Speciation studies in the genomic era.

Since Darwin's era, speciation has been one of the most central issues in evolutionary biology studies. Understanding the processes of species origin is crucial in deepening our understanding of the formation of species biodiversity, which is essential for their protections. However, speciation research has been challenging due to the rather complex evolutionary histories of many extant species. In recent years, with the continuous advancements in genomic sequencing techniques, significant advances have been achieved in the field of speciation researches. In this review, we overview speciation study advances, especially in the concepts and latest developments in research methods for studying speciation in the genomic era, encompassing the major research aspects: species delimitation, bifurcating speciation, hybrid speciation, polyploid speciation, reproductive isolation genes and speciation genes. Furthermore, we discuss the limitations of these studies and methods. Finally, we provide the outlook on the future challenges and directions in speciation researches.