A strong colonizer rules the trematode guild in an intertidal snail host

Area of Science:

• Ecology
• Parasitology
• Community Ecology

Background:

• Trematode communities in snail hosts often exhibit skewed species abundance distributions.
• Understanding the ecological factors driving these distributions is crucial for community ecology.

Purpose of the Study:

• To investigate the roles of supply-side, niche, and competition theories in explaining a highly skewed trematode community.
• To identify the life-history traits and strategies of the dominant trematode species, Microphallus simillimus.

Main Methods:

• Collecting and dissecting the snail host Heleobia australis across four seasons and three habitats in Bahía Blanca estuary, Argentina.
• Analyzing trematode community structure and species interactions within snail hosts.

Main Results:

• One trematode species, Microphallus simillimus, comprised 87% of individuals, with 15 other species having <3% abundance.
• Microphallus simillimus was a weak competitor but exhibited strong colonization ability, likely leading to host preemption.
• Trematode species aggregated in summer, with dominant species excluding subordinates, and no significant niche partitioning was observed.

Conclusions:

• Extremely skewed species abundance distributions can result from highly skewed colonization abilities, rather than solely from niche differentiation or competitive exclusion.
• Preemption and strong recruitment are key factors allowing Microphallus simillimus to dominate the trematode guild despite weak competitive ability.