Divergent Uses of “Parallel Evolution” during the History of The American Naturalist

2019 ◽  
Vol 193 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Yoel E. Stuart
Genetics ◽  
1998 ◽  
Vol 150 (2) ◽  
pp. 807-814
Author(s):  
Adalgisa Caccone ◽  
Gi-Sik Min ◽  
Jeffrey R Powell

Abstract For more than 60 years, evolutionary cytogeneticists have been using naturally occurring chromosomal inversions to infer phylogenetic histories, especially in insects with polytene chromosomes. The validity of this method is predicated on the assumption that inversions arise only once in the history of a lineage, so that sharing a particular inversion implies shared common ancestry. This assumption of monophyly has been generally validated by independent data. We present the first clear evidence that naturally occurring inversions, identical at the level of light microscopic examination of polytene chromosomes, may not always be monophyletic. The evidence comes from DNA sequence analyses of regions within or very near the breakpoints of an inversion called the 2La that is found in the Anopheles gambiae complex. Two species, A. merus and A. arabiensis, which are fixed for the “same” inversion, do not cluster with each other in a phylogenetic analysis of the DNA sequences within the 2La. Rather, A. merus 2La is most closely related to strains of A. gambiae homozygous for the 2L+. A. gambiae and A. merus are sister taxa, the immediate ancestor was evidently homozygous 2L+, and A. merus became fixed for an inversion cytologically identical to that in A. arabiensis. A. gambiae is polymorphic for 2La/2L+, and the 2La in this species is nearly identical at the DNA level to that in A. arabiensis, consistent with the growing evidence that introgression has or is occurring between these two most important vectors of malaria in the world. The parallel evolution of the “same” inversion may be promoted by the presence of selectively important genes within the breakpoints.


1993 ◽  
Vol 6 (2) ◽  
pp. 111 ◽  
Author(s):  
RS Hill ◽  
GJ Jordan

A cladistic analysis of Nothofagus is presented. Comparison of potential outgroups (Fagus and Betulaceae) suggests that Fagus is most satisfactory, but clear morphological differences between it and Nothofagus support the placement of the latter in the monogeneric family Nothofagaceae. The cladistic analysis supports the four subgenera and four extant pollen groups proposed in the most recent revisions and is consistent with the extensive fossil record, although not especially supported by it. The evolution of the deciduous or evergreen habit. so long considered a singular event of importance in Nothofagus, probably occurred several times, and is an example of parallel evolution. Resolution within subgenera is not high in most cases, but subgenus Lophozonia offers a particularly interesting insight into the relationship among extant species and the role of rare long distance dispersal across significant ocean barriers in Nothofagus biogeography. More data are required to refine the phylogeny.


1969 ◽  
Vol 68 (6) ◽  
pp. 123-170 ◽  
Author(s):  
Roger S. Miles

SynopsisThe initial adaptive radiation of the Placodermi took place rapidly following the development of the basic placoderm adaptive complex after the ancestral scale covering of the trunk fused into a rigid shield, and not long before the group appears in the fossil record in the Lower Devonian. The radiation was mainly concerned with different ways of living in the benthos of a variety of marine and fresh-water environments; a few nektonic species appear late in the history of the Arthrodira. The fossil record shows the evolution of the orders in their adaptive zones. The zones become increasingly distinct as the orders evolve and become more specific in their adaptations, and the arthrodire, antiarch and rhenanid zones segregate into successively occupied sub-zones. The evolution of the Placodermi has been previously described in terms of improvements in the locomotor mechanism by an analysis of changes in the trunk-armour and pectoral fins. A more detailed description can be given by considering the feeding mechanism as well; this is particularly true of the largest order, the Arthrodira. Study of the feeding mechanism involves the cervical joints as well as the jaws and gnathals. The cervical joints had the same functions in feeding as the anterior part of the vertebral column (“the neck”) in many higher fish. In arthrodires jaw action involved vertical movements of the mandibular lever; the upper jaw apparatus is comparable to the rigid palatoquadrate-maxillary complex of primitive bony fish. The mandible was transformed into a bent lever inBrachyosteusby the development of a small “coronoid” process, but the arthrodire jaw apparatus remained undeveloped in comparison with Actinopterygii and Elasmobranchii. Arthrodire jaw suspension was autostylic. Evidence from the Rhenanida and Ptyctodontida has been interpreted to suggest that this condition was secondary, and that primitive placoderms had an elasmobranch or holocephalan-like palatoquadrate with hyostylic suspension. This view is not entirely supported by the state of the palatoquadrate in primitive arthrodires, but there is no good evidence that placoderms had a complete, open spiracular gill-slit (the aphethoyoid condition). Arthrodire phylogeny cannot yet be described in vertical lines, but four successive levels of organization of increasing efficiency can be recognized; the actinolepid, phlyctaenaspid, coccosteomorph and pachyosteomorph levels. These levels can be defined by simple characters relating to broad adaptations in the locomotor and feeding mechanisms. Evolutionary trends in the Arthrodira include the enlargement of the scapulocoracoid and base of the pectoral fin and the reduction of the spinal plate and flank armour, as the fish gain better control in the water and more myomeres become available for use in swimming; and the enlargement of the nuchal gap and development of the cranio-thoracic joint as powerful muscles are developed to raise the head to give a wide gape, accompanied by the specialization of the gnathals for different modes of feeding. Some of these trends are reversed in compressed, nektonic species. The description of arthrodire phylogeny in terms of changes that can be understood from a functional point of view reveals interesting examples of mosaic and parallel evolution.Parabelosteusn.gen. is erected.


