The return of typology-Do turtles exemplify saltational evolution?

2017 ◽  
Vol 99 (3) ◽  
pp. 319-320
Author(s):  
Rainer R. Schoch
Keyword(s):  
Saltational Evolution

The rotated-lamina syndrome. VII. Direct formation of lamina in the rotated position in Pterospermum (Sterculiaceae) and the appearance of hyper-rotation

1997 ◽  
Vol 75 (1) ◽  
pp. 188-206 ◽  
Author(s):  
W. A. Charlton
Keyword(s):  
Normal Form ◽  
Shoot Apex ◽  
Leaf Development ◽  
Extreme Case ◽  
Lower Side ◽  
Symmetrical Form ◽  
Direct Formation ◽  
Saltational Evolution ◽  
Unidentified Species ◽  
Mode Of Development

The genus Pterospermum presents an extreme case of lamina rotation in their dorsiventral distichous shoots. In Pterospermum suberifolium and an unidentified species, the young laminae emerge from the bud with their upper surfaces facing towards the upper side of the shoot, and, in this, they resemble most other cases of lamina rotation. In Pterospermum heterophyllum and Pterospermum acerifolium, the lamina emerge in hyper-rotated orientation, with the upper surface of the lamina facing outwards away from the parent axis in P. heterophyllum or outwards and towards the lower side of the shoot in P. acerifolium. The early development of the lamina is unusual in all cases, since it appears to arise directly in the rotated position. This unusual mode of lamina development appears to be a case of saltational evolution. In P. acerifolium and P. heterophyllum, the leaf buttress also develops asymmetrically in the manner of other lamina rotators previously described, so that the lamina is rotated further with the formation of a triangular axillary site. This may be a relic of a more "normal" form of lamina rotation. Shoots with spiral phyllotaxis also occur in P. acerifolium, and in P. heterophyllum to a lesser extent, and these shoots have palmately lobed peltate leaves in contrast with the simple leaves of the dorsiventral shoots. The laminae in these shoots arise in a peculiar orientation, so that the upper surface of the lamina faces in the direction of growth of the shoot and never faces towards the shoot apex on which it formed. The mode of early lamina development in the spiral shoots is very similar to that of the dorsiventral shoots, but in the spiral shoots, the lamina is symmetrically placed instead of facing to one side of the shoot. It is suggested that the peculiar orientation of the lamina in the dorsiventral shoots arose first, and then a symmetrical form of this mode of development became incorporated into the leaves of the spiral shoots. Key words: Sterculiaceae, leaf, development, dorsiventrality, lamina rotation, hyper-rotation.

scholarly journals Saltational evolution of the heterotrimeric G protein signaling mechanisms in the plant kingdom

2016 ◽  
Vol 9 (446) ◽  
pp. ra93-ra93 ◽  
Author(s):  
Daisuke Urano ◽  
Natsumi Maruta ◽  
Yuri Trusov ◽  
Richard Stoian ◽  
Qingyu Wu ◽  
...  
Keyword(s):  
G Protein ◽  
G Protein Signaling ◽  
Protein Signaling ◽  
Heterotrimeric G Protein ◽  
Plant Kingdom ◽  
Signaling Mechanisms ◽  
Saltational Evolution ◽  
Heterotrimeric G Protein Signaling

scholarly journals On the feasibility of saltational evolution

2018 ◽  
Author(s):  
Mikhail I. Katsnelson ◽  
Yuri I. Wolf ◽  
Eugene V. Koonin
Keyword(s):  
Evolutionary Biology ◽  
Fitness Landscape ◽  
Evolutionary Process ◽  
Analytic Solutions ◽  
Population Bottlenecks ◽  
Effective Population ◽  
Evolutionary Transitions ◽  
Evolutionary Changes ◽  
Saltational Evolution ◽  
As Stress

One of the key tenets of Darwin’s theory that was inherited by the Modern Synthesis of evolutionary biology is gradualism, that is, the notion that evolution proceeds gradually, via accumulation of “infinitesimally small” heritable changes 1,2. However, some of the most consequential evolutionary changes, such as, for example, the emergence of major taxa, seem to occur abruptly rather than gradually, as captured in the concepts of punctuated equilibrium 3,4 and evolutionary transitions 5,6. We examine a mathematical model of an evolutionary process on a rugged fitness landscape 7,8 and obtain analytic solutions for the probability of multi-mutational leaps, that is, several mutations occurring simultaneously, within a single generation in one genome, and being fixed all together in the evolving population. The results indicate that, for typical, empirically observed combinations of the parameters of the evolutionary process, namely, effective population size, mutation rate, and distribution of selection coefficients of mutations, the probability of a multi-mutational leap is low, and accordingly, their contribution to the evolutionary process is minor at best. However, such leaps could become an important factor of evolution in situations of population bottlenecks and elevated mutation rates, such as stress-induced mutagenesis in microbes or tumor progression, as well as major evolutionary transitions and evolution of primordial replicators.

