Animal Evolution and the Molecular Signature of Radiations Compressed in Time

Rokas, Antonis; Krüger, Dirk; Carroll, Sean B.

doi:10.1126/science.1116759

Cited by 351 publications

(203 citation statements)

References 41 publications

(21 reference statements)

Supporting

Mentioning

193

Contrasting

Unclassified

Order By: Relevance

“…Rokas et al (2005) argued that metazoan diversification was compressed in time pointing out that, whereas fungal relationships are clearly resolved by the analysis of a large number of protein-coding genes, those of some metazoans are not. Because both groups evolved at around the same time, they reasoned that the early history of metazoans may have been a radiation compressed in time, in agreement with a direct reading of the palaeontological record.…”

Section: When Did Deuterostome Groups Originate?mentioning

confidence: 99%

Deciphering deuterostome phylogeny: molecular, morphological and palaeontological perspectives

Swalla

Smith

2008

Phil. Trans. R. Soc. B

223

219

View full text Add to dashboard Cite

Deuterostomes are a monophyletic group of animals that include the vertebrates, invertebrate chordates, ambulacrarians and xenoturbellids. Fossil representatives from most major deuterostome groups, including some phylum-level crown groups, are found in the Lower Cambrian, suggesting that evolutionary divergence occurred in the Late Precambrian, in agreement with some molecular clock estimates. Molecular phylogenies, larval morphology and the adult heart/kidney complex all support echinoderms and hemichordates as a sister grouping (Ambulacraria). Xenoturbellids are a relatively newly discovered phylum of worm-like deuterostomes that lacks a fossil record, but molecular evidence suggests that these animals are a sister group to the Ambulacraria. Within the chordates, cephalochordates share large stretches of chromosomal synteny with the vertebrates, have a complete Hox complex and are sister group to the vertebrates based on ribosomal and mitochondrial gene evidence. In contrast, tunicates have a highly derived adult body plan and are sister group to the vertebrates based on the analyses of concatenated genomic sequences. Cephalochordates and hemichordates share gill slits and an acellular cartilage, suggesting that the ancestral deuterostome also shared these features. Gene network data suggest that the deuterostome ancestor had an anterior-posterior body axis specified by Hox and Wnt genes, a dorsoventral axis specified by a BMP/chordin gradient, and was bilaterally symmetrical with left-right asymmetry determined by expression of nodal.

show abstract

Section: When Did Deuterostome Groups Originate?mentioning

confidence: 99%

Deciphering deuterostome phylogeny: molecular, morphological and palaeontological perspectives

Swalla

Smith

2008

Phil. Trans. R. Soc. B

223

219

View full text Add to dashboard Cite

show abstract

“…For instance, an analysis based on 50 genes using a sparse taxon sampling (21 species, with most of the animal phyla being represented by a single, often fast-evolving, species) and a simple model of sequence evolution (RtREVC ICG), resulted in a poorly resolved tree, in which even the monophyly of Bilateria was not supported (Rokas et al 2005). Since the approach used does not allow an efficient detection of multiple substitutions, we decided to do a comparable study in which we simultaneously improved the species sampling (from 21 to 57, including many slowly evolving species) and the model of sequence evolution (i.e.…”

Section: Introduction (A) the Limits Of Morphologymentioning

confidence: 99%

Improvement of molecular phylogenetic inference and the phylogeny of Bilateria

Lartillot

Piégay

2008

Phil. Trans. R. Soc. B

166

View full text Add to dashboard Cite

Inferring the relationships among Bilateria has been an active and controversial research area since Haeckel. The lack of a sufficient number of phylogenetically reliable characters was the main limitation of traditional phylogenies based on morphology. With the advent of molecular data, this problem has been replaced by another one, statistical inconsistency, which stems from an erroneous interpretation of convergences induced by multiple changes. The analysis of alignments rich in both genes and species, combined with a probabilistic method (maximum likelihood or Bayesian) using sophisticated models of sequence evolution, should alleviate these two major limitations. We applied this approach to a dataset of 94 genes and 79 species using CAT, a previously developed model accounting for site-specific amino acid replacement patterns. The resulting tree is in good agreement with current knowledge: the monophyly of most major groups (e.g. Chordata, Arthropoda, Lophotrochozoa, Ecdysozoa, Protostomia) was recovered with high support. Two results are surprising and are discussed in an evo-devo framework: the sister-group relationship of Platyhelminthes and Annelida to the exclusion of Mollusca, contradicting the Neotrochozoa hypothesis, and, with a lower statistical support, the paraphyly of Deuterostomia. These results, in particular the status of deuterostomes, need further confirmation, both through increased taxonomic sampling, and future improvements of probabilistic models.