1993 ◽  
Vol 71 (3) ◽  
pp. 515-523 ◽  
Author(s):  
J. D. McPhail

Pairs of plankton-feeding and benthos-foraging sticklebacks (Gasterosteus aculeatus) (limnetics and benthics) coexist in six small lakes in southwestern British Columbia. In spite of a persistent low level of hybridization the pairs maintain themselves as distinct genetic and ecological entities; because of this they are viewed as biological species. They appear to be restricted to the central Strait of Georgia region, and the geological history of the area argues that they are of postglacial origin. The pairs occur on three islands (Vancouver, Texada, and Lasqueti), but even on these islands they are not found in all available lakes. Both lake morphometry (size and depth) and altitude appear to influence local distribution. Hypotheses that might explain the origin of the pairs are examined. Neither theory nor data support a sympatric origin, but an allopatric origin through two invasions of marine sticklebacks is consistent with both the geological history of the area and the details of local distribution. An independent but parallel evolution of the pairs on at least two islands (Vancouver and Texada) is implicit in this hypothesis. The hypothesis also assumes that although the initial divergence started in allopatry, competitive interactions in sympatry played a major role in the evolution of reproductive isolation and resource partitioning.


PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2333 ◽  
Author(s):  
Jian-Cheng Wang ◽  
Bo-Rong Pan ◽  
Dirk C. Albach

Perennials and annuals apply different strategies to adapt to the adverse environment, based on ‘tolerance’ and ‘avoidance’, respectively. To understand lifespan evolution and its impact on plant adaptability, we carried out a comparative study of perennials and annuals in the genusVeronicafrom a phylogenetic perspective. The results showed that ancestors of the genusVeronicawere likely to be perennial plants. Annual life history ofVeronicahas evolved multiple times and subtrees with more annual species have a higher substitution rate. Annuals can adapt to more xeric habitats than perennials. This indicates that annuals are more drought-resistant than their perennial relatives. Due to adaptation to similar selective pressures, parallel evolution occurs in morphological characters among annual species ofVeronica.


Author(s):  
Pedro Martínez ◽  
Volker Hartenstein ◽  
Simon G. Sprecher

The emergence and diversification of bilateral animals are among the most important transitions in the history of life on our planet. A proper understanding of the evolutionary process will derive from answering such key questions as, how did complex body plans arise in evolutionary time, and how are complex body plans “encoded” in the genome? the first step is focusing on the earliest stages in bilaterian evolution, probing the most elusive organization of the genomes and microscopic anatomy in basally branching taxa, which are currently assembled in a clade named Xenacoelomorpha. This enigmatic phylum is composed of three major taxa: acoel flatworms, nemertodermatids, and xenoturbellids. Interestingly, the constituent species of this clade have an enormously varied set of morphologies; not just the obvious external features but also their tissues present a high degree of constructional variation. This interesting diversity of morphologies (a clear example being the nervous system, with animals showing different degrees of compaction) provides a unique system in which to address outstanding questions regarding the parallel evolution of genomes and the many morphological characters encoded by them. A systematic exploration of the anatomy of members of these three taxa, employing immunohistochemistry, in situ hybridization, and high-throughput transmission electron microscopy, will provide the reference framework necessary to understand the changing roles of genes and gene networks during the evolution of xenacoelomorph morphologies and, in particular, of their nervous systems.


