A major goal of evolutionary biology is to understand the origins of phenotypic diversity. Changes in development, for instance heterochrony, can be a potent source of phenotypic variation. On the other hand, ...
Authors: Kara E. Powder, Kayla Milch, Garrett Asselin and R. Craig Albertson
Gastrulation is a critical step in bilaterian development, directly linked to the segregation of germ layers, establishment of axes, and emergence of the through-gut. Theories about the evolution of gastrulati...
Authors: Deirdre C. Lyons, Kimberly J. Perry and Jonathan Q. Henry
The metagenesis of sessile polyps into pelagic medusae in cnidarians represents one of the most ancient complex life cycles in animals. Interestingly, scyphozoans and hydrozoans generate medusae by apparently ...
Authors: Johanna E. M. Kraus, David Fredman, Wei Wang, Konstantin Khalturin and Ulrich Technau
Siphonophores (Hydrozoa) have unparalleled colony-level complexity, precision of colony organization, and functional specialization between zooids (i.e., the units that make up colonies). Previous work has sho...
Authors: Stefan Siebert, Freya E. Goetz, Samuel H. Church, Pathikrit Bhattacharyya, Felipe Zapata, Steven H.D. Haddock and Casey W. Dunn
Vertebrate somites are subdivided into lineage compartments, each with distinct cell fates and evolutionary histories. Insights into somite evolution can come from studying amphioxus, the best extant approxima...
Authors: Jennifer H Mansfield, Edward Haller, Nicholas D Holland and Ava E Brent
The evolutionary origins of cell polarity in metazoan embryos are unclear. In most bilaterian animals, embryonic and cell polarity are set up during embryogenesis with the same molecules being utilized to regu...
Authors: Miguel Salinas-Saavedra, Thomas Q Stephenson, Casey W Dunn and Mark Q Martindale
Most of our current findings on appendage formation and patterning stem from studies on chordate and ecdysozoan model organisms. However, in order to fully understand the evolution of animal appendages, it is ...
Authors: Marie-Therese Nödl, Sara M Fossati, Pedro Domingues, Francisco J Sánchez and Letizia Zullo
Retinoic acid (RA) signaling controls many developmental processes in chordates, from early axis specification to late organogenesis. The functions of RA are chiefly mediated by a subfamily of nuclear hormone ...
Authors: Florent Campo-Paysaa, David Jandzik, Yoko Takio-Ogawa, Maria V Cattell, Haley C Neef, James A Langeland, Shigeru Kuratani, Daniel M Medeiros, Sylvie Mazan, Shigehiro Kuraku, Vincent Laudet and Michael Schubert
Wnt signaling is one of the earliest and most highly conserved regulatory pathways for the establishment of the body axes during regeneration and early development. In regeneration, body axes determination occ...
Authors: Alessandro Di Maio, Leah Setar, Stefano Tiozzo and Anthony W De Tomaso
Transcription factors that determine retinal development seem to be conserved in different phyla throughout the animal kingdom. In most representatives, however, only a few of the involved transcription factor...
Authors: Leyli Samadi, Axel Schmid and Bo Joakim Eriksson
Two visual systems are present in most arthropod groups: median and lateral eyes. Most of our current knowledge about the developmental and molecular mechanisms involved in eye formation in arthropods comes fr...
Authors: Christoph Schomburg, Natascha Turetzek, Magdalena Ines Schacht, Julia Schneider, Phillipp Kirfel, Nikola-Michael Prpic and Nico Posnien
How adaptive phenotypes are shaped by the action of key developmental genes during ontogeny remains poorly understood. Water striders, a group of hemipteran insects, present a unique example of adaptation to l...
The molecular mechanisms underlying sex determination and differentiation in animals are incredibly diverse. The Dmrt (doublesex and mab-3 related transcription factor) gene family is an evolutionary ancient grou...
Authors: Nikki G Traylor-Knowles, Eric G Kane, Vanna Sombatsaphay, John R Finnerty and Adam M Reitzel
The tardigrades (water bears) are a cosmopolitan group of microscopic ecdysozoans found in a variety of aquatic and temporarily wet environments. They are members of the Panarthropoda (Tardigrada + Onychophora...
Simple life cycles arise from complex life cycles when one or more developmental stages are lost. This raises a fundamental question - how can an intermediate stage, such as a larva, be removed, and developmen...
Authors: Rebecca R Helm, Stefano Tiozzo, Martin K S Lilley, Fabien Lombard and Casey W Dunn
Brachiopods undergo radial cleavage, which is distinct from the stereotyped development of closely related spiralian taxa. The mesoderm has been inferred to derive from the archenteron walls following gastrula...
