Organogénie de la feuille du Begonia radicans Vellozo et du Begonia scabrida (Begoniaceae)

1992 ◽  
Vol 70 (6) ◽  
pp. 1107-1122 ◽  
Author(s):  
Denis Barabé ◽  
Luc Brouillet ◽  
Charles Bertrand
Keyword(s):  
Key Words ◽  
Evolutionary History ◽  
Leaf Primordia ◽  
Mature Leaf ◽  
The Other ◽  
Leaf Morphogenesis ◽  
Angiosperm Phylogeny ◽  
The Family ◽  
History Of ◽  
Plesiomorphic State

The asymmetrical leaf of Begonia raises both biological and mathematical questions. The leaf organogenesis of two species of Begonia is analyzed in this study, one with asymmetrical, palmately nerved leaves, Begonia scabrida A.DC, the other with quasi-symmetrical, pinnately nerved leaves, Begonia radicans Vellozo. Additional observations on Begonia fagifolia Fischer, a species of the second type, are included for comparison. In the three species studied, the leaf primordia are asymmetrical at initiation, notwithstanding mature leaf symmetry or nervation. In B. radicans, the leaf is asymmetrical at initiation and becomes quasi-symmetrical, while in B. scabrida, it remains asymmetrical throughout. The Begonia leaf thus represents a true case of asymmetry, related to the morphogenetic properties of the vegetative apex. None of the present theories of leaf organogenesis are able to fully account for this phenomenon. Leaf asymmetry represents an ontogenetic constraint in the evolutionary history of Begoniaceae. The hypothesis is presented that the palmately nerved leaf is a plesiomorphic state and the pinnately nerved leaf an apomorphic one that appeared repeatedly within the family. Key words: Begoniaceae, leaf, morphogenesis, angiosperm, phylogeny, apex.

Toward a revision of the bamboo corals: Part 3, deconstructing the Family Isididae

Zootaxa ◽  
2021 ◽  
Vol 5047 (3) ◽  
pp. 247-272
Author(s):  
ESPRIT HEESTAND SAUCIER ◽  
SCOTT C. FRANCE ◽  
LES WATLING
Keyword(s):  
Calcium Carbonate ◽  
Evolutionary History ◽  
The Other ◽  
Genetic Analyses ◽  
The Family ◽  
Family Level ◽  
Current Classification ◽  
History Of

Bamboo corals are distinguished from most other octocorals by an articulated skeleton. The nodes are proteinaceous and sclerite-free while the internodes are composed of non-scleritic calcium carbonate. This articulation of the skeleton was thought to be unique and a strong synapomorphy for the family Isididae. Our phylogeny, based on the amplification of mtMutS and 18S, shows an articulating skeleton with sclerite-free nodes has arisen independently at least five times during the evolutionary history of Octocorallia rather than being a synapomorphy characteristic of a monophyletic bamboo coral clade. The family Isididae is currently composed of four subfamilies (Circinisidinae, Isidinae, Keratoisidinae, and Mopseinae). Not only is the family polyphyletic, but our genetic analyses suggest also the subfamily Isidinae is polyphyletic based on current taxonomic classifications, and Mopseinae is not monophyletic. The type, Isis, is found outside of the well-supported Calcaxonia – Pennatulacea clade where the other members of Isididae cluster. The current classification of the family Isididae does not reflect the evolutionary history of an articulated skeleton. To better reflect the evolutionary history of these taxa we propose that three of the four the subfamilies, the genus Isidoides, and genera within the subfamily Isidinae, be elevated to family level to produce a classification with five families with a bamboo-like skeleton: Chelidonisididae, Isididae, Isidoidae, Keratoisididae, and Mopseidae.  

Systematic evidence from gene duplication and regulation

1990 ◽  
Vol 3 (1) ◽  
pp. 145
Author(s):  
DJ Colgan
Keyword(s):  
Gene Duplication ◽  
Evolutionary History ◽  
Tandem Duplication ◽  
Fragment Length Polymorphism ◽  
Duplicate Genes ◽  
Polymorphism Analysis ◽  
Multiple Origins ◽  
The Family ◽  
History Of ◽  
Phylogenetic Hypotheses

