scholarly journals The origins, scaling and loss of tetrapod digits

2017 ◽  
Vol 372 (1713) ◽  
pp. 20150482 ◽  
Author(s):  
Aditya Saxena ◽  
Matthew Towers ◽  
Kimberly L. Cooper
Keyword(s):  
Limb Development ◽  
Genome Engineering ◽  
Charles Darwin ◽  
Morphological Diversity ◽  
Supporting Evidence ◽  
Developmental Potential ◽  
Current State ◽  
Evolutionary Variation ◽  
Hands And Feet ◽  
Evo Devo

Many of the great morphologists of the nineteenth century marvelled at similarities between the limbs of diverse species, and Charles Darwin noted these homologies as significant supporting evidence for descent with modification from a common ancestor. Sir Richard Owen also took great care to highlight each of the elements of the forelimb and hindlimb in a multitude of species with focused attention on the homology between the hoof of the horse and the middle digit of man. The ensuing decades brought about a convergence of palaeontology, experimental embryology and molecular biology to lend further support to the homologies of tetrapod limbs and their developmental origins. However, for all that we now understand about the conserved mechanisms of limb development and the development of gross morphological disturbances, little of what is presented in the experimental or medical literature reflects the remarkable diversity resulting from the 450 million year experiment of natural selection. An understanding of conserved and divergent limb morphologies in this new age of genomics and genome engineering promises to reveal more of the developmental potential residing in all limbs and to unravel the mechanisms of evolutionary variation in limb size and shape. In this review, we present the current state of our rapidly advancing understanding of the evolutionary origin of hands and feet and highlight what is known about the mechanisms that shape diverse limbs. This article is part of the themed issue ‘Evo-devo in the genomics era, and the origins of morphological diversity’.

scholarly journals Origin of animal multicellularity: precursors, causes, consequences—the choanoflagellate/sponge transition, neurogenesis and the Cambrian explosion

2017 ◽  
Vol 372 (1713) ◽  
pp. 20150476 ◽  
Author(s):  
Thomas Cavalier-Smith
Keyword(s):  
Connective Tissue ◽  
Photosynthetic Bacteria ◽  
Cell Structure ◽  
Morphological Diversity ◽  
Cambrian Explosion ◽  
Feeding Modes ◽  
Selection For ◽  
Evo Devo ◽  
Gastraea Theory ◽  
Bacterial Food

Evolving multicellularity is easy, especially in phototrophs and osmotrophs whose multicells feed like unicells. Evolving animals was much harder and unique; probably only one pathway via benthic ‘zoophytes’ with pelagic ciliated larvae allowed trophic continuity from phagocytic protozoa to gut-endowed animals. Choanoflagellate protozoa produced sponges. Converting sponge flask cells mediating larval settling to synaptically controlled nematocysts arguably made Cnidaria. I replace Haeckel's gastraea theory by a sponge/coelenterate/bilaterian pathway: Placozoa, hydrozoan diploblasty and ctenophores were secondary; stem anthozoan developmental mutations arguably independently generated coelomate bilateria and ctenophores. I emphasize animal origin's conceptual aspects (selective, developmental) related to feeding modes, cell structure, phylogeny of related protozoa, sequence evidence, ecology and palaeontology. Epithelia and connective tissue could evolve only by compensating for dramatically lower feeding efficiency that differentiation into non-choanocytes entails. Consequentially, larger bodies enabled filtering more water for bacterial food and harbouring photosynthetic bacteria, together adding more food than cell differentiation sacrificed. A hypothetical presponge of sessile triploblastic sheets (connective tissue sandwiched between two choanocyte epithelia) evolved oogamy through selection for larger dispersive ciliated larvae to accelerate benthic trophic competence and overgrowing protozoan competitors. Extinct Vendozoa might be elaborations of this organismal grade with choanocyte-bearing epithelia, before poriferan water channels and cnidarian gut/nematocysts/synapses evolved. This article is part of the themed issue ‘Evo-devo in the genomics era, and the origins of morphological diversity’.