Authors: Yale J Passamaneck, Andreas Hejnol and Mark Q Martindale
The urodele amphibians (salamanders) are the only adult tetrapods able to regenerate the limb. It is unclear if this is an ancestral property that is retained in salamanders but lost in other tetrapods or if i...
Authors: Jie Geng, Phillip B Gates, Anoop Kumar, Stefan Guenther, Acely Garza-Garcia, Carsten Kuenne, Peng Zhang, Mario Looso and Jeremy P Brockes
The limb and autopodium are frequently employed to study pattern formation during embryonic development, providing insights into how cells give rise to complex anatomical structures. With regard to the differe...
Authors: Eraqi R Khannoon, Anthony P Russell and Abigail S Tucker
The ABC model of flower development describes the molecular basis for specification of floral organ identity in model eudicots such as Arabidopsis and Antirrhinum. According to this model, expression of C-class g...
Authors: Ana Maria R Almeida, Roxana Yockteng, Wagner C Otoni and Chelsea D Specht
The bat has strikingly divergent forelimbs (long digits supporting wing membranes) and hindlimbs (short, typically free digits) due to the distinct requirements of both aerial and terrestrial locomotion. Durin...
Authors: Mandy K Mason, Dorit Hockman, Lyle Curry, Thomas J Cunningham, Gregg Duester, Malcolm Logan, David S Jacobs and Nicola Illing
Within Malacostraca (Crustacea), direct development and development through diverse forms of larvae are found. Recent investigations suggest that larva-related developmental features have undergone heterochron...
Authors: Günther Joseph Jirikowski, Carsten Wolff and Stefan Richter
Nodal is an important determinant of the left-right (LR) body axis in bilaterians, specifying the right side in protostomes and non-chordate deuterostomes as opposed to the left side in chordates. Amphioxus re...
Authors: Vladimir Soukup, Luok Wen Yong, Tsai-Ming Lu, Song-Wei Huang, Zbynek Kozmik and Jr-Kai Yu
The form that an animal takes during development is directed by gene regulatory networks (GRNs). Developmental GRNs interpret maternally deposited molecules and externally supplied signals to direct cell-fate ...
Authors: Alys M Cheatle Jarvela and Veronica F Hinman
The cellular signaling mechanisms and morphogenic movements involved in axis formation and gastrulation are well conserved between vertebrates. In nearly all described fish, gastrulation and the initial patter...
Ctenophores have traditionally been treated as eumetazoans, but some recent whole genome studies have revived the idea that they are, rather, the sister group to all other metazoans. This deep branching positi...
Authors: Gáspár Jékely, Jordi Paps and Claus Nielsen
The Solenogastres (or Neomeniomorpha) are a taxon of aplacophoran molluscs with contentious phylogenetic placement. Since available developmental data on non-conchiferan (that is, aculiferan) molluscs mainly s...
Authors: Emanuel Redl, Maik Scherholz, Christiane Todt, Tim Wollesen and Andreas Wanninger
The independent origin and evolution of leaves as small, simple microphylls or larger, more complex megaphylls in plants has shaped and influenced the natural composition of the environment. Significant contri...
Two issues relating to the translocation of anterior Hox genes in echinoderms to the 5’ end of the Hox cluster are discussed: i) that developmental changes associated with fixation to the substratum have led to a...
Seahorses are well known for their highly derived head shape, prehensile tail and armoured body. They belong to the family of teleosts known as Syngnathidae, which also includes the pipefishes, pipehorses and ...
Authors: Tamara Anne Franz-Odendaal and Dominique Adriaens
Hox genes are master regulatory genes that specify positional identities during axial development in animals. Discoveries regarding their concerted expression patterns have commanded intense interest due to th...
Authors: Sophie Archambeault, Julia Ann Taylor and Karen D Crow
Developmental biology, as all experimental science, is empowered by technological advances. The availability of genetic tools in some species - designated as model organisms - has driven their use as major pla...
Lepidium sisymbrioides, a polyploid New Zealand endemic, is the sole dioecious species in Brassicaceae and therefore the closest dioecious relative of the model plant Arabidopsis thaliana. The attractiveness of d...
Authors: Valerie L Soza, Vietnam Le Huynh and Verónica S Di Stilio
Among the Lophotrochozoa, cephalopods possess the highest degree of central nervous system (CNS) centralization and complexity. Although the anatomy of the developing cephalopod CNS has been investigated, the ...
Authors: Tim Wollesen, Carmel McDougall, Bernard M Degnan and Andreas Wanninger
Understanding the molecular basis of craniofacial variation can provide insights into key developmental mechanisms of adaptive changes and their role in trophic divergence and speciation. Arctic charr (Salvelinus...
