There is no highly conserved embryonic stage in the vertebrates: implications for current theories of evolution and development

  title={There is no highly conserved embryonic stage in the vertebrates: implications for current theories of evolution and development},
  author={Michael K. Richardson and James Hanken and Mayoni L. Gooneratne and Claude Pieau and Albert Raynaud and Lynne Selwood and Glenda M. Wright},
  journal={Anatomy and Embryology},
Abstract Embryos of different species of vertebrate share a common organisation and often look similar. [] Key Result We find that embryos at the tailbud stage – thought to correspond to a conserved stage – show variations in form due to allometry, heterochrony, and differences in body plan and somite number. These variations foreshadow important differences in adult body form.
The vertebrate phylotypic stage and an early bilaterian-related stage in mouse embryogenesis defined by genomic information
The results demonstrate that the mid-embryonic stage of the mouse is indeed highly constrained, supporting the existence of the phylotypic stage and highlighting the hierarchical aspect of embryogenesis proposed by von Baer.
Vertebrate evolution: the developmental origins of adult variation.
  • M. Richardson
  • Biology
    BioEssays : news and reviews in molecular, cellular and developmental biology
  • 1999
It is argued here that differences in adult morphology may be generated at a variety of stages, and the phylotypic stage, the developmental hourglass, modularity, and von Baerian divergence are reassessed in terms of these arguments.
Embryonic lethality is not sufficient to explain hourglass-like conservation of vertebrate embryos
The results suggest that negative selection by embryonic lethality could not explain hourglass-like conservation of animal embryos, and highlights the potential contribution of alternative mechanisms such as the diversifying effect of positive selections against earlier and later stages, and developmental constraints which lead to conservation of mid-embryonic stages.
Ontogeny and phylogeny of the yolk extension in embryonic cypriniform fishes.
It appears that yolk extension ontogenesis is a novel evolutionary, developmental module that has been incorporated into the phylotypic period of certain teleostean lineages.
Comparative methods in developmental biology.
It is clear that the application of phylogenetic methodology to developmental data is both necessary and fundamental to research into the relationship between evolution and development.
Haeckel's ABC of evolution and development
Haeckel's work is re‐examine and he is seen as the father of a sequence‐based phylogenetic embryology, and his embryo drawings are important as phylogenetic hypotheses, teaching aids, and evidence for evolution.
Comparative Transcriptomics Reveals Distinct Patterns of Gene Expression Conservation through Vertebrate Embryogenesis
A phylogenetic comparative approach is used to characterize expression conservation pattern of each gene at each evolutionary node across vertebrates and finds an enrichment of genes exhibiting early conservation, hourglass, late conservation patterns and a large depletion of gene exhibiting no distinguishable pattern of conservation in both microarray and RNA-seq data sets.
Inverting the hourglass: quantitative evidence against the phylotypic stage in vertebrate development
It is hypothesize that numerous tightly delimited developmental modules exist during the mid–embryonic period and the high level of timing changes between these modules may be an important evolutionary mechanism giving rise to the diversity of vertebrates.
In search of the vertebrate phylotypic stage: a molecular examination of the developmental hourglass model and von Baer's third law.
The molecular results suggest, albeit weakly, that a phylotypic stage (or period) indeed exists and its temporal location, sometimes between the first-somites stage and the formation of the posterior neuropore, was in approximate agreement with the morphologically defined phylotypesic stage.


Heterochrony and the phylotypic period.
The morphological data relating to developmental timing in somite-stage embryos are reexamined and reveal striking patterns of heterochrony during vertebrate evolution.
Hox genes and the evolution of vertebrate axial morphology.
A comparative study of the developmental patterns of homeobox gene expression and developmental morphology between animals that have homologous regulatory genes but different morphologies, which contributes a mechanistic level to the assumed homology of these regions in vertebrates.
Evolution of developmental decisions and morphogenesis: the view from two camps.
  • R. Raff
  • Biology
    Development (Cambridge, England). Supplement
  • 1992
Analysis of the complementary uses of the resulting data in the two fields as they grope for accommodation shows that what have been thought to be constrained mechanisms of axial determination, cell lineage patterning, and gastrulation in fact evolve readily and provide the means for the rapid evolution of development.
Stages of embryonic development of the zebrafish
A series of stages for development of the embryo of the zebrafish, Danio (Brachydanio) rerio is described, providing for flexibility and continued evolution of the staging series as the authors learn more about development in this species.
Morphogenetic Movements and Fate Maps of Vertebrates
Experimental results on the chondrostean sturgeon Acipenser are compared and contrasted with those on Salmo and Xenopus, showing in new elaborate detail how close the early development of AcIPenser is to that of modern amphibia, closer to Xenopus than to Rana , closer to anura than to urodeles.
Early cranial neural crest migration in the direct-developing frog, Eleutherodactylus coqui.
If observed evolutionary changes in embryonic cranial patterning are mediated by the neural crest, then they likely involve later aspects of crest migration or more subtle features related to pattern formation such as cell behavior and commitment, or gene expression.
Evolution of Avian Ontogenies
Compared purpose, avian hatchlings are described with reference to their external appearance, motor activity, locomotion patterns, feeding Behavior, capability of endothermy, parental feeding behavior, parental attendance, and developmental stage of tissue maturation, for example, natal down, sense organs, muscle, and brain.
Organization and Development of the Embryo
  • T. Lentz
  • History
    The Yale Journal of Biology and Medicine
  • 1970
Organization and Development of the Embryo is based on a series of Silliman Lectures at Yale University given by Ross G. Harrison in 1949 under the same title. Professor Harrison was unable to
Pigment pattern expression in the plumage of the quail embryo and the quail-chick chimaera
It is shown that neither differential migration nor differential proliferation is involved in pattern formation in the quail-chick chimaera, and local cues may be important in determining crest-cell differentiation.
Facial and visceral arch development in the mouse embryo: a study by scanning electron microscopy.
The morphogenesis of the face and visceral arch region were studied by scanning electron microscopy in 63 mouse embryos between 8 and 13 days post coitum and the temporal changes in shape and the interrelationships of the structures mentioned are described in detail.