Placozoa Are Not Derived Cnidarians: Evidence from Molecular Morphology

Placozoa are not derived cnidarians: evidence from molecular morphology.

The phylum Placozoa is represented by a single known species, Trichoplax adhaerens, a tiny marine organism that represents the most simple metazoan bauplan. Because of the latter, placozoans were originally considered the most basal metazoan phylum. A misinterpretation of the life cycle at the turn of the century and some more recent molecular phylogenetic analyses have placed Trichoplax as a d...

Molecular signatures for sex in the Placozoa.

Placozoans, the simplest free-living animals, have never been observed to reproduce sexually. Here, we describe molecular evidence for sexual reproduction within one clade of the Placozoa. In a population sample of 10 individuals, within-individual and overall nucleotide diversity were similar to each other and consistent with levels observed in sexually reproducing species. Intergenic recombin...

Molecular Morphology - Phylogenetically Informative Characters Derived from Sequence Data Dissertation

A fundamental problem in biology is the reconstruction of the relatedness of all (extant) species. Traditionally, systematists employ visually recognizable characters of organisms for classification and evolutionary analysis. Recent developments in molecular and computational biology, however, lead to a whole different perspective on how to address the problem of inferring relatedness. The disc...

Further evidence that enterochromaffin cells are not derived from the neural crest.

SUMMARY Recently, a previous finding that the enterochromaffin cells of chick embryos are not derived from the neural crest has been contested, and so further evidence has been sought. Presumptive gut, i.e. endoderm and adherent mesoderm, of embryos between the short head-process stage and the 25-somite stage was grown on the chorio-allantoic membranes of host embryos. Whether the presumptive g...

Transcriptomic evidence that enigmatic parasites Polypodium hydriforme and Myxozoa are cnidarians