Discovery calls into question accuracy of traditional methods for developing evolutionary trees of animals
Can a type of shrew be more related to an elephant than to other shrews? According to researchers at Milner Center for Evolution at the University of Bath (UB) in the United Kingdom, it’s possible, and their genetic study into convergent evolution may lead to improved use of genetic sequencing for the development of precision medicine treatments and clinical laboratory testing.
In fact, the UB study suggests traditional anatomical methods for determining the evolutionary relationships between species may not be as accurate as once thought, an article in SciTechDaily reported.
Nevertheless, the UB’s research into convergent evolution is unlocking new insights into how genes evolve over time and this new knowledge may help researchers develop genetic tests that more accurately identify different diseases and health conditions.
Additionally, studies that bring a better understanding of how beneficial genetic mutations work their way into a species’ genome might also aid researchers in developing personalized clinical laboratory testing and therapies based on manipulating a patient’s genetic sequences in ways that would be beneficial.
The UB researchers published their findings in the journal Nature Communications Biology, titled, “Molecular Phylogenies Map to Biogeography Better than Morphological Ones.”
Gene Sequencing More Accurate at Determining Evolutionary Relationships
The UB study suggests that existing evolutionary (phylogenetic) trees may need to be reconsidered. To put a finer point on the findings, a UB news release on the study states, “determining evolutionary trees of organisms by comparing anatomy rather than gene sequences is misleading.”
The UB scientists used genetic sequencing to quickly—and more cost effectively—determine evolutionary relationships as compared to traditional morphology (anatomy and structure), according to the news release.
They found genetic data that revealed surprising relationships about where the sequenced species originated, and which differed with prior conclusions that were drawn based on the species’ appearance. The findings suggest there may be need to “overturn centuries of scientific work in classifying relation of species by physical traits,” the UB scientists said.
Molecular Data Leads to New Insights into Convergent Evolution
The UB study’s use of genetic sequencing led the researchers to a greater understanding of convergent evolution, defined by “a characteristic evolving separately in two genetically unrelated groups of organisms,” according to UB.
For example, wings are a widely developed characteristic. But they are not necessarily a sign of relatedness when it comes to birds, bats, and insects.
“Now with molecular data, we can see that convergent evolution happens all the time—things we thought were closely related often turn out to be far apart on the tree of life,” Wills said, adding, “Individuals within a family don’t always look similar; it’s the same with evolutionary trees, too.”
Family Trees: Morphology Versus Molecular
In their paper, the UB researchers acknowledged the importance of phylogenies (evolutionary history of species) in areas of biology, including medicine. They aimed to study a better way to produce accurate phylogenetic trees.
“Phylogenetic relationships are inferred principally from two classes of data: morphological and molecular,” they wrote, adding, “The superiority of molecular trees has rarely been assessed empirically.”
So, they set out to compare the two approaches to building evolutionary trees:
- Traditional morphology analysis, and
- Phylogenetic trees developed using molecular data.
Using 48 pairs of morphological and molecular trees, they mapped data geographically.
“We show that, on average, molecular trees provide a better fit to biogeographic data than their morphological counterparts, and that biogeographic congruence increases over research time,” the researchers wrote.
Biogeography a Better Gauge of Relatedness than Anatomy
The study also found animals on molecular trees lived geographically closer as compared to groups on morphological trees.
For example, molecular studies put aardvarks, elephants, golden moles, swimming manatees, and elephant shews in an Afrotheria group, named for Africa, which is where they came from. Therefore, the biogeography matches, however the appearances of these mammals clearly do not, the UB scientists point out.
“What’s most exciting is that we find strong statistical proof of molecular trees fitting better not just in groups like Afrotheria, but across the tree of life in birds, reptiles, insects, and plants,” said Jack Oyston PhD, UB Department of Biology and Biochemistry Research Associate and first author of the study, in the news release.
The researchers believe their findings support the accuracy of genetic-themed trees.
“It being such a widespread pattern makes it much more potentially useful as a general test of different evolutionary trees. But it also shows just how pervasive convergent evolution has been when it comes to misleading us,” Oyston added.
Advantages of Molecular Data
In their Nature Communications Biology paper, the UB scientists wrote that molecular data offer up these advantages over morphology:
- Widely available in vast quantity.
- Opportunity exists to “search, repurpose, and reanalyze sequenced data alongside novel sequences.”
- Less subjectivity in researchers’ analysis.
- Well-developed data at the ready and “still in their infancy.”
The University of Bath’s study of convergent evolution, phylogenetic trees, and comparison of molecular data versus morphology, has implications for medical laboratories. Should their research lead to new insights into how genes evolve over time, diagnostics professionals may have new information to identity diseases and work with others to precisely treat patients.
—Donna Marie Pocius