Evolutionary relationship between 2 phyla may lead to other discoveries – study

New sequencing technology revealed that Kamptozoa and Bryozoa form their own.

The secret to healing what ails you lies within your own DNA (photo credit: DREAMSTIME)
The secret to healing what ails you lies within your own DNA
(photo credit: DREAMSTIME)

Two phyla of aquatic animals may have split off much earlier than scientists previously thought and formed their own group, according to a study published in ScienceAdvances.

The technology that led to this discovery could light the way for scientists to understand more deeply the living world's earliest evolutionary trends and how closely related different species are.

What happens when the fields of evolution and genomics interact? Meet phylogenomics, the analytical method that combines genome data and evolutionary reconstructions to compare and contrast entire genomes for the larger understanding of the evolution of a species.

A team of researchers from St. Petersburg State University in Russia, along with Japan’s University of Tsukuba and Okinawa Institute of Science and Technology focused specifically on two phyla of aquatic animals: Kamptozoa and Bryozoa. 

The two phyla are closely related to other animals including snails, earthworms, leeches and ribbon worms, the peer-reviewed study explained. Researchers discovered that they broke away from mollusks and worms at an earlier time than previously thought, thus forming a distinct group.

A DNA double helix is seen in an undated artist's illustration released by the National Human Genome Research Institute to Reuters on May 15, 2012. (credit: REUTERS/NATIONAL HUMAN GENOME RESEARCH INSTITUTE/HANDOUT)A DNA double helix is seen in an undated artist's illustration released by the National Human Genome Research Institute to Reuters on May 15, 2012. (credit: REUTERS/NATIONAL HUMAN GENOME RESEARCH INSTITUTE/HANDOUT)

New technology led to the breakthrough

With advanced technology, the researchers sequenced a transcriptome of four species of Kamptozoa and two species of Bryozoa that was 96% complete. For reference, previous transcriptomes only succeeded in providing 20-60% completeness.

A transcriptome is a reflection of a genome expressed in RNA, which DNA transcribes to provide instructions that a gene needs to create proteins, a press release spelled out. Analyzing transcriptomes can assist biologists with understanding the evolution of a species.  

"In our view, data completeness and quality are crucial to address difficult phylogenetic questions since these eliminate at least some sources of errors, leading to fluctuations in resulting trees," the study stated. 

"In our view, data completeness and quality are crucial to address difficult phylogenetic questions since these eliminate at least some sources of errors, leading to fluctuations in resulting trees."

The study

Using data with such a high degree of completeness allowed the researchers to predict proteins of the animals and compare them with other creatures, both closely and distantly related. This led to the confirmation that Kamptozoa and Bryozoa form their own group, called Polyzoa.

The research confirmed what biologists had hypothesized over a century ago. Our main finding is that the two phyla belong together,” Dr. Konstantin Khalturin, a staff scientist at the Okinawa Institute of Science and Technology Graduate University, said in a press release. “This result was originally proposed in the 19th century by biologists who were grouping animals based on what they looked like.”

 

More evolutionary discoveries could be on the way

In what could have significant implications for future evolutionary research, the sequencing technology used in the study can generate excellent transcriptomes for any species. Therefore, “there is no more reason to use low-quality datasets with large proportion of missing genes for phylogenomics,” according to the study.

“We’ve shown that by using high quality transcriptomic data we can answer a long-standing question to the best of our current techniques,” Khalturin explained. The advanced dataset generated in the study with these techniques could be used in the future to reveal how other animals are evolutionally related to each other.