scholarly journals Major evolutionary transitions and innovations: the tympanic middle ear

2017 ◽  
Vol 372 (1713) ◽  
pp. 20150483 ◽  
Author(s):  
Abigail S. Tucker
Keyword(s):  
Middle Ear ◽  
Morphological Diversity ◽  
The Novel ◽  
Evolutionary Transitions ◽  
Jaw Joint ◽  
Evolution Of Mammals ◽  
Key Steps ◽  
Evo Devo ◽  
Relationship Of ◽  
The Relationship

One of the most amazing transitions and innovations during the evolution of mammals was the formation of a novel jaw joint and the incorporation of the original jaw joint into the middle ear to create the unique mammalian three bone/ossicle ear. In this review, we look at the key steps that led to this change and other unusual features of the middle ear and how developmental biology has been providing an understanding of the mechanisms involved. This starts with an overview of the tympanic (air-filled) middle ear, and how the ear drum (tympanic membrane) and the cavity itself form during development in amniotes. This is followed by an investigation of how the ear is connected to the pharynx and the relationship of the ear to the bony bulla in which it sits. Finally, the novel mammalian jaw joint and versatile dentary bone will be discussed with respect to evolution of the mammalian middle ear. This article is part of the themed issue ‘Evo-devo in the genomics era, and the origins of morphological diversity’.

scholarly journals Phylogenetic evidence for the modular evolution of metazoan signalling pathways

2017 ◽  
Vol 372 (1713) ◽  
pp. 20150477 ◽  
Author(s):  
Leslie S. Babonis ◽  
Mark Q. Martindale
Keyword(s):  
Cell Signalling ◽  
Large Body ◽  
Morphological Diversity ◽  
Signalling Pathway ◽  
Signalling Pathways ◽  
Special Focus ◽  
Tissue Interactions ◽  
Modular Evolution ◽  
Membrane Bound ◽  
Evo Devo

Communication among cells was paramount to the evolutionary increase in cell type diversity and, ultimately, the origin of large body size. Across the diversity of Metazoa, there are only few conserved cell signalling pathways known to orchestrate the complex cell and tissue interactions regulating development; thus, modification to these few pathways has been responsible for generating diversity during the evolution of animals. Here, we summarize evidence for the origin and putative function of the intracellular, membrane-bound and secreted components of seven metazoan cell signalling pathways with a special focus on early branching metazoans (ctenophores, poriferans, placozoans and cnidarians) and basal unikonts (amoebozoans, fungi, filastereans and choanoflagellates). We highlight the modular incorporation of intra- and extracellular components in each signalling pathway and suggest that increases in the complexity of the extracellular matrix may have further promoted the modulation of cell signalling during metazoan evolution. Most importantly, this updated view of metazoan signalling pathways highlights the need for explicit study of canonical signalling pathway components in taxa that do not operate a complete signalling pathway. Studies like these are critical for developing a deeper understanding of the evolution of cell signalling. This article is part of the themed issue ‘Evo-devo in the genomics era, and the origins of morphological diversity’.

scholarly journals A Novel Missense Variant of HOXD13 Caused Atypical Synpolydactyly by Impairing the Downstream Gene Expression and Literature Review for Genotype–Phenotype Correlations

2021 ◽  
Vol 12 ◽  
Author(s):  
Ruiji Guo ◽  
Xia Fang ◽  
Hailei Mao ◽  
Bin Sun ◽  
Jiateng Zhou ◽  
...  
Keyword(s):  
Limb Development ◽  
Missense Variant ◽  
Missense Mutations ◽  
Loss Of Function ◽  
Phenotype Correlation ◽  
Mutation Site ◽  
Genotype Phenotype Correlation ◽  
Α Helix ◽  
Severe Degree ◽  
Hands And Feet

