Fitness and Morphology Support Genetic Differentiation Across Different Geographic Scales in a Native Insect...

Area of Science:

• Ecology
• Evolutionary Biology
• Genetics

Background:

• Native species can rapidly evolve when utilizing invasive species as new food sources.
• The Australian soapberry bug (Leptocoris tagalicus) provides a model for studying rapid adaptation.
• Investigating differentiation across different host plants and geographic locations is key to understanding evolutionary responses.

Purpose of the Study:

• To investigate the genetic and trait differentiation of Leptocoris tagalicus populations.
• To assess adaptation in response to feeding on invasive versus native host plants.
• To determine the heritability of traits and hybrid performance in L. tagalicus.

Main Methods:

• Genetic analysis (FST) to quantify population differentiation.
• Field observations and multi-generation experiments to track trait adaptation.
• Hybridization experiments to assess trait heritability and hybrid vigor.

Main Results:

• Moderate genetic differentiation was found between Northern Territory (NT) and New South Wales (NSW)/Queensland (Qld) populations (FST = 0.033).
• Low genetic differentiation was observed between NSW and Qld populations (FST = 0.008), regardless of host plant.
• Ongoing adaptation in proboscis length was evident in insects on invasive hosts, with high heritability for proboscis length (H2 = 0.48) and body size (H2 = 0.4).

Conclusions:

• Leptocoris tagalicus biotypes show ongoing genetic differentiation across different spatial scales.
• Rapid adaptation, particularly in proboscis length, is occurring in response to novel invasive host plants.
• High heritability and superior performance of F1 hybrids suggest strong selective pressures and potential for further evolutionary divergence.