Host specificity of herbivorous insects promotes negative species–genetic diversity relationship

• Published in: Oikos Vol. 2025; no. 5
• Main Authors: Li, Qian‐Ya, Zhang, Linyi, Hu, Xinghua, Wang, Rong, Chen, Xiao‐Yong
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.05.2025
• Subjects: acorn weevils; Biodiversity; Curculionidae; Dominant species; Fagaceae; Fagaceae plants; Genetic diversity; Genetic variation; Genotypes; herbivore; Herbivores; Herbivory; Host plants; Host specificity; Insects; Lithocarpus; Plant communities; Species diversity; Trophic relationships; Tropical forests
• ISSN: 0030-1299; 1600-0706
• DOI: 10.1111/oik.10757

Although genetic diversity and species diversity in a community often covary, the direction and strength of the covariation vary. However, this variation in the relationship of these two diversities is poorly understood. Here we investigated the role of host‐specific herbivores in generating species–genetic diversity relationship in plant communities. We quantified host specificity for Fagaceae plants–acorn weevil bipartite networks in a subtropical forest and modeled the effect of weevil herbivory on the relationship. The results showed a consistently negative relationship between Fagaceae species diversity and the genetic diversity of the dominant species, Lithocarpus glaber. Our analysis showed this negative relationship arose from a positive effect of weevil host‐specificity on Fagaceae plant richness on the one hand and the negative effect of weevil host‐specificity on the genetic diversity of L. glaber on the other hand. This latter negative effect was possibly due to differentiated selection of weevils on different genotypes of L. glaber. Our study highlights the importance of considering trophic interactions and herbivore host‐specificity in explaining the species–genetic diversity relationship.