Homoploid hybridization signals due to ancestral subdivision: a case study on the D lineage in wheat

Abstract

19Homoploid hybrid speciation has been reported in a wide range of species since the 20 exploitation of genome sequences in evolutionary studies. However, the interference 21 of ancestral subdivision has not been adequately considered in many such 22investigations. Using the D lineage in wheat as an example, we showed clearly that 23 ancestral subdivision has led to false detection of homoploid hybridization signals. 24We develop a novel statistical framework by examining the changes in shared 25 ancestral variations and infer on the likelihood of speciation due to genuine 26 homoploid hybridization or ancestral subdivisions. Applying this to wheat data, we 27 found that homoploid hybridization was not involved in the origin of the D lineage 28 contrary to the now widely held belief. This example indicates that the significance of 29 homoploid hybrid speciation is likely exaggerated. The underlying methodology 30 developed in this study should be valuable for clarifying whether homoploid 31 hybridization has contributed to the speciation of many other species. 32 33