This paper is a review of the use of information regarding the presence of duplicate genes and their regulation in systematics. The review concentrates on data derived from protein electrophoresis and restriction fragment length polymorphism analysis. The appearance of a duplication in a subset of a group of species implies that the members of the subset belong to the same clade. Suppression of the duplication may render this clade apparently paraphyletic, but may itself be informative of relations within the lineage through patterns of loss of expression in all, or some tissues, or through restrictions of the formation of functional heteropolymers in polymeric enzymes. Examples are given of studies which have used such information to establish phylogenetic hypotheses at the family level, to identify an auto- or allo-polyploid origin of polyploid species and to determine whether there have been single or multiple origins of such species. The likelihood of homoplasy in the patterns of appearance and regulation of duplicates depends on the molecular basis of the duplication. In particular, the contrast between the expected consequences of tandem duplication and the expression of pseudogenes emphasises the value of determining the mechanism of the original duplication. Many instances of sporadic gene duplication are now known, and polyploidisation is a common event in the evolutionary history of both plants and animals. So the opportunities to discover duplicationrelated characters will arise in many systematic studies. A program is presented to increase the chances that such useful information will be recognisable during the studies.

Systematics and biogeography of the “Metacryphaeus group” Calmoniidae (Trilobita, Devonian), with comments on adaptive radiations and the geological history of the Malvinokaffric Realm

1993 ◽  
Vol 67 (4) ◽  
pp. 549-570 ◽  
Author(s):  
Bruce S. Lieberman
Keyword(s):  
New Species ◽  
South African ◽  
Evolutionary History ◽  
Geological History ◽  
Parsimony Analysis ◽  
Evolutionary Patterns ◽  
The Family ◽  
History Of ◽  
Adaptive Radiations ◽  
Rapid Diversification

Phylogenetic parsimony analysis was used to classify the Siegenian–Eifelian “Metacryphaeus group” of the family Calmoniidae. Thirty-eight exoskeletal characters for 16 taxa produced a shortest-length cladogram with a consistency index of 0.49. A classification based on retrieving the structure of this cladogram recognizes nine genera: Typhloniscus Salter, Plesioconvexa n. gen., Punillaspis Baldis and Longobucco, Eldredgeia n. gen., Clarkeaspis n. gen., Malvinocooperella n. gen., Wolfartaspis Cooper, Plesiomalvinella Lieberman, Edgecombe, and Eldredge (used to represent the malvinellid clade), and Metacryphaeus Reed. The malvinellid clade is most closely related to a revised monophyletic Metacryphaeus. Typhloniscus is the basal member of the “Metacryphaeus group,” and the monotypic Wolfartaspis is sister to the clade containing the malvinellids and Metacryphaeus. Six new species are diagnosed: Punillaspis n. sp. A, “Clarkeaspis” gouldi, Clarkeaspis padillaensis, Malvinocooperella pregiganteus, Metacryphaeus curvigena, and Metacryphaeus branisai. Primitively, this group has South African and Andean affinities, and its evolutionary history suggests rapid diversification. In addition, evolutionary patterns in this group, and the distribution of character reversals, call into question certain notions about the nature of adaptive radiations. The distributions of taxa may answer questions about the number of marine transgressive/regressive cycles in the Emsian–Eifelian of the Malvinokaffric Realm.

Adaptive convergent evolution of genome proofreading in SARS-CoV2: insights into the Eigen’s paradox

2021 ◽  
Author(s):  
Keerthic Aswin ◽  
Srinivasan Ramachandran ◽  
Vivek T Natarajan
Keyword(s):  
Convergent Evolution ◽  
Genome Stability ◽  
Evolutionary History ◽  
Rna Binding ◽  
Phylogenetic Analyses ◽  
Comparative Genome Analysis ◽  
The Family ◽  
History Of ◽  
Key Residues

AbstractEvolutionary history of coronaviruses holds the key to understand mutational behavior and prepare for possible future outbreaks. By performing comparative genome analysis of nidovirales that contain the family of coronaviruses, we traced the origin of proofreading, surprisingly to the eukaryotic antiviral component ZNFX1. This common recent ancestor contributes two zinc finger (ZnF) motifs that are unique to viral exonuclease, segregating them from DNA proof-readers. Phylogenetic analyses indicate that following acquisition, genomes of coronaviruses retained and further fine-tuned proofreading exonuclease, whereas related families harbor substitution of key residues in ZnF1 motif concomitant to a reduction in their genome sizes. Structural modelling followed by simulation suggests the role of ZnF in RNA binding. Key ZnF residues strongly coevolve with replicase, and the helicase involved in duplex RNA unwinding. Hence, fidelity of replication in coronaviruses is a result of convergent evolution, that enables maintenance of genome stability akin to cellular proofreading systems.

scholarly journals An early fossil remora (Echeneoidea) reveals the evolutionary assembly of the adhesion disc

