2017/10/12 by Michael Eitel, Warren R. Francis, Hans‐Jürgen Osigus +6 · 7 citations
Biochemistry, Genetics and Molecular Biology · Earth and Planetary Sciences · Environmental Science · #Biology #Chordate #Evolutionary biology #Gene #Genetics #Genome #Genus #Identification and Quantification in Food #Lineage (genetic) #Marine Invertebrate Physiology and Ecology #Parasite Biology and Host Interactions #Phylum #Zoology
paper · pdf · doi:10.1101/202119
published in bioRxiv (Cold Spring Harbor Laboratory) (Cold Spring Harbor Laboratory)
openalex publication_date 2017/10/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract The Placozoa [1] is a monotypic phylum of non-bilaterian marine animals. Its only species, Trichoplax adhaerens , was described in 1883 [2], Despite the worldwide distribution of placozoans [3–6], morphological differences are lacking among isolates from different geographic areas and, consequently, no other species in this phylum has been described and accepted for more than 130 years. However, recent single-gene studies on the genetic diversity of this “species” have revealed deeply divergent lineages of, as yet, undefined taxonomic ranks [3,5,6], Since single genes are not considered sufficient to define species [7], a whole nuclear genome comparison appears the most appropriate approach to determine relationships between placozoan lineages. Such a “taxogenomics” approach can help discover and diagnose potential additional species and, therefore, develop a much-needed, more robust, taxonomic framework for this phylum. To achieve this we sequenced the genome of a placozoan lineage isolated from Hong Kong (lineage H13), which is distantly related to T. adhaerens [6]. The 87 megabase genome assembly contains 12,010 genes. Comparison to the T. adhaerens genome [8] identified an average protein distance of 24.4% in more than 2,700 screened one-to-one orthologs, similar to levels observed between the chordate classes mammals and birds. Genome rearrangements are commonplace and >25% of genes are not collinear (i.e. they are not in the same order in the two genomes). Finally, a multi-gene distance comparison with other non-bilaterian phyla indicate genus level differences to T. adhaerens . These data highlight the large genomic diversity within the Placozoa and justifies the designation of lineage HI3 as a new species, Xxxxxxxxx yyyyyyyyyyyyy 1 gen. et spaec. nov., now the second described placozoan species and the first in a new genus. Phylogenomic analyses furthermore supports a robust placement of the Placozoa as sister to a cnidarian-bilaterian clade.