scholarly journals Subdivision of ancestral scale genetic program underlies origin of feathers and avian scutate scales

2018 ◽  
Author(s):  
Jacob M. Musser ◽  
Günter P. Wagner ◽  
Cong Liang ◽  
Frank A. Stabile ◽  
Alison Cloutier ◽  
...  
Keyword(s):  
Gene Expression ◽  
Evolutionary History ◽  
Theropod Dinosaurs ◽  
Skin Appendages ◽  
Key Factor ◽  
History Of ◽  
Tetrapod Evolution ◽  
Similar Gene ◽  
Complex Evolutionary History

AbstractBirds and other reptiles possess a diversity of feather and scale-like skin appendages. Feathers are commonly assumed to have originated from ancestral scales in theropod dinosaurs. However, most birds also have scaled feet, indicating birds evolved the capacity to grow both ancestral and derived morphologies. This suggests a more complex evolutionary history than a simple linear transition between feathers and scales. We set out to investigate the evolution of feathers via the comparison of transcriptomes assembled from diverse skin appendages in chicken, emu, and alligator. Our data reveal that feathers and the overlapping ‘scutate’ scales of birds share more similar gene expression to each other, and to two types of alligator scales, than they do to the tuberculate ‘reticulate’ scales on bird footpads. Accordingly, we propose a history of skin appendage diversification, in which feathers and bird scutate scales arose from ancestral archosaur body scales, whereas reticulate scales arose earlier in tetrapod evolution. We also show that many “feather-specific genes” are also expressed in alligator scales. In-situ hybridization results in feather buds suggest that these genes represent ancestral scale genes that acquired novel roles in feather morphogenesis and were repressed in bird scales. Our findings suggest that the differential reuse, in feathers, and suppression, in bird scales, of genes ancestrally expressed in archosaur scales has been a key factor in the origin of feathers – and may represent an important mechanism for the origin of evolutionary novelties.

scholarly journals Genetic Diversity of Rice stripe necrosis virus and New Insights into Evolution of the Genus Benyvirus

Viruses ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 737
Author(s):  
Issiaka Bagayoko ◽  
Marcos Giovanni Celli ◽  
Gustavo Romay ◽  
Nils Poulicard ◽  
Agnès Pinel-Galzi ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Variability ◽  
Sierra Leone ◽  
Evolutionary History ◽  
Molecular Diversity ◽  
Genomic Data ◽  
Gene Recombination ◽  
Necrosis Virus ◽  
History Of ◽  
Complex Evolutionary History

The rice stripe necrosis virus (RSNV) has been reported to infect rice in several countries in Africa and South America, but limited genomic data are currently publicly available. Here, eleven RSNV genomes were entirely sequenced, including the first corpus of RSNV genomes of African isolates. The genetic variability was differently distributed along the two genomic segments. The segment RNA1, within which clusters of polymorphisms were identified, showed a higher nucleotidic variability than did the beet necrotic yellow vein virus (BNYVV) RNA1 segment. The diversity patterns of both viruses were similar in the RNA2 segment, except for an in-frame insertion of 243 nucleotides located in the RSNV tgbp1 gene. Recombination events were detected into RNA1 and RNA2 segments, in particular in the two most divergent RSNV isolates from Colombia and Sierra Leone. In contrast to BNYVV, the RSNV molecular diversity had a geographical structure with two main RSNV lineages distributed in America and in Africa. Our data on the genetic diversity of RSNV revealed unexpected differences with BNYVV suggesting a complex evolutionary history of the genus Benyvirus.

Rhizobial plasmids — replication, structure and biological role

2012 ◽  
Vol 7 (4) ◽  
pp. 571-586 ◽  
Author(s):  
Andrzej Mazur ◽  
Piotr Koper
Keyword(s):  
Genome Organization ◽  
Soil Bacteria ◽  
Evolutionary History ◽  
Bacterial Genome ◽  
Biological Role ◽  
Genome Architecture ◽  
Genomic Knowledge ◽  
History Of ◽  
Cryptic Plasmids ◽  
Complex Evolutionary History

AbstractSoil bacteria, collectively named rhizobia, can establish mutualistic relationships with legume plants. Rhizobia often have multipartite genome architecture with a chromosome and several extrachromosomal replicons making these bacteria a perfect candidate for plasmid biology studies. Rhizobial plasmids are maintained in the cells using a tightly controlled and uniquely organized replication system. Completion of several rhizobial genome-sequencing projects has changed the view that their genomes are simply composed of the chromosome and cryptic plasmids. The genetic content of plasmids and the presence of some important (or even essential) genes contribute to the capability of environmental adaptation and competitiveness with other bacteria. On the other hand, their mosaic structure results in the plasticity of the genome and demonstrates a complex evolutionary history of plasmids. In this review, a genomic perspective was employed for discussion of several aspects regarding rhizobial plasmids comprising structure, replication, genetic content, and biological role. A special emphasis was placed on current post-genomic knowledge concerning plasmids, which has enriched the view of the entire bacterial genome organization by the discovery of plasmids with a potential chromosome-like role.