Saltational evolution of contact sex pheromone compounds of Callosobruchus rhodesianus (Pic)

Chemoecology ◽  
2015 ◽  
Vol 26 (1) ◽  
pp. 15-23 ◽  
Author(s):  
Kenji Shimomura ◽  
Shinpei Matsui ◽  
Kanju Ohsawa ◽  
Shunsuke Yajima
Keyword(s):  
Sex Pheromone ◽  
Contact Sex Pheromone ◽  
Callosobruchus Rhodesianus ◽  
Saltational Evolution

scholarly journals Biological Systematics in the Evo-Devo era

2015 ◽  
Author(s):  
Alessandro Minelli
Keyword(s):  
Phylogenetic Signal ◽  
Evolutionary Developmental Biology ◽  
Morphological Data ◽  
Spatial And Temporal Patterns ◽  
Saltational Evolution ◽  
Biological Systematics ◽  
Developmental Modulation ◽  
Evo Devo ◽  
Whole Life Cycle ◽  
Sympatric Morphs

Evolutionary developmental biology (evo-devo) suggests a distinction between modular and systemic variation. In the case of modular change, the conservation of the overall structure helps recognizing affinities, while a single, fast evolving module is likely to produce a bonanza for the taxonomist, while systemic changes produce strongly deviating morphologies that cause problems in tracing homologies. Similarly, changes affecting the whole life cycle are more challenging than those limited to one stage. Developmental modularity is a precondition for heterochrony. Analyzing a matrix of morphological data for paedomorphic taxa requires special care. It is, however, possible to extract phylogenetic signal from heterochronic patterns. The taxonomist should pay attention to the intricacies of the genotype→phenotype map. When using genetic data to infer phylogeny, a comparison of gene sequences is just a first step. To bridge the gap between genes and morphology we should consider the spatial and temporal patterns of gene expression, and their regulation. Minor genetic change can have major phenotypic effects, sometimes suggesting saltational evolution. Evo-devo is also relevant in respect to speciation: changes in developmental schedules are often implicated in the divergence between sympatric morphs, and a developmental modulation of ‘temporal phenotypes’ appears to be responsible for many cases of speciation.

scholarly journals The Emergence of Bacterial “Hopeful Monsters”

mBio ◽  
2014 ◽  
Vol 5 (4) ◽  
Author(s):  
Nicholas J. Croucher ◽  
Keith P. Klugman
Keyword(s):  
Pathogenic Bacteria ◽  
Full Range ◽  
Sequence Type ◽  
Resistant Bacteria ◽  
Antibiotic Resistant ◽  
Common Cause ◽  
Content Type ◽  
Global Spread ◽  
Health Care Associated Infections ◽  
Saltational Evolution

ABSTRACT The global spread of antibiotic-resistant bacteria has largely been driven by the dissemination of successful lineages. A particularly important example is sequence type (ST) 258 of Klebsiella pneumoniae, a common cause of health care-associated infections. Representatives of this lineage carry a variable array of plasmid-borne resistance genes, typically including a carbapenemase effective against the full range of clinically important β-lactams. In their recent mBio article, Chen et al. [mBio 5(3):e01355-14] described how ST258 emerged through “hybridization” between two other strains, with a second recombination resulting in the diversification of a key antigen. This commentary describes the findings in the context of other examples where saltational evolution has resulted in the sudden emergence of important pathogenic bacteria.

Saltational evolution of trunk segment number in centipedes

2009 ◽  
Vol 11 (3) ◽  
pp. 318-322 ◽  
Author(s):  
Alessandro Minelli ◽  
Amazonas Chagas-Júnior ◽  
Gregory D. Edgecombe
Keyword(s):  
Segment Number ◽  
Trunk Segment ◽  
Saltational Evolution
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