Spatial variation in susceptibility to infection in a snail-trematode interaction

Area of Science:

• Ecology
• Evolutionary Biology
• Parasitology

Background:

• Parasite local adaptation predicts higher infectivity to sympatric hosts.
• Previous work on Microphallus sp. and Potamopyrgus antipodarum in Lake Alexandrina showed habitat-specific infectivity.
• This study re-investigated parasite-host interactions in shallow and deep water snail populations.

Purpose of the Study:

• To re-evaluate parasite local adaptation in Microphallus sp. infecting Potamopyrgus antipodarum.
• To assess parasite development rates in sympatric and allopatric snail hosts.
• To investigate potential clinal variation in snail susceptibility and parasite infectivity.

Main Methods:

• Field collection of snail parasites (Microphallus sp.) and hosts (Potamopyrgus antipodarum) from shallow and deep water habitats.
• Experimental infection trials to measure parasite infectivity across different host populations.
• Monitoring of parasite development within hosts to assess fitness consequences.

Main Results:

• Parasites originating from shallow water demonstrated higher infectivity and faster development in shallow-water snails.
• Parasites from deep water did not exhibit increased infectivity or development in deep-water snails.
• Evidence suggests clinal variation in snail susceptibility, with shallow-water snails being more susceptible.

Conclusions:

• Shallow-water snails exhibit greater susceptibility to Microphallus sp. infection compared to deep-water snails.
• Asymmetric local adaptation may be driven by gene flow from shallow to deep water or by habitat-specific host condition differences.
• Findings highlight the complexity of parasite-host coevolutionary dynamics in spatially structured populations.