Source: School of Life Sciences
Written by: School of Life Sciences
Edited by: Wang Dongmei

Speciation mechanism is a core topic in the field of evolutionary biology. It is the primary driver of biodiversity. Allopatric speciation requiring an unbroken period of geographical isolation has been the standard model of neo-Darwinism for the last 70 years. While doubts have been repeatedly raised, strict allopatry without any gene flow remains a plausible mechanism in most cases.

The research group of Prof. Suhua Shi and Prof. Chung-I Wu at School of Life Sciences, Sun Yat-sen University took a variety of mangrove plants growing in the coastal zone on both sides of the Strait of Malacca (between Indian Ocean and western Pacific Ocean) as research objects and systematically studied their population structure and geographical pattern by using genome sequences, geographic data and computer simulations. They found that intermittent gene flow caused by periodic changes of sea level was the key to speciation and proposed and verified a new theoretical model of speciation “Mixing-Isolation-Mixing Cycles Model” or MIM model.

This work entitled “Speciation with gene flow via cycles of isolation and migration: insights from multiple mangrove taxa” was published in the latest issue of National Science Review. It provides a new viewpoint to explain the formation mechanism of global biodiversity hotspots and is an important theoretical innovation in the field of speciation research in China in recent years. The School of Life Sciences of Sun Yat-sen University is the first and corresponding author unit. Associate Professor Ziwen He is the first author, and Prof. Suhua Shi and Prof. Chung-I Wu are the co-corresponding authors. This research was funded by the National Natural Science Foundation of China and the National Key Research and Development Plan.

This article has solved the long-standing problem of correctly understanding the role of gene flow in the process of speciation, provided an example of global periodic climate changes promoting the formation of biodiversity hotspots, and received several positive reviews from top scholars in the field. Trevor Price, a professor at the University of Chicago and a leading evolutionary biologist, said the study combined cutting-edge genomic analysis with important data sets to come up with powerful conclusions that shed light on the mechanisms of marine biodiversity. Richard J. Abbott, a renowned evolutionary biologist and a professor at the University of St Andrews in the United Kingdom, said the MIM model successfully explained the speciation of mangroves in the Indo-West Pacific region, and this convincing result set the scene for future studies on speciation with historical geographical information and the origin of hybrid zones. Loren H. Rieseberg, winner of the Darwin-Wallace Medal, Fellow of the Royal Society and a professor at the University of British Columbia, wrote a review article entitled “A new model of speciation”, praising the MIM model as a novel and important contribution to the field of speciation.

Link to the paper: https://academic.oup.com/nsr/article/6/2/275/5057885