Rearrange the family tree of animals

A study led by Brown University biologist Casey Dunn uses new genetic engineering to answer pre-questioned questions about animal evolution. This is a research project on the most comprehensive reproductive system to date, including data on 40 million new pairs of DNA taken from 29 different animal species.

The study, published in Nature, solves some long-standing arguments about the relationship between animal groups and at the same time creates some surprises. A great shock is: the jellyfish comb - the normal and extremely weak jellyfish with very developed tissues - is separated from other animals without tissue, and even has the front of the foam Ordinary sea. This finding raises a question about the root of the animal genealogy, in which the sponges are placed at the base.

'The finding indicates that either jellyfish evolved independently from other animals, or sponges that simplify themselves through evolution. Along with other types of evidence, this finding could dramatically change our way of thinking about multicellular animals, 'said Dunn, a professor of ecology and evolutionary biology at Brown. 'These amazing surprises, along with interesting insights into the relationship between living animals, make the project fascinating'.

Strategic jellyfish (Photo: iStockphoto / Klass Lingbeek- van Kranen)

Charles Darwin introduced the idea of ​​' genealogy ' in his powerful book entitled ' Origin of Species '. The sketch of the system tree is the only illustration in that book. 150 years from the date it was released, many relationships between animal groups are still unclear. While there have been many great advances in understanding genes, it is possible to produce a whole genome map of a species for comparison, there are millions of species in the world. This is simply not the time to arrange these genetic maps.

To be able to understand the genealogical tree - without studying the entire genome map of the species - Dunn and colleagues collected data, called activation sequences, from the genes of the 29 animals that they We have little knowledge in the distant branches of the genealogy tree, including jellyfish, centipedes and other molluscs. Scientists analyzed this data along with the genetic data of 48 other species, such as humans and fruit flies, to find the most chemically modified genes.

The aim of the method is to study a large number of genes from many animals - an improvement over genetic comparison methods with limited numbers of genes or species. This new process is not only more comprehensive, it is also more intensive. Dunn's project requires 120 processors in computer clusters located in laboratories around the world

Dunn and his colleagues have:

- Clearly affirm some of animal relationships, including the existence of a skinless invertebrate group, such as arthropods or nematodes.

- Solve convincingly the contradictory evidence around other relationships, such as the close relationship of polyps to spiders rather than insects.

- Find out new relationships, such as the close bond between nemertea worm, hand-rolled animal, or mollusca two tomorrow.

'What's interesting is that these new information changes our basic understanding of the natural world - information found in basic biological books and natural historical paintings', Dunn. said, 'although the family tree of living animals still needs a lot of time to complete, it is clearer. And these results show that the new gene method will help us at least solve some problems that were previously impossible. '

The team includes Andreas Hejnol, David Matus, Kevin Pang, William Browne, Elaine Seaver and Mark Martindale of the University of Hawaii; Stephen Smith of Yale University; Greg Rouse of the University of California - San Diego; Mathhias Obst of Kristineberg Marine Research Station, Sweden; Gregory Edgcombe of the Natural History Museum, London; Martin Sorensen and Reinhardt Kristensen of Copenhagen University; Steven Haddock of Monterey Bay Ocean Research School; Akiko Okusu of Simmons College; Ward Wheeler from the American Museum of Natural History; and Gonzalo Giribet from Harvard University.

The National Science Foundation has funded the project of Perfecting the Genealogy of Live Animals.