Synpolydactyly (SPD) is a hereditary congenital limb malformation with distinct syndactyly designated as SPD1, SPD2, and SPD3. SPD1 is caused by mutations of HOXD13, which is a homeobox transcription factor crucial for limb development. More than 143 SPD patients have been reported to carry HOXD13 mutations, but there is a lack of genotype–phenotype correlation. We report a novel missense mutation of c. 925A > T (p.I309F) in an individual with atypical synpolydactyly inherited from her father with mild clinodactyly and three other different alanine insertion mutations in HOXD13 identified by whole exome sequencing (WES) in 12 Chinese SPD families. Unlike polyalanine extension, which tends to form α-helix and causes protein aggregation in the cytoplasm as shown by molecular simulation and immunofluorescence, the c. 925A > T mutation impairs downstream transcription of EPHA7. We compiled literature findings and analyzed genotype–phenotype features in 173 SPD individuals of 53 families, including 12 newly identified families. Among the HOXD13-related individuals, mutations were distributed in three regions: polyalanine, homeobox, and non-homeobox. Polyalanine extension was the most common variant (45%), followed by missense mutations (32%) mostly in the homeobox compared with the loss-of-function (LOF) variants more likely in non-homeobox. Furthermore, a more severe degree and classic SPD were associated with polyalanine mutations although missense variants were associated with brachydactyly and syndactyly in hands and feet and LOF variants with clinodactyly in hands. Our study broadens the HOXD13 mutation spectrum and reveals the profile of three different variants and their severity of SPD, the genotype–phenotype correlation related to the HOXD13 mutation site provides clinical insight, including for genetic counseling.

scholarly journals Se configura la segunda síntesis de la teoría evolutiva

2014 ◽  
Vol 1 (372) ◽  
pp. 21-35
Author(s):  
Oswaldo Báez Tobar
Keyword(s):  
Charles Darwin ◽  
Evo Devo ◽  
Siglo Xx

La teoría evolutiva es la teoría fundamental de la biología.  Se presentó  a la comunidad científica en dos pequeños ensayos sobre la evolución por selección natural  preparados en forma independiente por Charles Darwin y Alfred R. Wallace. Luego de la publicación del principal  libro de Darwin: El Origen de las Especies -que aporta numerosas pruebas y una amplia explicación de la teoría de la descendencia-, el pensamiento evolucionista  fue denominado: Darwinismo. Con el avance de las ciencias de la vida  a mediados del siglo XX  se  reformuló el darwinismo clásico  en un nuevo corpus: la Teoría Sintética de la Evolución o Neodarwinismo que se sustenta en  la genética mendeliana y la genética de poblaciones; sobre esta base  se construyó el pensamiento evolucionista moderno que tuvo vigencia plena en  casi todo el siglo pasado. Surgieron cuestionamientos en el seno del neodarwinismo que no pusieron  en duda la validez de la teoría de evolución por selección natural, pero que llevaron a incorporan otros factores explicativos de la transformación evolutiva, además de la selección.  En esa perspectiva se viene trabajando en las últimas décadas, al punto que se habla ya de una segunda síntesis de la teoría de evolución o Síntesis Expandida, que emerge del marco conceptual de la genética molecular, la genómica, la biología del desarrollo y  la ecología; razón por la cual a este nuevo paradigma se lo conoce también como Eco-Evo-Devo. Si la Teoría Sintética de la Evolución fue uno de avances mayores de las ciencias biológicas del siglo anterior, la segunda síntesis o Síntesis Expandida, se perfila como la construcción teórica más trascendental de la biología actual.

scholarly journals Darwin's Galápagos finches in modern biology

2010 ◽  
Vol 365 (1543) ◽  
pp. 1001-1007 ◽  
Author(s):  
Arhat Abzhanov
Keyword(s):  
Natural Selection ◽  
Evolutionary Biology ◽  
Charles Darwin ◽  
Niche Partitioning ◽  
Morphological Diversity ◽  
Theme Issue ◽  
Modern Biology ◽  
Wide Audience ◽  
Darwin's Finches ◽  
Darwin’S Finches

