MITOCHONDRIAL HETEROPLASMY IN CRUSTACEANS AND ITS IMPLICATIONS TO SPECIES DELIMITATION: A MINI-REVIEW

Mitochondrial DNA sequences are commonly used as molecular markers for species identification and phylogenetic studies due to their uniparental inheritance among other features. This uniparental transmission typically results in organisms having a single type of mitochondrial DNA (homoplasmy). However, there are instances where organisms with different mitochondrial haplotypes (heteroplasmy) are found, and this phenomenon complicates the function of the mitochondrial DNA region as a tool for species identification and evolutionary inference. Given the economic importance of the crustacean species, this review investigates the prevalence of heteroplasmy in crustaceans and its potential impact. To date, heteroplasmy has been reported in 12 crustacean species, with most cases (66.7%) occurring at the dual tRNA alanine/valine position. Heteroplasmy can be detected using digestive enzymes and various polymerase chain reaction-based methods. The presence of mitochondrial heteroplasmy in crustaceans affects the species delimitation process. This review highlights the presence of heteroplasmy in crustaceans and the importance of identifying populations with heteroplasmic organisms, especially economically important crustaceans in fisheries and aquaculture. Future efforts in developing diagnostic markers, conducting long-term, large-scale monitoring, and using next-generation sequencing technology for mitochondrial genome sequencing will aid in characterising heteroplasmy in crustaceans.