Extensive hybridisation and complex evolutionary history in the leafhopper genus Agnesiella (Hemiptera: Cicadellidae: Typhlocybinae)

Abstract

The subfamily Typhlocybinae (Cicadellidae) represents a globally distributed, species-rich lineage of leafhoppers. Despite significant advancements in morphological taxonomy and higher-level phylogenetics, species-level evolutionary dynamics within individual typhlocybine genera remain poorly understood. This study focuses on the endemic Oriental genus Agnesiella Dworakowska, which exhibits high species diversity in the Hengduan Mountains of Southwest China. Using whole-genome sequences of 48 individuals representing 40 Agnesiella species and 4 species from related genera, we reconstructed phylogenetic relationships, estimated divergence times and investigated patterns of hybridisation and introgression within this genus using single-copy orthologue sequences (SCOs), ultraconserved elements (UCEs) and single-nucleotide polymorphism sequences (SNPs). Our findings reveal a complex evolutionary history in Agnesiella, shaped by incomplete lineage sorting (ILS) and extensive interspecific gene flow, particularly within the subgenus Draberiella. The diversification of Agnesiella coincides with the orogenic and climatic changes in the Hengduan Mountains during the Miocene–Pliocene, which may have promoted allopatric isolation, secondary contact and hybridisation. Functional analysis of the introgressed genomic regions suggests their potential contribution to adaptive evolution, including enhanced metabolism of nitrogen compounds and plant secondary metabolites. These findings provide novel insights into the evolutionary dynamics of Typhlocybinae, emphasising the critical role of hybridisation and introgression in driving speciation and adaptation in insect lineages.