Phylogenetic convergence and multiple shell shape optima for gliding scallops (Bivalvia: Pectinidae).

Area of Science:

• Evolutionary Biology
• Phylogenetics
• Morphometrics

Background:

• Similar ecological pressures can lead distantly related species to evolve similar phenotypes.
• Bivalved scallops (Pectinidae) independently evolved gliding behavior at least four times.
• The evolution of gliding requires specific biomechanical adaptations for locomotion.

Purpose of the Study:

• To test the hypothesis of shell shape convergence in independently evolved gliding scallops.
• To investigate if gliding lineages exhibit similar phenotypic evolution.
• To explore the biomechanical underpinnings of gliding in different scallop lineages.

Main Methods:

• Utilized geometric morphometrics to analyze shell shape variation.
• Employed phylogenetic comparative methods to study trait evolution.
• Evaluated patterns of multivariate trait evolution and biomechanical parameters.

Main Results:

• Gliding scallops showed reduced morphological disparity and significant evolutionary convergence in shell shape.
• Gliding lineages converged on two distinct regions of morphospace.
• Biomechanical analyses revealed functional differences in how these scallop groups achieve gliding.

Conclusions:

• Convergent evolution has resulted in a common gliding morphotype in scallops.
• Despite a shared phenotype, distinct morphological subforms suggest two adaptive optima for gliding.
• This indicates that similar ecological demands can be met through functionally different evolutionary pathways.