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| Open AccessThe cichlid oral and pharyngeal jaws are evolutionarily and genetically coupled
Modular, rather than integrated systems are classically thought to allow functional diversity to evolve rapidly. A study of cichlid fish shows integration between divergent jaw systems at the phylogenetic, population, and genetic scales, suggesting integration can and does facilitate rapid, coordinated trait evolution.
- Andrew J. Conith
- & R. Craig Albertson
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Article
| Open AccessExites in Cambrian arthropods and homology of arthropod limb branches
The common ancestor of all living arthropods had biramous postantennal appendages, with an endopodite and exopodite branching off the limb base. This study uses microtomographic imaging of the Cambrian arthropod Leanchoilia to reveal a previously undetected exite at the base of most appendages, suggesting a deeper origin for exites in arthropod phylogeny.
- Yu Liu
- , Gregory D. Edgecombe
- & Xianguang Hou
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Article
| Open AccessEarly-life social experience affects offspring DNA methylation and later life stress phenotype
Early social experience can alter epigenetic patterns and stress responses later in life. A study on wild spotted hyenas finds that maternal care and social connections after leaving the den influence DNA methylation and contribute to a developmentally plastic stress response.
- Zachary M. Laubach
- , Julia R. Greenberg
- & Wei Perng
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Article
| Open AccessThe evolution of convex trade-offs enables the transition towards multicellularity
Multicellularity is a major evolutionary transition that remains poorly characterized at the ecological and genetic level. Exposing unicellular green algae to a rotifer predator showed that just 500 generations of predator selection were sufficient to lead to a convex trade-off and incorporate evolved changes into the prey genome.
- Joana P. Bernardes
- , Uwe John
- & Lutz Becks
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Article
| Open AccessCnidarian-bilaterian comparison reveals the ancestral regulatory logic of the β-catenin dependent axial patterning
The authors show in Nematostella that the more orally expressed β-catenin targets repress the more aborally expressed β-catenin targets, thus patterning the oral-aboral axis. This likely represents the common mechanism of β-catenin-dependent axial patterning shared by Cnidaria and Bilateria.
- Tatiana Lebedeva
- , Andrew J. Aman
- & Grigory Genikhovich
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Article
| Open AccessCretaceous bird with dinosaur skull sheds light on avian cranial evolution
In addition to major innovations in their locomotor system, early birds evolved highly derived skulls. Here, Wang et al. three dimensionally reconstruct the skull of a new enantiornithine bird from the Early Cretaceous that illustrates the early avialan transitions in skull morphology and function.
- Min Wang
- , Thomas A. Stidham
- & Zhonghe Zhou
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Article
| Open AccessHox dosage contributes to flight appendage morphology in Drosophila
Here, the authors show that the Hox genes Antennapedia (Antp) and Ultrabithorax (Ubx) control flight appendage morphology in Drosophila. This role is dependent on a particular spatial expression profile and dosage, which was also found in evolutionary distant four-winged insect species.
- Rachel Paul
- , Guillaume Giraud
- & Samir Merabet
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Article
| Open AccessSize, microhabitat, and loss of larval feeding drive cranial diversification in frogs
The evolution of metamorphic species may be constrained by different ecologies of the larval and adult stages. Here, Bardua et al. show that in frogs, adult ecology is more important than larval ecology for skull evolution, but species that don’t feed as tadpoles evolve faster than those that do.
- Carla Bardua
- , Anne-Claire Fabre
- & Anjali Goswami
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Article
| Open AccessExceptionally preserved early Cambrian bilaterian developmental stages from Mongolia
The Cambrian is known as a period of rapid animal diversification, but the development of these animals is not well characterized. Here, Steiner et al. describe a new assemblage of Cambrian eggs, embryos and early postembryonic stages from Mongolia that provides insight into ancient bilaterian development and evolution.
- Michael Steiner
- , Ben Yang
- & Philip Donoghue
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Article
| Open AccessDynamic sex chromosome expression in Drosophila male germ cells
Sex chromosome gene content and expression is unusual. Here the authors use single cell RNA-Seq on Drosophila larvae to demonstrate that the single X and pair of 4th chromosomes are specifically inactivated in primary spermatocytes, while genes on the single Y chromosome become maximally active in primary spermatocytes.
