Invasive ecosystem engineer selects for different phenotypes of an associated native species

Area of Science:

• Ecology
• Evolutionary Biology
• Marine Biology

Background:

• Invasive ecosystem engineers significantly alter habitats, presenting novel challenges to native species.
• Native species in invaded habitats lack evolutionary history with the engineer, potentially facing new selective pressures.
• Caulerpa taxifolia, an invasive seaweed, is a habitat-forming ecosystem engineer.

Purpose of the Study:

• To investigate if the invasive seaweed Caulerpa taxifolia imposes novel selective pressures on the native bivalve Anadara trapezia.
• To determine if Caulerpa habitat selects for different phenotypes of Anadara trapezia compared to unvegetated habitats.
• To analyze the performance consequences of functional trait variation in Anadara under different habitat conditions.

Main Methods:

• Utilized a phenotypic selection framework to assess Anadara trapezia.
• Transplanted Anadara into both Caulerpa-invaded and unvegetated habitats.
• Measured performance linked to functional traits: shell morphology, gill mass, and palp mass.

Main Results:

• Phenotype-performance gradients in Anadara differed significantly between Caulerpa and unvegetated habitats.
• These selective gradients were more pronounced in the Caulerpa-invaded habitat.
• Alternate Anadara phenotypes exhibited high performance in Caulerpa habitat, differing from those dominant in unvegetated areas.

Conclusions:

• Caulerpa taxifolia acts as a significant agent of selection on native Anadara trapezia populations.
• Habitat modification by invasive species can drive evolutionary changes in native species.
• Understanding these interactions is crucial for predicting ecosystem responses to invasions.