One of the classic examples of adaptive radiation under natural selection is the evolution of 15 closely related species of Darwin's finches (Passeriformes), whose primary diversity lies in the size and shape of their beaks. Since Charles Darwin and other members of the Beagle expedition collected these birds on the Galápagos Islands in 1835 and introduced them to science, they have been the subjects of intense research. Many biology textbooks use Darwin's finches to illustrate a variety of topics of evolutionary theory, such as speciation, natural selection and niche partitioning. Today, as this Theme Issue illustrates, Darwin's finches continue to be a very valuable source of biological discovery. Certain advantages of studying this group allow further breakthroughs in our understanding of changes in recent island biodiversity, mechanisms of speciation and hybridization, evolution of cognitive behaviours, principles of beak/jaw biomechanics as well as the underlying developmental genetic mechanisms in generating morphological diversity. Our objective was to bring together some of the key workers in the field of ecology and evolutionary biology who study Darwin's finches or whose studies were inspired by research on Darwin's finches. Insights provided by papers collected in this Theme Issue will be of interest to a wide audience.

scholarly journals Cavefish and the basis for eye loss

2017 ◽  
Vol 372 (1713) ◽  
pp. 20150487 ◽  
Author(s):  
Jaya Krishnan ◽  
Nicolas Rohner
Keyword(s):  
Embryonic Development ◽  
Convergent Evolution ◽  
Current Knowledge ◽  
Morphological Diversity ◽  
Astyanax Mexicanus ◽  
Genomic Resources ◽  
Evolutionary Forces ◽  
Different Populations ◽  
Entire World ◽  
Evo Devo

Animals have colonized the entire world from rather moderate to the harshest environments, some of these so extreme that only few animals are able to survive. Cave environments present such a challenge and obligate cave animals have adapted to perpetual darkness by evolving a multitude of traits. The most common and most studied cave characteristics are the regression of eyes and the overall reduction in pigmentation. Studying these traits can provide important insights into how evolutionary forces drive convergent and regressive adaptation. The blind Mexican cavefish ( Astyanax mexicanus ) has emerged as a useful model to study cave evolution owing to the availability of genetic and genomic resources, and the amenability of embryonic development as the different populations remain fertile with each other. In this review, we give an overview of our current knowledge underlying the process of regressive and convergent evolution using eye degeneration in cavefish as an example. This article is part of the themed issue ‘Evo-devo in the genomics era, and the origins of morphological diversity’.

scholarly journals New genes from old: asymmetric divergence of gene duplicates and the evolution of development

2017 ◽  
Vol 372 (1713) ◽  
pp. 20150480 ◽  
Author(s):  
Peter W. H. Holland ◽  
Ferdinand Marlétaz ◽  
Ignacio Maeso ◽  
Thomas L. Dunwell ◽  
Jordi Paps
Keyword(s):  
Gene Duplication ◽  
Homeobox Genes ◽  
Morphological Diversity ◽  
Gene Duplications ◽  
Tandem Gene Duplication ◽  
Sequence Change ◽  
New Genes ◽  
Gene Duplicates ◽  
Evo Devo ◽  
Animal Genomes

Gene duplications and gene losses have been frequent events in the evolution of animal genomes, with the balance between these two dynamic processes contributing to major differences in gene number between species. After gene duplication, it is common for both daughter genes to accumulate sequence change at approximately equal rates. In some cases, however, the accumulation of sequence change is highly uneven with one copy radically diverging from its paralogue. Such ‘asymmetric evolution’ seems commoner after tandem gene duplication than after whole-genome duplication, and can generate substantially novel genes. We describe examples of asymmetric evolution in duplicated homeobox genes of moths, molluscs and mammals, in each case generating new homeobox genes that were recruited to novel developmental roles. The prevalence of asymmetric divergence of gene duplicates has been underappreciated, in part, because the origin of highly divergent genes can be difficult to resolve using standard phylogenetic methods. This article is part of the themed issue ‘Evo-devo in the genomics era, and the origins of morphological diversity’.