show abstract

“…1a, Supplementary Fig. 1 and Supplementary Note 3.1) 8,13 . By virtue of their position on the tree of life, studies of choanoflagellates provide an unparallelled window into the nature of the unicellular and colonial progenitors of metazoans 14 .…”

mentioning

confidence: 99%

The genome of the choanoflagellate Monosiga brevicollis and the origin of metazoans

King

Westbrook²,

Young³

et al. 2008

Nature

Self Cite

1,032

1,024

View full text Add to dashboard Cite

Choanoflagellates are the closest known relatives of metazoans. To discover potential molecular mechanisms underlying the evolution of metazoan multicellularity, we sequenced and analysed the genome of the unicellular choanoflagellate Monosiga brevicollis. The genome contains approximately 9,200 intron-rich genes, including a number that encode cell adhesion and signalling protein domains that are otherwise restricted to metazoans. Here we show that the physical linkages among protein domains often differ between M. brevicollis and metazoans, suggesting that abundant domain shuffling followed the separation of the choanoflagellate and metazoan lineages. The completion of the M. brevicollis genome allows us to reconstruct with increasing resolution the genomic changes that accompanied the origin of metazoans.Choanoflagellates have long fascinated evolutionary biologists for their marked similarity to the 'feeding cells' (choanocytes) of sponges and the possibility that they might represent the closest living relatives of metazoans 1,2 . Over the past decade or so, evidence supporting this relationship has accumulated from phylogenetic analyses of nuclear and mitochondrial genes [3][4][5][6] , comparative genomics between the mitochondrial genomes of choanoflagellates, sponges and other metazoans 7,8 , and the finding that choanoflagellates express homologues of metazoan signalling and adhesion genes 9-12 . Furthermore, species-rich phylogenetic analyses demonstrate that choanoflagellates are not derived from metazoans, but instead represent a distinct lineage that evolved before the origin and diversification of metazoans (Fig. 1a, Supplementary Fig. 1 and Supplementary Note 3.1) 8,13 . By virtue of their position on the tree of life, studies of choanoflagellates provide an unparallelled window into the nature of the unicellular and colonial progenitors of metazoans 14 .Choanoflagellates are abundant and globally distributed microbial eukaryotes found in marine and freshwater environments 15,16 . Like sponge choanocytes, each cell bears an apical flagellum surrounded by a distinctive collar of actin-filled microvilli, with which choanoflagellates trap bacteria and detritus (Fig. 1b). Using this highly effective means of prey capture, choanoflagellates link bacteria to higher trophic levels and thus have critical roles in oceanic carbon cycling and in the microbial food web 17,18 .More than 125 choanoflagellate species have been identified, and all species have a unicellular life-history stage. Some can also form simple colonies of equipotent cells, although these differ substantially from the obligate associations of differentiated cells in metazoans 19 . Studies of basal metazoans indicate that the ancestral metazoan was multicellular and had differentiated cell types, an epithelium, a body plan and regulated development including gastrulation. In contrast, the last common ancestor of choanoflagellates and metazoans was unicellular or possibly capable of forming simple colonies, underscoring the abundant biologi...

show abstract

Animal Evolution and the Molecular Signature of Radiations Compressed in Time

Cited by 351 publications

References 41 publications

Deciphering deuterostome phylogeny: molecular, morphological and palaeontological perspectives

Deciphering deuterostome phylogeny: molecular, morphological and palaeontological perspectives

Improvement of molecular phylogenetic inference and the phylogeny of Bilateria

The genome of the choanoflagellate Monosiga brevicollis and the origin of metazoans

Contact Info

Product

Resources

About