Phoretic Poecilochirus mites specialize on their burying beetle hosts

Area of Science:

• Ecology
• Evolutionary Biology
• Animal Behavior

Background:

• Species interactions drive coevolutionary adaptations, leading to symbiont specialization.
• Specialization enhances symbiont fitness within established associations but can decrease adaptability to novel partners.
• The fitness consequences of host-symbiont discrimination in natural populations are not fully understood.

Purpose of the Study:

• To investigate the fitness consequences of host-symbiont specificity in a complex of two cryptic mite species and their burying beetle hosts.
• To determine if mite species exhibit differential fitness when associated with preferred versus non-preferred burying beetle species.
• To assess the reciprocal fitness effects of these mite-beetle interactions on host populations.

Main Methods:

• Experimental association of two cryptic *Poecilochirus* mite species with their typical and non-typical sympatric burying beetle hosts (*Nicrophorus* spp.).
• Quantification of mite reproductive success and fitness metrics across different host associations.
• Evaluation of the impact of mite presence on burying beetle fitness and offspring care.

Main Results:

• Mite fitness significantly decreased when reproducing alongside a non-preferred burying beetle host, confirming specialization.
• Evidence suggests that burying beetle species are better adapted to their typically associated mite species.
• The overall fitness effect of *Poecilochirus* mites on burying beetles was negative in laboratory experiments.

Conclusions:

• The studied *Poecilochirus* mites exhibit host specialization, with fitness penalties incurred when interacting with non-native burying beetle species.
• These specialized mite-beetle interactions represent a form of competition or parasitism, negatively affecting host fitness.
• Findings highlight the intricate coevolutionary dynamics and fitness trade-offs in specialized symbiotic relationships.