12 May 2026: New study on immune gene diversity reveals conservation risks for harbour porpoises
A study by Celemín and colleagues, titled “Evolution and Organisation of MHC II Genes in Harbour Porpoises: Insights From Long-Read Cetacean Genome Assemblies, Whole Genome Re- Sequencing and Locus- Specific Genotyping”, was published in the journal Molecular Ecology in June 2025.
The Major Histocompatibility Complex (MHC) is a region in a vertebrate animal’s (animals with a backbone) genome (the species’ full DNA code) that allows their immune system to detect pathogens (microbes which cause diseases). The more diverse a species’ MHC genes are, the better its immune system will respond to diseases. Studying MHC genetic diversity provides crucial information to assess the health of a species and is a key factor in preparing management plans for the recovery of endangered wildlife.
The harbour porpoise has an endangered subspecies (the Black Sea subspecies) and a critically endangered population (the Baltic Sea population). This study assessed MHC diversity in harbour porpoises from six different regions, including samples from the threatened subspecies and population. It also analysed the MHC genes of 19 species of cetaceans (whales, dolphins and porpoises) and land mammals (pig, cow, and hippopotamus, all of which share ancestry with cetaceans), to understand the evolution and structure of MHC genes in harbour porpoises.
The authors found reduced MHC diversity in the endangered Black Sea subspecies, which makes them vulnerable to disease outbreaks. Thus, they recommend that extensive conservation and management measures be implemented for them. Similar concerns were expressed for the critically endangered Baltic Sea population, which also demonstrated low MHC diversity. However, too few samples from this population were used in the study to obtain reliable results. Therefore, further MHC studies are needed for this population, using larger sample sizes. Animals that are not fully healthy are less able to withstand stress from other pressures. Studies like this one are important, as they can highlight populations that require more immediate management action in the face of multiple anthropogenic stressors.
Read the full paper by Celemín et al here: https://doi.org/10.1111/mec.70006
Photo credit: Peter Duley