Gene exchange in a ground cricket hybrid zone

Area of Science:

• Evolutionary Biology
• Population Genetics
• Entomology

Background:

• Ground crickets Allonemobius fasciatus and A. socius are sister species with a known mosaic hybrid zone in the eastern United States.
• Previous genetic studies of this hybrid zone relied heavily on protein electrophoresis to understand species interactions and gene flow.

Purpose of the Study:

• To discover and utilize novel genetic markers, specifically Random Amplification of Polymorphic DNA (RAPD), to differentiate between A. fasciatus and A. socius.
• To evaluate the congruence between newly identified RAPD markers and established protein electrophoresis markers in hybrid populations.
• To assess the extent of gene flow between these two closely related cricket species within their hybrid zone.

Main Methods:

• Identification and application of several Random Amplification of Polymorphic DNA (RAPD) markers capable of distinguishing between A. fasciatus and A. socius.
• Comparison of results obtained from RAPD markers with existing data from protein electrophoresis.
• Analysis of genetic structure and hybrid identification in mixed populations using both marker types.

Main Results:

• Discovery of multiple RAPD markers that effectively distinguish the two ground cricket species.
• Demonstration of congruence between RAPD markers and protein markers in identifying hybrids within mixed populations.
• Both RAPD and protein markers consistently indicate that gene flow between A. fasciatus and A. socius is significantly limited.

Conclusions:

• RAPD markers provide a valuable and effective tool for distinguishing between the sister cricket species A. fasciatus and A. socius.
• The congruence of RAPD and protein marker data strengthens the conclusion of restricted gene flow between these species.
• Limited gene flow suggests ongoing reproductive isolation despite the formation of a mosaic hybrid zone.