Evolution and development of facial bone morphology in threespine sticklebacks.

Area of Science:

• Evolutionary developmental biology
• Comparative osteology
• Fish skeletal morphology

Background:

• Skeletal morphology evolves through changes in developmental mechanisms.
• The opercle (OP) bone in ray-finned fish exhibits significant evolutionary variation.
• Threespine sticklebacks are a key model organism for studying vertebrate evolution.

Purpose of the Study:

• To investigate the developmental basis of opercle (OP) shape and size evolution.
• To understand how environmental shifts influence skeletal development and morphology.
• To identify genetic factors contributing to OP morphological changes.

Main Methods:

• Comparative analysis of opercle (OP) morphology in anadromous and freshwater threespine sticklebacks.
• Developmental timing assessment of OP bone deposition.
• Quantitative trait locus (QTL) mapping to identify genetic underpinnings.

Main Results:

• Alaskan anadromous threespine sticklebacks transitioning to a lake environment evolve smaller and reshaped opercle (OP) bones.
• This morphological change involves reduced bone deposition along a specific body axis.
• The developmental timing of OP formation is altered early in development.
• A significant quantitative trait locus (QTL) on linkage group 19 influences this opercle (OP) phenotype.

Conclusions:

• Environmental adaptation, such as lake residency, can rapidly drive evolutionary changes in skeletal morphology.
• Developmental plasticity and genetic factors interact to shape evolving bone structures.
• The opercle (OP) serves as a valuable model for studying the evolution of developmental mechanisms in vertebrates.