- Sharvani Mahadevaraju
- , Justin M. Fear
- & Brian Oliver
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Article
| Open AccessLarge-scale genome sequencing of mycorrhizal fungi provides insights into the early evolution of symbiotic traits
Mycorrhizal symbioses have evolved repeatedly in diverse fungal lineages. A large phylogenomic analysis sheds light on genomic changes associated with transitions from saprotrophy to symbiosis, including divergent genetic innovations underlying the convergent origins of the ectomycorrhizal guild.
- Shingo Miyauchi
- , Enikő Kiss
- & Francis M. Martin
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Article
| Open AccessIntegrin-alpha-6+ Candidate stem cells are responsible for whole body regeneration in the invertebrate chordate Botrylloides diegensis
Clonal ascidians are able to undergo whole body regeneration (WBR), where entire new bodies can be regenerated from blood vessel fragments. Here, the authors provide evidence in Botrylloides diegensis supporting pou3 and vasa expressing blood-borne cells isolated with anti-IA6 antibody as candidate stem cells responsible for WBR.
- Susannah H. Kassmer
- , Adam D. Langenbacher
- & Anthony W. De Tomaso
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Article
| Open AccessGenes with spiralian-specific protein motifs are expressed in spiralian ciliary bands
Spiralians have ciliary bands, used for locomotion and feeding, but defining molecular features of these structures are unknown. Here, the authors report a gene, Lophotrochin, that contains a protein domain only found in spiralians, and specifically expressed in diverse ciliary bands across the group, which provides a molecular signature for these structures.
- Longjun Wu
- , Laurel S. Hiebert
- & J. David Lambert
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Article
| Open AccessTurning induced plasticity into refined adaptations during range expansion
Phenotypic robustness to environmental variation is seemingly at odds with evolvability. Here, the authors analyze carotenoid use and accommodation in feather development across a recent avian range expansion and show that cooption of a stress-buffering mechanism can reconcile robustness and evolvability.
- Ahva L. Potticary
- , Erin S. Morrison
- & Alexander V. Badyaev
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Article
| Open AccessJellyfish genomes reveal distinct homeobox gene clusters and conservation of small RNA processing
Jellyfish plays an important ecological role in surface waters and the deep sea. Here the authors report genome sequences of two true jellyfish, Sanderia malayensis and Rhopilema esculentum, showing distinct homeobox gene clusters and sesquiterpenoid pathway.
- Wenyan Nong
- , Jianquan Cao
- & Jerome H. L. Hui
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Article
| Open AccessA hypomorphic cystathionine ß-synthase gene contributes to cavefish eye loss by disrupting optic vasculature
The teleost Astyanax mexicanus has sighted morphs living in surface rivers and various blind morphs living in caves. Here, the authors suggest that loss of eyes in cave morphs is linked to mutations in the cystathionine ß-synthase a (cbsa) gene, which cause eye degeneration by disrupting function of the optic circulatory system.
- Li Ma
- , Aniket V. Gore
- & William R. Jeffery
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Article
| Open AccessGenomic adaptations to aquatic and aerial life in mayflies and the origin of insect wings
Genomic studies of paleopteran insects, such as mayflies, are needed to reconstruct early insect evolution. Here, Almudi and colleagues present the genome of the mayfly Cloeon dipterum and use transcriptomics to characterize its adaptations to distinct habitats and the origin of insect wings.
- Isabel Almudi
- , Joel Vizueta
- & Fernando Casares
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Article
| Open AccessEcology and allometry predict the evolution of avian developmental durations
Developmental duration is a key life-history trait. Cooney et al. compile data on 3096 bird species to quantify the degree to which phylogenetic history, body size and ecological variables like predation risk or breeding phenology influence variation in developmental duration.
- Christopher R. Cooney
- , Catherine Sheard
- & Alison E. Wright
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| Open AccessEarly Jurassic dinosaur fetal dental development and its significance for the evolution of sauropod dentition
Dinosaurs had some of the most complex dentitions known. Here, Reisz et al. characterize dental development across embryonic, hatchling and adult Lufengosaurus, an Early Jurassic sauropodomorph dinosaur, and suggest that derived sauropod dentition evolved by paedomorphosis (juvenilization).
- Robert R. Reisz
- , Aaron R. H. LeBlanc
- & Shiming Zhong
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Article
| Open AccessThe morphology, molecular development and ecological function of pseudonectaries on Nigella damascena (Ranunculaceae) petals
Interspecies interactions, including those between plants and pollinators, can involve deception. The authors characterize the molecular development of Nigella damascena pseudonectaries, and their adaptive function in attracting specific pollinators to concealed nectaries with visual cues.
