Deep phylogeographical structure and parallel host range evolution in the leaf beetle Agelasa nigriceps

Area of Science:

• Ecology
• Evolutionary Biology
• Entomology

Background:

• Insect herbivore diversification is driven by insect-plant interactions and dietary breadth changes.
• Understanding host range evolution is key to insect diversification mechanisms.

Purpose of the Study:

• Investigate the phylogeographical pattern of Agelasa nigriceps to infer host range evolutionary history.
• Determine if the recent adoption of Pterostyrax hispidus as a host plant is a recent evolutionary event.

Main Methods:

• Phylogenetic analyses using mitochondrial DNA sequences.
• Amplified fragment length polymorphism (AFLP) analysis.
• Examined geographical variation in host use.

Main Results:

• High phylogeographical structure in Agelasa nigriceps across Japan, suggesting glacial refugia.
• No genetic structure detected correlating with host plants.
• Populations utilizing Pterostyrax hispidus were polyphyletic, indicating independent origins.

Conclusions:

• Host range expansion to the novel host Pterostyrax hispidus is a recent, ongoing, and polyphyletic phenomenon.
• Host range evolution in herbivorous insects can occur repeatedly in response to similar environmental changes.
• Environmental changes, like increased abundance of Pterostyrax hispidus, can drive rapid host range evolution.