Authors: Ehsan Pashay Ahi, Kalina Hristova Kapralova, Arnar Pálsson, Valerie Helene Maier, Jóhannes Gudbrandsson, Sigurdur S Snorrason, Zophonías O Jónsson and Sigrídur Rut Franzdóttir
Metazoan digestive systems develop from derivatives of ectoderm, endoderm and mesoderm, and vary in the relative contribution of each germ layer across taxa and between gut regions. In a small number of well-s...
Authors: Michael J Boyle, Emi Yamaguchi and Elaine C Seaver
Insect embryonic dorso-ventral patterning depends greatly on two pathways: the Toll pathway and the Bone Morphogenetic Protein pathway. While the relative contribution of each pathway has been investigated in ...
Authors: Mateus Berni, Marcio Ribeiro Fontenele, Vitoria Tobias-Santos, Aline Caceres-Rodrigues, Flavia Borges Mury, Raquel Vionette-do-Amaral, Hatisaburo Masuda, Marcos Sorgine, Rodrigo Nunes da Fonseca and Helena Araujo
Proseriates (Proseriata, Platyhelminthes) are free-living, mostly marine, flatworms measuring at most a few millimetres. In common with many flatworms, they are known to be capable of regeneration; however, fe...
Authors: Johannes Girstmair, Raimund Schnegg, Maximilian J Telford and Bernhard Egger
Although chordates descend from a segmented ancestor, the evolution of head segmentation has been very controversial for over 150 years. Chordates generally possess a segmented pharynx, but even though anatomi...
Authors: Demian Koop, Jie Chen, Maria Theodosiou, João E Carvalho, Susana Alvarez, Angel R de Lera, Linda Z Holland and Michael Schubert
Enhanced food-finding efficiency is an obvious adaptive response to cave environments. Here, we have compared the food-finding abilities of Astyanax surface fish and blind cavefish young larvae in their first mon...
Authors: Luis Espinasa, Jonathan Bibliowicz, William R Jeffery and Sylvie Rétaux
Multicellularity provides organisms with opportunities for cell-type specialization, but requires novel mechanisms to position correct proportions of different cell types throughout the organism. Dictyostelid ...
Authors: Christina Schilde, Anna Skiba and Pauline Schaap
Mammals exhibit a remarkable variety of phenotypes and comparative studies using novel model species are needed to uncover the evolutionary developmental mechanisms generating this diversity. Here, we undertak...
Authors: Sophie A Montandon, Athanasia C Tzika, António F Martins, Bastien Chopard and Michel C Milinkovitch
Annual killifishes inhabit temporary ponds and their embryos survive the dry season encased in the mud by entering diapause, a process that arrests embryonic development during hostile conditions. Annual killi...
Authors: Luca Dolfi, Roberto Ripa and Alessandro Cellerino
During development, juvenile nematodes undergo four molts. Although the number of molts appears to be constant within the Nematoda, the timing of the first molt can occur either before or after hatching. A pre...
Cellular differentiation is a critical process during development of multicellular animals that must be tightly controlled in order to avoid precocious differentiation or failed generation of differentiated ce...
The Hes superfamily or Hes/Hey-related genes encompass a variety of metazoan-specific bHLH genes, with somewhat fuzzy phylogenetic relationships. Hes superfamily members are involved in a variety of major develop...
Authors: Eve Gazave, Aurélien Guillou and Guillaume Balavoine
The teleost Astyanax mexicanus is a single species consisting of eyed surface-dwelling (surface fish) and blind cave-dwelling (cavefish) morphs. Cavefish eyes are lost through apoptosis of the lens, which in turn...
Authors: Li Ma, Amy Parkhurst and William R Jeffery
Disentangling evolutionary shifts in developmental timing (heterochony) is dependent upon accurate estimates of ancestral patterns. However, many classic assessments of heterochronic patterns predate robust ph...
Authors: Ronald M Bonett, Michael A Steffen and Grant A Robison
The primary hormone of the vertebrate pineal gland, melatonin, has been identified broadly throughout the eukaryotes. While the role for melatonin in cyclic behavior via interactions with the circadian clock h...
Authors: Rafael Peres, Adam M Reitzel, Yale Passamaneck, Solange Castro Afeche, José Cipolla-Neto, Antonio Carlos Marques and Mark Q Martindale
A particularly critical event in avian evolution was the transition from long- to short-tailed birds. Primitive bird tails underwent significant alteration, most notably reduction of the number of caudal verte...
Authors: Dana J Rashid, Susan C Chapman, Hans CE Larsson, Chris L Organ, Anne-Gaelle Bebin, Christa S Merzdorf, Roger Bradley and John R Horner
Segmentation is a feature of the body plans of a number of diverse animal groupings, including the annelids, arthropods and chordates. However, it has been unclear whether or not these different manifestations...
Authors: Anthony Graham, Thomas Butts, Andrew Lumsden and Clemens Kiecker
