The Evolution of Galectins in Bivalves

Bivalves are currently under threat of disease; these species aren't able to adapt and respond to diseases in the same way that vertebrates do because they don't have an adaptive immune system. Bivalves are economically important to the aquaculture industry worth billions of USD. Ecologically these species are incredibly important for building ecosystems and being a reliable food source. Bivalves can be found across the globe and populate both saltwater and freshwater environments. This study aimed to investigate the evolution of galectins, proteins involved in pathogen recognition, aiming to deduce possible factors affecting their evolution and possible trends in their divergence. This was the largest study done on galectin evolution for bivalves, and relied heavily on the quality of published genomes. Unfortunately, genome quality did affect the galectins that were ultimately included in the phylogenetic trees. Cut offs had to be applied to prevent the fragmentation of bivalve genes from creating inaccurate trees. The evolution of galectins tended to follow two trends. Firstly, that the smaller galectins (<2 CRD) diverged away from the large galectins (>2 CRD). Secondly, the CRD themselves all evolved independently of each other. Hopefully, further studies can be done on looking at the chemical composition and possibly selective breeding programs. There are some interesting trends pointed out that can?t be explained by the evolution of these species. How does the evolution of the CRD effect their linking? Does it change what pathogen they link to? Would selective breeding to develop resistance to diseases be feasible or do these proteins take too long to adapt? This study laid the ground work for many further investigations into bivalve galectins.