2013 ◽  
Vol 280 (1766) ◽  
pp. 20131200 ◽  
Author(s):  
Matt Friedman ◽  
Zerina Johanson ◽  
Richard C. Harrington ◽  
Thomas J. Near ◽  
Mark R. Graham
Keyword(s):  
Evolutionary History ◽  
Body Plan ◽  
The Other ◽  
Ontogenetic Changes ◽  
Dorsal Fin ◽  
Early Oligocene ◽  
Stem Group ◽  
History Of ◽  
And Migration ◽  
Fin Spines

The adhesion disc of living remoras (Echeneoidea: Echeneidae) represents one of the most remarkable structural innovations within fishes. Although homology between the spinous dorsal fin of generalized acanthomorph fishes and the remora adhesion disc is widely accepted, the sequence of evolutionary—rather than developmental—transformations leading from one to the other has remained unclear. Here, we show that the early remora † Opisthomyzon (Echeneoidea: †Opisthomyzonidae), from the early Oligocene (Rupelian) of Switzerland, is a stem-group echeneid and provides unique insights into the evolutionary assembly of the unusual body plan characteristic of all living remoras. The adhesion disc of † Opisthomyzon retains ancestral features found in the spiny dorsal fins of remora outgroups, and corroborates developmental interpretations of the homology of individual skeletal components of the disc. † Opisthomyzon indicates that the adhesion disc originated in a postcranial position, and that other specializations (including the origin of pectination, subdivision of median fin spines into paired lamellae, increase in segment count and migration to a supracranial position) took place later in the evolutionary history of remoras. This phylogenetic sequence of transformation finds some parallels in the order of ontogenetic changes to the disc documented for living remoras.

Human Evolution

1984 ◽  
Vol 8 ◽  
pp. 182-198
Author(s):  
Catherine Badgley
Keyword(s):  
Human Evolution ◽  
Evolutionary History ◽  
Pan Paniscus ◽  
Homo Sapiens ◽  
Great Apes ◽  
Sister Group ◽  
The Family ◽  
History Of ◽  
Living Species ◽  
Single Living

The evolutionary history of humans is well understood in outline, compared to that of many other groups of mammals. But human evolution remains enigmatic in its details, and these are compelling both scientifically and personally because they relate to the biological uniqueness of humans. Humans are placed in the primate family Hominidae, which, in traditional classifications, contains a single living species, Homo sapiens. The closest living relatives of humans are great apes: the chimpanzees Pan paniscus and Pan troglodytes, the gorilla Gorilla gorilla, and the orangutan Pongo pygmaeus. These apes have traditionally been placed in the family Pongidae as the sister group of Hominidae. Living Hominidae and Pongidae, together with Hylobatidae (gibbons) comprise the modern representatives of the primate suborder Hominoidea.

scholarly journals Evolution and taxonomy of nematode-associated entomopathogenic bacteria of the genera Xenorhabdus and Photorhabdus: an overview

Symbiosis ◽  
2020 ◽  
Vol 80 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Ewa Sajnaga ◽  
Waldemar Kazimierczak
Keyword(s):  
Evolutionary History ◽  
Entomopathogenic Nematode ◽  
Bacterial Species ◽  
Entomopathogenic Bacteria ◽  
Insecticidal Toxins ◽  
The Family ◽  
The World ◽  
History Of ◽  
Phylogenetic Origin ◽  
Animal Hosts

AbstractEntomopathogenic bacteria from the genera Photorhabdus and Xenorhabdus are closely related Gram-negative bacilli from the family Enterobacteriaceae (γ-Proteobacteria). They establish obligate mutualistic associations with soil nematodes from the genera Steinernema and Heterorhabditis to facilitate insect pathogenesis. The research of these two bacterial genera is focused mainly on their unique interactions with two different animal hosts, i.e. nematodes and insects. So far, studies of the mutualistic bacteria of nematodes collected from around the world have contributed to an increase in the number of the described Xenorhabdus and Photorhabdus species. Recently, the classification system of entomopatogenic nematode microsymbionts has undergone profound revision and now 26 species of the genus Xenorhabdus and 19 species of the genus Photorhabdus have been identified. Despite their similar life style and close phylogenetic origin, Photorhabdus and Xenorhabdus bacterial species differ significantly in e.g. the nematode host range, symbiotic strategies for parasite success, and arrays of released antibiotics and insecticidal toxins. As the knowledge of the diversity of entomopathogenic nematode microsymbionts helps to enable the use thereof, assessment of the phylogenetic relationships of these astounding bacterial genera is now a major challenge for researchers. The present article summarizes the main information on the taxonomy and evolutionary history of Xenorhabdus and Photorhabdus, entomopathogenic nematode symbionts.

