Phenotypic plasticity and morphological integration in a marine modular invertebrate

Area of Science:

• Marine biology
• Evolutionary biology
• Ecology

Background:

• Colonial invertebrates like corals display complex modularity, complicating morphological evolution studies.
• Caribbean gorgonian corals show decoupled evolution at polyp and colony levels, meaning polyp changes don't necessitate colony form changes.
• Pseudopterogorgia bipinnata, a Caribbean gorgonian, exhibits significant morphological variation across diverse reef habitats.

Purpose of the Study:

• To investigate intraspecific patterns of morphological integration in Pseudopterogorgia bipinnata.
• To characterize the genotype/environment relationship and phenotypic plasticity within this species.
• To understand how modular features (polyps) and colonial features (branches) are integrated.

Main Methods:

• Compared genetic variation using microsatellite loci, mitochondrial (MSH1) and nuclear (ITS) DNA sequences, and ITS2 DGGE banding patterns across populations in Belize, Panama, Colombia, and the Bahamas.
• Conducted phylogenetic analysis of ITS1-5.8S-ITS2 sequences.
• Analyzed phenotypic integration of modular and colonial traits in a Belizean population using third-order partial correlation coefficients.

Main Results:

• No concordant genetic variation was found in ITS2 genotypes despite distinct morphotypes.
• Phylogenetic analysis suggested P. kallos might be a shallow morphotype of P. bipinnata.
• Significant integration was observed between polyp and colonial traits, with some traits showing independence while others depended on modular features.

Conclusions:

• Module integration in gorgonian corals is dynamic and can be shifted, switched, or canalized.
• Modular marine organisms like corals exhibit adaptable strategies through module coupling or decoupling, facilitating adaptation to various marine benthic environments.