups ◽  
Metazoan Evolution ◽  
Class Iv

Glutamate receptors are divided in two unrelated families: ionotropic (iGluR), driving synaptic transmission, and metabotropic (mGluR), which modulate synaptic strength. The present classification of GluRs is based on vertebrate proteins and has remained unchanged for over two decades. Here we report an exhaustive phylogenetic study of GluRs in metazoans. Importantly, we demonstrate that GluRs have followed different evolutionary histories in separated animal lineages. Our analysis reveals that the present organization of iGluRs into six classes does not capture the full complexity of their evolution. Instead, we propose an organization into four subfamilies and ten classes, four of which have never been previously described. Furthermore, we report a sister class to mGluR classes I-III, class IV. We show that many unreported proteins are expressed in the nervous system, and that new Epsilon receptors form functional ligand-gated ion channels. We propose an updated classification of glutamate receptors that includes our findings.

Phylogenetic position of sponges in early metazoan evolution and bionic applications of siliceous sponge spicules

2007 ◽  
Vol 52 (22) ◽  
pp. 3029-3040 ◽  
Author(s):  
Werner E. G. Müller ◽  
XiaoHong Wang ◽  
LingSen Zeng ◽  
Heinz C. Schröder
Keyword(s):  
Phylogenetic Position ◽  
Siliceous Sponge ◽  
Metazoan Evolution ◽  
Sponge Spicules ◽  
Early Metazoan

Notes on the generic position of Brassica deserti (Brassicaceae)

2019 ◽  
Vol 66 (1-2) ◽  
pp. 89-93
Author(s):  
Jotham Ziffer-Berger ◽  
Alexandra Keren-Keiserman ◽  
Adi Doron-Faigenboim ◽  
Klaus Mummenhoff ◽  
Oz Barazani
Keyword(s):  
Mediterranean Area ◽  
Morphological Data ◽  
Phylogenetic Position ◽  
Molecular Tools ◽  
East Mediterranean ◽  
Phylogenetic Groups ◽  
5.8S Rdna ◽  
The Core ◽  
Generic Position ◽  
History Of

Molecular tools provide new insights into phylogenetic relationships of plant species, and by relating phylogenetic groups to their geographical distribution, we can cast light upon the evolution history of plant clades. In the current study, we evaluated the phylogenetic position of the Sinai endemic Brassica deserti (Brassicaceae), later renamed as Erucastrum deserti, based on morphological data and 5.8S rDNA and ITS (Internal Transcribed Spacer) regions. Our results indicate that B. deserti belongs to an East-Mediterranean – Saharo Arabian clade and was not assigned to the core Brassica and Erucastrum clades, respectively, which evolved in the West Mediterranean area. We tentatively conclude that Brassica deserti evolved independently of core Brassica and Erucastrum.

The Ediacaran biota and early metazoan evolution

1985 ◽  
Vol 122 (1) ◽  
pp. 77-81 ◽  
Author(s):  
S. Conway Morris
Keyword(s):  
Metazoan Evolution ◽  
Early Metazoan

Two new species of marine flatworm from southern China facilitate determination of the phylogenetic position of the genus Nerpa Marcus, 1948 and the histochemical structure of the nervous system in the genus Paucumara Sluys, 1989 (Platyhelminthes, Tricladida, Maricola)

Zootaxa ◽  
2019 ◽  
Vol 4568 (1) ◽  
pp. 149 ◽  
Author(s):  
JIA-JIA CHEN ◽  
WEI-XUAN LI ◽  
RONALD SLUYS ◽  
MING-QI WU ◽  
LEI WANG ◽  
...  
Keyword(s):  
Nervous System ◽  
New Species ◽  
Southern China ◽  
Dorsal Side ◽  
The Body ◽  
Integrative Approach ◽  
Phylogenetic Position ◽  
Nerve Structure ◽  
Two New Species ◽  
Copulatory Position

Two new species of flatworm, collected from a beach at eastern Shenzhen, China, were studied through an integrative approach by combining morphological, histological, histochemical (acetylcholinesterase, AChE), and molecular (18S r- DNA) data. These species belong to two genera of marine triclads, previously unrecorded from China, viz. Nerpa Marcus, 1948 and Paucumara Sluys, 1989.        Nerpa fistulata Wang & Chen, sp. nov. is characterized by: transparent body; principally pentamerous intestine with three distinct commissures; two very large, prepharyngeal testis follicles; a semi-circular lens in each eye cup; a penis papilla provided with a chitinized, pointed stylet; lateral bursae communicating with the oviduct and opening ventrally to the exterior via a duct. Phylogenetically N. fistulata groups with one member of the family Bdellouridae. This new, Chinese species of Nerpa introduces a major geographic disjunction, as the type species N. evelinae was described from the bay of Santos, Brazil, so that the genus is now known from both Atlantic as well as Pacific coasts.        The species Paucumara falcata Wang & Li, sp. nov. is characterized by: three distinct pale yellow transverse pigmentation bands on its dorsal side, between which some snowflake-like specks are randomly distributed, and a brown transverse band anteriorly to the eyes; 8–11 testicular follicles on either side of the body, the follicles extending from immediately behind the ovaries to half-way along the pharyngeal pocket; a musculo-parenchymatic organ with a sclerotic, curved tip projecting from the anterior wall of the male atrium, ventrally to the root of the penis papilla. Phylogenetically P. falcata groups with its congener P. trigonocephala, with the genus Paucumara forming the sister taxon of the genus Ectoplana. Comparison of the nerve structure of P. falcata, as revealed by AChE histochemistry, with that of eight other species of triclad suggested that the nervous system of marine planarians is simpler than that of species of freshwater planarians, but revealed also that the nerve structure is rather variable among species.        The copulatory position exhibited by two partners in Paucumara falcata is remarkable in that they intertwine, with their heads pointing downwards and the tails pointing upwards, the entire process lasting about 10 min. Such a copulatory position has never before been reported for triclad flatworms. 

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