- Hong Liao
- , Xuehao Fu
- & Hongzhi Kong
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Article
| Open AccessDifferential DNA methylation of vocal and facial anatomy genes in modern humans
How traits specific to modern humans have evolved is difficult to study. Here, Gokhman et al. compare measured and reconstructed DNA methylation maps of present-day humans, archaic humans and chimpanzees and find that genes that affect vocal tract and facial anatomy show methylation changes between archaic and modern humans.
- David Gokhman
- , Malka Nissim-Rafinia
- & Liran Carmel
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Article
| Open AccessNeo-functionalization of a Teosinte branched 1 homologue mediates adaptations of upland rice
A transposon insertion in the regulatory region of maize Tb1 gene leads to increased apical dominance and a reduction of tillering. Here, the authors showed that a duplicated rice Tb1 orthologue, OsTb2, has gained a regulatory effect on tillering opposite that of OsTb1 during artificial selection only in upland japonica rice.
- Jun Lyu
- , Liyu Huang
- & Fengyi Hu
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Article
| Open AccessA transposable element insertion is associated with an alternative life history strategy
Tradeoffs are central to life history theory and evolutionary biology, yet almost nothing is known about their mechanistic basis. Here the authors characterize one such mechanism and find a transposable element insertion is associated with the switch between alternative life history strategies.
- Alyssa Woronik
- , Kalle Tunström
- & Christopher W. Wheat
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Article
| Open AccessComparative analysis of squamate brains unveils multi-level variation in cerebellar architecture associated with locomotor specialization
The cerebellum is critical in sensory-motor control and is structurally diverse across vertebrates. Here, the authors investigate the evolutionary relationship between locomotory mode and cerebellum architecture across squamates by integrating study of gene expression, cell distribution, and 3D morphology.
- Simone Macrì
- , Yoland Savriama
- & Nicolas Di-Poï
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Article
| Open AccessFoxg specifies sensory neurons in the anterior neural plate border of the ascidian embryo
Vertebrate telencephalon formation requires Foxg-Fgf8 cross-regulation, but while ascidians express Foxg in the neural plate, they lack a telencephalon. Here the authors show that Foxg loss does not affect ascidian brain formation, indicating that telencephalon evolution required recruitment of Fgf downstream of Foxg.
- Boqi Liu
- & Yutaka Satou
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Article
| Open AccessA genome-wide assessment of the ancestral neural crest gene regulatory network
An understanding of the ancestral state of the neural crest (NC) gene regulatory network (GRN) gives insight into vertebrate evolution. Here, the authors use transcriptomic and chromatin accessibility analyses of the lamprey NC, as well as cross-species enhancer assays, to identify GRN elements conserved throughout vertebrates.
- Dorit Hockman
- , Vanessa Chong-Morrison
- & Tatjana Sauka-Spengler
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Article
| Open AccessA conserved regulatory program initiates lateral plate mesoderm emergence across chordates
Numerous tissues are derived from the lateral plate mesoderm (LPM) but how this is specified is unclear. Here, the authors identify a pan-LPM reporter activity found in the zebrafish draculin (drl) gene that also shows transgenic activity in LPM-corresponding territories of several chordates, including chicken, axolotl, lamprey, Ciona, and amphioxus.
- Karin D. Prummel
- , Christopher Hess
- & Christian Mosimann
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Article
| Open AccessEvolutionary modification of AGS protein contributes to formation of micromeres in sea urchins
Micromeres in a sea urchin embryo are formed by asymetric cleavage but what molecular mechanisms regulate their formation is unclear. Here, the authors show that sea urchins modify an evolutionarily conserved AGS-dependent mechanism to induce asymmetric cell divisions in the early embryo.
- Jessica Poon
- , Annaliese Fries
- & Mamiko Yajima
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Article
| Open AccessEvidence against tetrapod-wide digit identities and for a limited frame shift in bird wings
The homology of digits across amniotes is debated. Here, the authors compare the developmental transcriptomes of digits across five divergent amniotes and show high evolutionary dynamism in expression profiles, with conservation of a distinct developmental identity only in the anterior-most digit.
- Thomas A. Stewart
- , Cong Liang
- & Günter P. Wagner
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Article
| Open AccessA Hox-TALE regulatory circuit for neural crest patterning is conserved across vertebrates
Mechanisms coupling Hox genes to neural crest are largely unknown. Here, the authors use cross species regulatory comparisons between the Hox2 genes of jawed vertebrates and lamprey, a jawless vertebrate, finding a conserved ancestral mechanism for Hox2 neural crest regulation.