XVI.—Quantitative Evolution. III. Dp-ages of Gramineæ

1938 ◽  
Vol 57 ◽  
pp. 221-227
Author(s):  
James Small
Keyword(s):  
Time Scale ◽  
Evolutionary History ◽  
Geological Time ◽  
Exponential Curve ◽  
The Family ◽  
History Of ◽  
Geological Origin ◽  
Fossil Records

Applying Udny Yule's formulæ (1924) to the Compositæ, Small (1937) found that the average ages in doubling periods (Dp-ages) of the tribes of Compositæ, when plotted against a time-scale, gave points on an exponential curve called the BAT curve. If this curve is characteristic of average families of Angiosperms it should be possible to place the Dp-ages of tribes within other families on this curve as plotted against geological time, and thus obtain an order of geological origin which is quite independent of actual fossil records and which can be checked against any facts known concerning the evolutionary history of the family.

Karyotype Evolution and Distinct Evolutionary History of the W Chromosomes in Swallows (Aves, Passeriformes)

2019 ◽  
Vol 158 (2) ◽  
pp. 98-105 ◽  
Author(s):  
Suziane A. Barcellos ◽  
Rafael Kretschmer ◽  
Marcelo S. de Souza ◽  
Alice L. Costa ◽  
Tiago M. Degrandi ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Evolutionary History ◽  
Karyotype Evolution ◽  
Sex Chromosome ◽  
Repetitive Sequences ◽  
Z Chromosome ◽  
W Chromosome ◽  
The Family ◽  
Agnor Staining ◽  
History Of

As in many other bird groups, data on karyotype organization and distribution of repetitive sequences are also lacking in species belonging to the family Hirundinidae. Thus, in the present study, we analyzed the karyotypes of 3 swallow species (Progne tapera, Progne chalybea, and Pygochelidon cyanoleuca) by Giemsa and AgNOR staining, C-banding, and FISH with 11 microsatellite sequences. The diploid chromosome number was 2n = 76 in all 3 species, and NORs were observed in 2 chromosome pairs each. The microsatellite distribution pattern was similar in both Progne species, whereas P. cyanoleuca presented a distinct organization. These repetitive DNA sequences were found in the centromeric, pericentromeric, and telomeric regions of the macrochromosomes, as well as in 2 interstitial blocks in the W chromosome. Most microchromosomes had mainly telomeric signals. The Z chromosome displayed 1 hybridization signal in P. tapera but none in the other species. In contrast, the W chromosome showed an accumulation of different microsatellite sequences. The swallow W chromosome is larger than that of most Passeriformes. The observed enlargement in chromosome size might be explained by these high amounts of repetitive sequences. In sum, our data highlight the significant role that microsatellite sequences may play in sex chromosome differentiation.

scholarly journals Cretaceous diversity and disparity in a lacewing lineage of predators (Neuroptera: Mantispidae)

2020 ◽  
Vol 287 (1928) ◽  
pp. 20200629 ◽  
Author(s):  
Xiumei Lu ◽  
Bo Wang ◽  
Weiwei Zhang ◽  
Michael Ohl ◽  
Michael S. Engel ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Evolutionary History ◽  
Complete Loss ◽  
Remarkable Case ◽  
Predator Prey ◽  
Functional Convergence ◽  
The Family ◽  
High Species Diversity ◽  
History Of ◽  
Tropical Forest Ecosystem

Mantidflies (Mantispidae) are an unusual and charismatic group of predatory lacewings (Neuroptera), whereby the adults represent a remarkable case of morphological and functional convergence with praying mantises (Mantodea). The evolutionary history of mantidflies remains largely unknown due to a scarcity of fossils. Here, we report the discovery of a highly diverse palaeofauna of mantidflies from the mid-Cretaceous (lowermost Cenomanian) of Myanmar. The raptorial forelegs of these mantidflies possess highly divergent morphological modifications, some of which are unknown among modern mantidflies, e.g. the presence of forked basal profemoral spines or even the complete loss of foreleg spine-like structures. A phylogenetic analysis of Mantispidae reveals a pattern of raptorial foreleg evolution across the family. The high species diversity and disparate foreleg characters might have been driven by diverse niches of predator–prey interplay in the complex tropical forest ecosystem of the mid-Cretaceous.

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