A total evidence approach using palynological characters to infer the complex evolutionary history of the Asian Impatiens (Balsaminaceae)

Taxon ◽  
2012 ◽  
Vol 61 (2) ◽  
pp. 355-367 ◽  
Author(s):  
Steven B. Janssens ◽  
Yi Song Wilson ◽  
Yong-Ming Yuan ◽  
Anne Nagels ◽  
Erik F. Smets ◽  
...  
Keyword(s):  
Evolutionary History ◽  
Total Evidence ◽  
History Of ◽  
Complex Evolutionary History

scholarly journals Current perspectives on the evolution of birds

2008 ◽  
Vol 77 (2) ◽  
pp. 109-116 ◽  
Author(s):  
Per G.P. Ericson
Keyword(s):  
Evolutionary History ◽  
Genetic Data ◽  
Morphological Characters ◽  
Current Understanding ◽  
Sources Of Information ◽  
Theropod Dinosaurs ◽  
History Of ◽  
Evolution Of Birds ◽  
The Many ◽  
Rapid Radiations

The paper summarizes the current understanding of the evolution and diversification of birds. New insights into this field have mainly come from two fundamentally different, but complementary sources of information: the many newly discovered Mesozoic bird fossils and the wealth of genetic analyses of living birds at various taxonomic levels. The birds have evolved from theropod dinosaurs from which they can be defined by but a few morphological characters. The early evolutionary history of the group is characterized by the extinctions of many major clades by the end of the Cretaceous, and by several periods of rapid radiations and speciation. Recent years have seen a growing consensus about the higher-level relationships among living birds, at least as can be deduced from genetic data.

scholarly journals ANALYSIS OFALEXANDRIUM TAMARENSE(DINOPHYCEAE) GENES REVEALS THE COMPLEX EVOLUTIONARY HISTORY OF A MICROBIAL EUKARYOTE1

2012 ◽  
Vol 48 (5) ◽  
pp. 1130-1142 ◽  
Author(s):  
Cheong Xin Chan ◽  
Marcelo B. Soares ◽  
Maria F. Bonaldo ◽  
Jennifer H. Wisecaver ◽  
Jeremiah D. Hackett ◽  
...  
Keyword(s):  
Evolutionary History ◽  
History Of ◽  
Complex Evolutionary History

The conservation of number and location of 18S sites indicates the relative stability of rDNA in species of Pentatomomorpha (Heteroptera)

Genome ◽  
2013 ◽  
Vol 56 (7) ◽  
pp. 425-429 ◽  
Author(s):  
Vanessa Bellini Bardella ◽  
Thiago Fernandes ◽  
André Luís Laforga Vanzela
Keyword(s):  
Sex Chromosomes ◽  
18S Rdna ◽  
Fluorescent In Situ Hybridization ◽  
Evolutionary History ◽  
Conclusive Evidence ◽  
Fish Analysis ◽  
Comparative Cytogenetics ◽  
Rdna Sites ◽  
History Of

Fluorescent in situ hybridization (FISH) with rDNA probes has been used for comparative cytogenetics studies in different groups of organisms. Although heteropterans are a large suborder within Hemiptera, studies using rDNA are limited to the infraorder Cimicomorpha, in which rDNA sites are present in the autosomes or sex chromosomes. We isolated and sequenced a conserved 18S rDNA region of Antiteuchus tripterus (Pentatomidae) and used it as a probe against chromosomes of 25 species belonging to five different families of Pentatomomorpha. The clone pAt05, with a length of 736 bp, exhibited a conserved stretch of 590 bp. FISH analysis with the probe pAt05 always demonstrated hybridization signals in sub-terminal positions, except for Euschistus heros. Apparently, there is a tendency for 18S rDNA sites to locate in autosomes, except for Leptoglossus gonagra and Euryophthalmus rufipennis, which showed signals in the m- and sex chromosomes, respectively. Although FISH has produced evidence that rearrangements are involved in rDNA repositioning, whether in different autosomes or between sex and m-chromosomes, we have no conclusive evidence of what were the pathways of these rearrangements based on the evolutionary history of the species studied here. Nevertheless, the diversity in the number of species analyzed here showed a tendency of 18S rDNA to remain among the autosomes.

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