- Hugo J. Parker
- , Bony De Kumar
- & Robb Krumlauf
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Article
| Open AccessInverse resource allocation between vision and olfaction across the genus Drosophila
Neural architecture may be shaped by selection, but is likely also constrained by development. Here, Keesey and colleagues find an inverse relationship between allocation towards visual and olfactory sensory systems across the genus Drosophila, which may reflect a developmental trade-off.
- Ian W. Keesey
- , Veit Grabe
- & Bill S. Hansson
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Article
| Open AccessAn evolutionarily-conserved Wnt3/β-catenin/Sp5 feedback loop restricts head organizer activity in Hydra
Hydra regenerate various body parts on amputation by activation of the appropriate organiser, but how head formation is controlled is unclear. Here, the authors identify the transcription factor Sp5 as restricting head formation, by being activated by beta-catenin and then acting as a repressor of Wnt3.
- Matthias C. Vogg
- , Leonardo Beccari
- & Brigitte Galliot
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Article
| Open AccessTranscription factor DUO1 generated by neo-functionalization is associated with evolution of sperm differentiation in plants
The evolutionary mechanisms leading to the development of sperm are poorly understood. Here, the authors infer that neofunctionalisation and expression changes of the orthologue of DUO1 in algal ancestors of land plants were key events for sperm differentiation and sexual reproduction in this lineage.
- Asuka Higo
- , Tomokazu Kawashima
- & Takashi Araki
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Article
| Open AccessPhenotype loss is associated with widespread divergence of the gene regulatory landscape in evolution
Cis-regulatory elements are important factors for morphological changes. Here, the authors show widespread divergence of limb and eye regulatory elements in limb loss in snakes and eye degeneration in subterranean mammals respectively.
- Juliana G. Roscito
- , Katrin Sameith
- & Michael Hiller
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Article
| Open AccessA sulfotransferase dosage-dependently regulates mouthpart polyphenism in the nematode Pristionchus pacificus
Certain genotypes define developmental plasticity and discrete morphologies, but a mechanism as to how this arises is unclear. Here, the authors show that dosage-specific sulfotransferase (SEUD-1) expression specifies which mouthparts are expressed in the nematode Pristionchus pacificus, dependent on the environment.
- Linh T. Bui
- , Nicholas A. Ivers
- & Erik J. Ragsdale
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Article
| Open AccessRepeated inversions within a pannier intron drive diversification of intraspecific colour patterns of ladybird beetles
The harlequin ladybird beetle, Harmonia axyridis, has remarkable phenotypic diversity, with over 200 colour patterns. Here, Ando et al. show that this patterning is regulated by the transcription factor gene pannier and has diversified by repeated inversions and cis-regulatory modifications of pannier.
- Toshiya Ando
- , Takeshi Matsuda
- & Teruyuki Niimi
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Article
| Open AccessConservation of epigenetic regulation by the MLL3/4 tumour suppressor in planarian pluripotent stem cells
The Mll3/4 histone methyltransferases can act as tumour suppressors in humans. Here, the authors identify three orthologs of mammalian MLL3/4 in the planarian Schmidtea mediterranea and show that knockdown causes outgrowths in regenerating animals, suggesting that the tumour suppressive function of these genes is deeply conserved.
- Yuliana Mihaylova
- , Prasad Abnave
- & A. Aziz Aboobaker
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Article
| Open AccessSensing of cytosolic LPS through caspy2 pyrin domain mediates noncanonical inflammasome activation in zebrafish
In humans, caspase-5 is an LPS sensor that can induce gasdermin D cleavage and pyroptosis. Here, the authors show that zebrafish caspy2 is a functional homolog as it also senses cytosolic LPS to activate the noncanonical inflammasome and to protect against bacterial infection, but it does so via pyrin death domain interactions.
- Dahai Yang
- , Xin Zheng
- & Qin Liu
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Article
| Open AccessLarge-scale gene losses underlie the genome evolution of parasitic plant Cuscuta australis
Dodders (Cuscuta spp., Convolvulaceae) are root- and leafless parasitic plants. Here, the authors sequence the genome of Cuscuta australis and find remarkable gene loss associated with parasitic lifestyle and large changes in body plan.
- Guiling Sun
- , Yuxing Xu
- & Jianqiang Wu
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Comment
| Open AccessMaking head or tail of cnidarian hox gene function
Hox genes are known to regulate head-tail axis patterning but their molecular role in animals diverged from the bilaterian lineage is unclear. Here, Fabian Rentzsch and Thomas W. Holstein comment on a paper by Mark Martindale and colleagues on the functional role of two Hox genes in axial patterning of the sea anemone.
