BGI, Chinese Academy of Sciences and other offices jointly published a Cell article: "Recognizing relatives" based on some genes and phenotypes is not reliable

For a long time, it has been a common practice in many researches to construct species relationship trees from species morphological characteristics and molecular data

On April 20, "Cell" published a study by a Chinese-foreign joint team led by Chinese scientists

The study shows that in the process of rapid species differentiation, some random events may also lead to distant species with similar phenotypes

Human genome not always most similar to chimpanzee

"As early as about 160 years ago, Darwin proposed that all living things on earth today evolved from a common ancestor, and the process of continuous bifurcation and evolution from the common ancestor to form the current species group constitutes the 'tree of life'

DNA is the genetic blueprint of most organisms.

"But in fact, using DNA data and morphological characteristics to construct species relationship trees, respectively, often yields contradictory results, and there is still a lack of research explaining why such contradictions occur

"We often observe this kind of conflict between the molecular tree and the morphological tree in groups that have experienced rapid species differentiation

Take humans, chimpanzees, and gorillas for example.

This incomplete lineage splitting phenomenon has occurred in many taxa that have experienced a species explosion

Building species relationship trees based on partial genes and phenotypes is unreliable

To understand the impact of incomplete lineage splitting on the evolution of species morphology and traits, the researchers in the paper used marsupials

"The little mountain monkey is the only extant species of the South American marsupial

It is precisely because of this phenotypic similarity that the earlier evolutionary relationship based on morphological features suggested that the mountain monkey is more closely related to the Diprotodon kangaroo and koala, and it was speculated that the American mountain monkey originated in Australia

However, the new study, using whole-genome data from the mountain monkey and other marsupials, proves that the mountain monkey should be the sister group to all of Australia's marsupials

Further analysis revealed that the molecular tree constructed in more than 50% of the marsupial genome is inconsistent with the real species differentiation process, and the similarity between the gorilla monkey and some Australian marsupials is greater than that between the Australian marsupials.

In order to test the above conjecture, the researchers used museum specimens to determine that the curved shape of the humerus, the height of the spinous process of the spine, and the shape of the incisors of the little mountain monkey are more similar to those of the diprotodon kangaroos and koalas

The evolution of species phenotype is considered to be the result of long-term adaptation of species to the environment, that is, mutations generate new genes and new phenotypes, and new genes are spread through reproduction

The researchers said that this study shows that it is unreliable to build a species relationship tree by relying only on partial genes and partial phenotypes.
Whole genome data is the gold standard for reconstructing the evolutionary history of species
.
And, incomplete lineage splitting can serve as a mechanism to explain the conflict between genomic species relationship trees and phenotypic variation
.

Related paper information:

https://doi.
org/10.
1016/j.
cell.
2022.
03.
034

Reporter Zhang Wenjing