Tardigrades form a monophyletic group of microscopic ecdysozoans best known for
surviving extreme environmental conditions. Due to their key phylogenetic position as a …

Gene duplication generates new genetic material that can contribute to the evolution of gene
regulatory networks and phenotypes. Duplicated genes can undergo subfunctionalization to …

The nervous systems in most bilaterians are centralized, composed of central nervous
systems (CNS) and peripheral nervous systems (PNS). Common molecular and cellular …

Abstract Background Seisonidea (also Seisonacea or Seisonidae) is a group of small
animals living on marine crustaceans (Nebalia spec.) with only four species described so …

During early animal evolution, the emergence of axially polarized segments was central to
the diversification of complex bilaterian body plans. Nevertheless, precisely how and when …

Budd et al. challenge the identity of neural traces reported for the Cambrian lobopodian
Cardiodictyon catenulum. Their argumentation is unsupported, as are objections with …

Background Early during onychophoran development and prior to the formation of the germ
band, a posterior tissue thickening forms the posterior pit. Anterior to this thickening forms a …

The larval segment formation and secondary loss in echiurans is a special phenomenon,
which is considered to be one of the important characteristics in the evolutionary relationship …

Background Wnt genes code for ligands that activate signaling pathways during
development in Metazoa. Through the canonical Wnt (cWnt) signaling pathway, these genes …

Background Chaetognaths are a clade of marine worm-like invertebrates with a heavily
debated phylogenetic position. Their nervous system superficially resembles the protostome …