- Fabian Rentzsch
- & Thomas W. Holstein
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Article
| Open AccessHox and Wnt pattern the primary body axis of an anthozoan cnidarian before gastrulation
Hox genes regulate anterior–posterior axis formation but their role in cnidarians is unclear. Here, the authors disrupt Hox genes NvAx1 and NvAx6 in the starlet sea anemone, Nematostella vectensis, showing antagonist function in patterning the oral–aboral axis and a link to Wnt signaling.
- Timothy Q. DuBuc
- , Thomas B. Stephenson
- & Mark Q. Martindale
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Article
| Open AccessAID/APOBEC-like cytidine deaminases are ancient innate immune mediators in invertebrates
The AID/APOBEC cytidine deaminase family are nucleic acid editors, important for antigen receptor expression and thought to have evolved along with vertebrate adaptive immunity. Here the authors show this family may have evolved prior to adaptive immunity as members with cytidine deaminase activity are present and functional in invertebrate sea urchins and brachiopods.
- Mei-Chen Liu
- , Wen-Yun Liao
- & Sebastian D. Fugmann
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Article
| Open AccessReconstruction of the ancestral metazoan genome reveals an increase in genomic novelty
Animals, the Metazoa, co-opted numerous unicellular genes in their transition to multicellularity. Here, the authors use phylogenomic analyses to infer the genome composition of the ancestor of extant animals and show there was also a burst of novel gene groups associated with this transition.
- Jordi Paps
- & Peter W. H. Holland
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Article
| Open AccessManipulation of insulin signaling phenocopies evolution of a host-associated polyphenism
The red-shouldered soapberry bug, Jadera haematoloma, is a potential model system for developmental plasticity. Here, the authors show that the reaction norm for wing polyphenism has evolved in a recently derived ecotype and identify insulin signaling as a candidate pathway underlying this adaptive change.
- Meghan M. Fawcett
- , Mary C. Parks
- & David R. Angelini
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Article
| Open AccessBrain and eyes of Kerygmachela reveal protocerebral ancestry of the panarthropod head
The arthropod head is complex and its evolution has been difficult to reconstruct. Here, Park et al. describe new specimens of the Cambrian stem-group euarthropod Kerygmachela that preserve evidence of primitive compound eyes and a unipartite brain, providing insight into the structure of the early arthropod head.
- Tae-Yoon S. Park
- , Ji-Hoon Kihm
- & Jakob Vinther
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Article
| Open AccessA diminutive perinate European Enantiornithes reveals an asynchronous ossification pattern in early birds
Fossil juvenile Mesozoic birds are exceedingly rare and can provide important insight into the early evolution of avian development. Here, Knoll et al. describe one of the smallest known Mesozoic avians, which indicates a clade-wide asynchronous pattern of osteogenesis and great variation in basal bird hatchling size and skeletal maturation tempo.
- Fabien Knoll
- , Luis M. Chiappe
- & Jose Luis Sanz
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Article
| Open AccessThe ecological origins of snakes as revealed by skull evolution
Three alternatives have been proposed for the ecological state of the ancestral snake: fossorial (burrowing), aquatic, or terrestrial. Here, the authors use an integrative geometric morphometric approach that suggests evolution from terrestrial to fossorial in the most recent common ancestor of extant snakes.
- Filipe O. Da Silva
- , Anne-Claire Fabre
- & Nicolas Di-Poï
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Article
| Open AccessDevelopmental nonlinearity drives phenotypic robustness
Developmental processes often involve nonlinearities, but the consequences for translating genotype to phenotype are not well characterized. Here, Green et al. vary Fgf8 signaling across allelic series of mice and show that phenotypic robustness in craniofacial shape is explained by a nonlinear effect of Fgf8 expression.
- Rebecca M. Green
- , Jennifer L. Fish
- & Benedikt Hallgrímsson
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Article
| Open AccessEvolutionary recruitment of flexible Esrp-dependent splicing programs into diverse embryonic morphogenetic processes
Epithelial-mesenchymal interplays are essential to many ontogenetic processes in vertebrates. Here Burguera et al. show diverse embryonic morphogenetic processes regulated by Epithelial Splicing Regulatory Protein (Esrp) in different deuterostome species.
- Demian Burguera
- , Yamile Marquez
- & Manuel Irimia