Author(s):  
Jussi M. Hanhimäki

Pax Transatlantica asserts that the recurrent transatlantic crises that have dominated headlines since the end of the Cold War, while not irrelevant, pale when set against the realities of shared interests and goals. It emphasizes three key factors. First, despite inflammatory and dismissive rhetoric, NATO continues to provide a solid security structure for its member states: an institutional framework of a Pax Transatlantica that has stood the test of time by expanding its remit and scope. Second, in a world concerned with the potential effects of trade wars (especially between the United States and China) and the rise of economic nationalism, the transatlantic economic relationship stands apart as the richest, most closely integrated transcontinental economic space on the globe. Third, the book traces the parallel evolution of domestic politics on both sides of the Atlantic with specific focus on the rise of populism. Rather than a sign of transatlantic “drift,” the rise of populism—much like the emergence of so-called Third Way politics on both sides of the Atlantic in the 1990s—is evidence of a closely integrated transatlantic political space. In the end, while it is obvious that the history of the transatlantic relationship—even during the Cold War—was littered with crises, the relationship has endured. Conflicts have illustrated, time and again, the strength of the transatlantic community. The “West,” the book concludes, not only continues to exist. It is likely to thrive in the future.


2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Vicente Pérez-Brocal ◽  
Rosario Gil ◽  
Andrés Moya ◽  
Amparo Latorre

Since the establishment of the symbiosis between the ancestor of modern aphids and their primary endosymbiont, Buchnera aphidicola, insects and bacteria have coevolved. Due to this parallel evolution, the analysis of bacterial genomic features constitutes a useful tool to understand their evolutionary history. Here we report, based on data from B. aphidicola, the molecular evolutionary analysis, the phylogenetic relationships among lineages and a comparison of sequence evolutionary rates of symbionts of four aphid species from three subfamilies. Our results support previous hypotheses of divergence of B. aphidicola and their host lineages during the early Cretaceous and indicate a closer relationship between subfamilies Eriosomatinae and Lachninae than with the Aphidinae. They also reveal a general evolutionary pattern among strains at the functional level. We also point out the effect of lifecycle and generation time as a possible explanation for the accelerated rate in B. aphidicola from the Lachninae.


1968 ◽  
Vol 46 (6) ◽  
pp. 741-749 ◽  
Author(s):  
Bernard R. Baum

The main steps in the history of delimitation of Medicago and Trigonella are given. The typical medicagos have been characterized by spirally coiled pods; the typical trigonellas, by cylindrical straight or curved pods. The cause of the long disagreement is due to the existence of species having flattened or compressed pods in both genera. Such species were considered by most botanists to be intermediate between Trigonella and Medicago. Some botanists included all these species in Medicago whereas others included them in Trigonella. Some proposed an intermediate genus, e.g. Pocockia, Melissitus. In 1873, Urban suggested the characters of the cotyledons as the only reliable criteria for delimitation between the two genera. New evidence based on floral characters supports Urban's generic concept. A possible parallel evolution of pod shape is assumed to have occurred in both genera.


Author(s):  
Maddie E. James ◽  
Henry Arenas-Castro ◽  
Jeffery S. Groh ◽  
Jan Engelstädter ◽  
Daniel Ortiz-Barrientos

AbstractParallel evolution of ecotypes occurs when selection independently drives the evolution of similar traits across similar environments. The multiple origin of ecotypes is often inferred on the basis of a phylogeny which clusters populations according to geographic location and not by the environment they occupy. However, the use of phylogenies to infer parallel evolution in closely related populations is problematic due to the potential for gene flow and incomplete lineage sorting to uncouple the genetic structure at neutral markers from the colonization history of populations. Here, we demonstrate multiple origins within ecotypes of an Australian wildflower, Senecio lautus. We observed strong genetic structure as well as phylogenetic clustering by geography, and show this is unlikely due to gene flow between parapatric ecotypes, which is surprisingly low. We further confirm this analytically by demonstrating that phylogenetic distortion due to gene flow often requires higher levels of migration than those observed in S. lautus. Our results imply that selection can repeatedly create similar phenotypes despite the perceived homogenizing effects of gene flow.


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