Amazing stuff!
The first author, i.e. Zeyuan Chen, of this study works at the Senckenberg Research Institute and Natural History Museum Frankfurt, in my hometown Frankfurt am Main, Germany.
"... To create an accurate evolutionary ‘tree’ for the phylum, researchers sequenced whole genomes from 13 species, allowing them to look at genetic markers from 77 species in total, including members of every major subgroup of mollusks.
The findings revealed that monoplacophorans were one of the first offshoots of the Conchifera, a group within mollusks that includes almost all the highly recognizable types, including octopuses and their relatives as well as clams and snails.
The analyses also revealed just how genomically diverse mollusks are, with lots of rearrangements and repetitive sequences—features that may have allowed the group’s physical diversity to emerge. ..."
"... In their new study, scientists analysed the genomes of 77 mollusc species, representing all eight major living groups, including lesser-known forms like deep-sea monoplacophorans and worm-like solenogasters. Using cutting-edge genomic techniques, the team reconstructed a detailed evolutionary tree and confirmed key hypotheses about mollusc ancestry. ..."
From the editor's summary and abstract:
"Editor’s summary
Genome sequencing has allowed for a much greater understanding of how species relate to one another than did earlier morphology-based approaches. A particularly difficult phylum to study using genomic data has been mollusks, which encompass species ranging from squid to sea snails, in part due to their high levels of heterozygosity and repetitiveness. Chen et al. sequenced 13 new complete genomes from across the phylum to assemble a new phylogeny for Mollusca. They resolved several highly debated nodes and provide additional genomes for future study of this highly diverse and genomically complex phylum. ...
Abstract
Extreme morphological disparity within Mollusca has long confounded efforts to reconstruct a stable backbone phylogeny for the phylum. Familiar molluscan groups—gastropods, bivalves, and cephalopods—each represent a diverse radiation with myriad morphological, ecological, and behavioral adaptations.
The phylum further encompasses many more unfamiliar experiments in animal body-plan evolution.
In this work, we reconstructed the phylogeny for living Mollusca on the basis of metazoan BUSCO (Benchmarking Universal Single-Copy Orthologs) genes extracted from 77 (13 new) genomes, including multiple members of all eight classes with two high-quality genome assemblies for monoplacophorans. Our analyses confirm a phylogeny proposed from morphology and show widespread genomic variation. The flexibility of the molluscan genome likely explains both historic challenges with their genomes and their evolutionary success."
Cracking the Mollusc Code: Genomes Reveal the Ancient Ancestor of Your Garden Snail (original news release) "An international team of scientists has cracked a longstanding evolutionary mystery surrounding molluscs, one of the most diverse groups of animals on Earth. The groundbreaking research, published today in Science, resolves the family tree for molluscs, bringing long-awaited clarity on their evolutionary history and resolving debates that have persisted for decades."
Nudibranchs like this Flabellina affinis are among the varied forms of mollusks.
Fig. 1. Mollusca timetree.
No comments:
Post a Comment