scholarly journals cis-regulatory change associated with snake body plan evolution

2013 ◽  
Vol 110 (26) ◽  
pp. 10473-10474 ◽  
Author(s):  
J. H. Mansfield
Keyword(s):  
Body Plan ◽  
Regulatory Change ◽  
Body Plan Evolution

scholarly journals Problematica old and new

2008 ◽  
Vol 363 (1496) ◽  
pp. 1503-1512 ◽  
Author(s):  
Ronald A Jenner ◽  
D.Timothy J Littlewood
Keyword(s):  
Molecular Phylogenetics ◽  
Body Plan ◽  
Phylogeny Reconstruction ◽  
Phylogenetic Placement ◽  
Genomic Markers ◽  
Body Plan Evolution ◽  
Metazoan Phylogeny

Problematica are taxa that defy robust phylogenetic placement. Traditionally the term was restricted to fossil forms, but it is clear that extant taxa may be just as difficult to place, whether using morphological or molecular (nucleotide, gene or genomic) markers for phylogeny reconstruction. We discuss the kinds and causes of Problematica within the Metazoa, as well as criteria for their recognition and possible solutions. The inclusive set of Problematica changes depending upon the nature and quality of (homologous) data available, the methods of phylogeny reconstruction and the sister taxa inferred by their placement or displacement. We address Problematica in the context of pre-cladistic phylogenetics, numerical morphological cladistics and molecular phylogenetics, and focus on general biological and methodological implications of Problematica, rather than presenting a review of individual taxa. Rather than excluding Problematica from phylogeny reconstruction, as has often been preferred, we conclude that the study of Problematica is crucial for both the resolution of metazoan phylogeny and the proper inference of body plan evolution.

scholarly journals Naked chancelloriids from the lower Cambrian of China show evidence for sponge-type growth

2018 ◽  
Vol 285 (1881) ◽  
pp. 20180296 ◽  
Author(s):  
Pei-Yun Cong ◽  
Thomas H. P. Harvey ◽  
Mark Williams ◽  
David J. Siveter ◽  
Derek J. Siveter ◽  
...  
Keyword(s):  
Lower Cambrian ◽  
Body Cavity ◽  
Body Plan ◽  
The Body ◽  
Phylogenetic Position ◽  
Axis Formation ◽  
Large Size ◽  
Show Evidence ◽  
Body Plan Evolution ◽  
Extinct Group

Chancelloriids are an extinct group of spiny Cambrian animals of uncertain phylogenetic position. Despite their sponge-like body plan, their spines are unlike modern sponge spicules, but share several features with the sclerites of certain Cambrian bilaterians, notably halkieriids. However, a proposed homology of these ‘coelosclerites' implies complex transitions in body plan evolution. A new species of chancelloriid, Allonnia nuda , from the lower Cambrian (Stage 3) Chengjiang Lagerstätte is distinguished by its large size and sparse spination, with modified apical sclerites surrounding an opening into the body cavity. The sclerite arrangement in A. nuda and certain other chancelloriids indicates that growth involved sclerite addition in a subapical region, thus maintaining distinct zones of body sclerites and apical sclerites. This pattern is not seen in halkieriids, but occurs in some modern calcarean sponges. With scleritome assembly consistent with a sponge affinity, and in the absence of cnidarian- or bilaterian-grade features, it is possible to interpret chancelloriids as sponges with an unusually robust outer epithelium, strict developmental control of body axis formation, distinctive spicule-like structures and, by implication, minute ostia too small to be resolved in fossils. In this light, chancelloriids may contribute to the emerging picture of high disparity among early sponges.

scholarly journals The Cell's View of Animal Body-Plan Evolution

2014 ◽  
Vol 54 (4) ◽  
pp. 658-666 ◽  
Author(s):  
D. C. Lyons ◽  
M. Q. Martindale ◽  
M. Srivastava
Keyword(s):  
Body Plan ◽  
Animal Body ◽  
Body Plan Evolution

scholarly journals Molluscan dorsal-ventral patterning relying on BMP2/4 and Chordin provides insights into spiralian development and bilaterian body plan evolution

2020 ◽  
Author(s):  
Sujian Tan ◽  
Pin Huan ◽  
Baozhong Liu
Keyword(s):  
Nervous System ◽  
Molecular Mechanisms ◽  
Positional Information ◽  
Body Plan ◽  
Bmp Signaling ◽  
Functional Study ◽  
Development Mode ◽  
Larval Nervous System ◽  
Body Plan Evolution

AbstractThe molecular mechanisms of dorsal-ventral (DV) patterning in Spiralia are poorly understood. The few available studies indicate that derived DV patterning mechanisms occurred in particular spiralian lineages and likely were related to the loss of Chordin gene. Here, a functional study of the first spiralian Chordin showed that BMP2/4 and Chordin regulate DV patterning in the mollusk Lottia goshimai, thus revealing the first spiralian case that retains this conserved mechanism. We then showed that Chordin but not BMP2/4 transferred the positional information of the D-quadrant organizer to establish the BMP signaling gradient along the presumed DV axis. Further investigations on the molluscan embryos with influenced DV patterning suggested a role of BMP signaling in regulating the organization of the larval nervous system and indicated that the blastopore localization is correlated with the BMP signaling gradient. These findings provide insights into the evolution of animal DV patterning, the unique development mode of spiralians driven by the D-quadrant organizer, and the evolution of bilaterian body plans.

scholarly journals Skeletal pathologies track body plan evolution in ichthyosaurs

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Judith M. Pardo-Pérez ◽  
Benjamin P. Kear ◽  
Erin E. Maxwell
Keyword(s):  
Body Plan ◽  
Body Plan Evolution
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