Adaptive divergence in response to shared environmental pressures: examining gastropod shell exploitation by...

Area of Science:

• Marine Biology
• Ecology
• Evolutionary Morphology

Background:

• Gastropod shells exhibit morphological adaptations to intertidal zone pressures (wave exposure, predation).
• Hermit crabs utilize gastropod shells for protection, facing similar environmental challenges.
• Intraspecific variation in snail shell shape may be exploited by hermit crabs.

Purpose of the Study:

• To investigate if hermit crabs adaptively select intraspecific variation in snail shell shape.
• To compare shell shapes of snails and hermit crabs across different intertidal zones.
• To analyze the influence of environmental pressures on shell shape selection by hermit crabs.

Main Methods:

• Geometric morphometrics used to analyze shell shape and size.
• Comparison of snail shells and hermit crab-occupied shells for two species (Mancinella, Stramonita).
• Study conducted across upper and mid intertidal zones.

Main Results:

• Snail and hermit crab shell shapes varied by intertidal zone and species.
• Shell shape similarity observed between snails and crabs in specific zone-species combinations (Mancinella-mid, Stramonita-upper).
• Hermit crabs in the upper intertidal occupied the most extreme shell shapes for both snail species.

Conclusions:

• Hermit crab shell selection is influenced by both snail species and intertidal zone.
• Different ecological constraints lead to both similarities and contrasts in shell shape use.
• Hermit crabs demonstrate adaptive selection of snail shells, particularly in extreme environments.