scholarly journals Craniofacial development illuminates the evolution of nightbirds (Strisores)

2021 ◽  
Vol 288 (1948) ◽  
Author(s):  
Guillermo Navalón ◽  
Sergio M. Nebreda ◽  
Jen A. Bright ◽  
Matteo Fabbri ◽  
Roger B. J. Benson ◽  
...  
Keyword(s):  
Shape Change ◽  
Phenotypic Variability ◽  
Cranial Morphology ◽  
Skull Morphology ◽  
Bird Evolution ◽  
Ontogenetic Trajectory ◽  
Evolutionary Variation ◽  
Evo Devo ◽  
Shape Changes

Evolutionary variation in ontogeny played a central role in the origin of the avian skull. However, its influence in subsequent bird evolution is largely unexplored. We assess the links between ontogenetic and evolutionary variation of skull morphology in Strisores (nightbirds). Nightbirds span an exceptional range of ecologies, sizes, life-history traits and craniofacial morphologies constituting an ideal test for evo-devo hypotheses of avian craniofacial evolution. These morphologies include superficially ‘juvenile-like’ broad, flat skulls with short rostra and large orbits in swifts, nightjars and allied lineages, and the elongate, narrow rostra and globular skulls of hummingbirds. Here, we show that nightbird skulls undergo large ontogenetic shape changes that differ strongly from widespread avian patterns. While the superficially juvenile-like skull morphology of many adult nightbirds results from convergent evolution, rather than paedomorphosis, the divergent cranial morphology of hummingbirds originates from an evolutionary reversal to a more typical avian ontogenetic trajectory combined with accelerated ontogenetic shape change. Our findings underscore the evolutionary lability of cranial growth and development in birds, and the underappreciated role of this aspect of phenotypic variability in the macroevolutionary diversification of the amniote skull.

scholarly journals Perspectives on the history of evo-devo and the contemporary research landscape in the genomics era

2017 ◽  
Vol 372 (1713) ◽  
pp. 20150473 ◽  
Author(s):  
Cheryll Tickle ◽  
Araxi O. Urrutia
Keyword(s):  
Developmental Biology ◽  
Developmental Plasticity ◽  
Morphological Diversity ◽  
Evolutionary Developmental Biology ◽  
Major Transitions ◽  
History Of ◽  
Genetics And Genomics ◽  
Living Organisms ◽  
Evo Devo ◽  
Intraspecific Morphological Variation

A fundamental question in biology is how the extraordinary range of living organisms arose. In this theme issue, we celebrate how evolutionary studies on the origins of morphological diversity have changed over the past 350 years since the first publication of the Philosophical Transactions of The Royal Society . Current understanding of this topic is enriched by many disciplines, including anatomy, palaeontology, developmental biology, genetics and genomics. Development is central because it is the means by which genetic information of an organism is translated into morphology. The discovery of the genetic basis of development has revealed how changes in form can be inherited, leading to the emergence of the field known as evolutionary developmental biology (evo-devo). Recent approaches include imaging, quantitative morphometrics and, in particular, genomics, which brings a new dimension. Articles in this issue illustrate the contemporary evo-devo field by considering general principles emerging from genomics and how this and other approaches are applied to specific questions about the evolution of major transitions and innovations in morphology, diversification and modification of structures, intraspecific morphological variation and developmental plasticity. Current approaches enable a much broader range of organisms to be studied, thus building a better appreciation of the origins of morphological diversity. This article is part of the themed issue ‘Evo-devo in the genomics era, and the origins of morphological diversity’.

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