Through various DNA analyses, the presence of a single species of Harpagifer was discovered, contrasting current records. However, there are three highly genetically differentiated groups of the family of these spiny animals present in Patagonia.
In the sub Antarctic zone, the fish suborder Nototenoidae is of little interest to the industry or fisheries. However, its ability to withstand temperatures close to 0°C and the environmental variables to which it has been exposed in recent years due to climate change have made the scientific community put its efforts into deciphering its real adaptation to future scenarios.
For this, it is important to reliably estimate their classification, considering the importance of these fish in the marine ecosystems of the southern hemisphere. Currently, the taxonomic record indicated that there are two species of the Harpagiferidae family in the sub Antarctic zone: Harpagifer bispinis, present throughout Patagonia, and H. palliolatus, a fish endemic to the Falklands Islands.
In order to rectify this information, a group of scientists undertook the task of analyzing the natural populations of the two species mentioned through genetic analysis, ranging from Patagonia (west) to the Falkland Islands, passing through the Strait of Magellan. The researchers used two approaches in parallel: traditional DNA markers (based on mitochondrial genes and widely used for decades) and genomic DNA analysis, also called SNP (Single Nucleotide Polymorphism), which correspond to multiple markers dispersed in the genome.
“The environmental characteristics, and the little mobility of the adult Harpagifers made us suppose that we should be able to find genetic differentiation between Patagonia and Falklands, but the question was whether we should consider them as two different species;” this was the approach put forward by Dr. Nicolás Segovia, researcher at the Millennium Institute for Biodiversity of Antarctic and Sub-Antarctic Ecosystems (BASE), at the Millennium Institute for Coastal Socio-Ecology (SECOS) and lead author of the study.
Using traditional markers, the researchers found no genetic differentiation between Patagonia and Falklands, which suggests that, in the area studied, Harpagifer is composed of a single species, in contrast to current records. However, the genomic analyzes did determine a high genetic variation in the area, even managing to detect two groups of populations, one north and one south of the Strait of Magellan, in addition to a third highly differentiated group present in the Falklands Islands.
“This study opens several questions about this group of fish and studies of the distribution of genetic diversity in the area. Could the Strait of Magellan be a barrier for species with little mobility? How many of what we historically consider to be different species really are?” said Dr. Segovia.
“Analyzing the biogeographic patterns and the evolutionary history of the organisms of the Southern Ocean requires the use of integrative analyzes that include different disciplines (morphological analysis, traditional markers, genomic markers, among others). The objective of the work was to show that the results based on genomic data (SNPs) are not enough to describe and/or discriminate species,” added Dr. Claudio González-Webar, from the Center for Dynamic Research of High Latitude Marine Ecosystems (IDEAL) of the Austral University of Chile (UACH), who participated in the study.
The researcher added: “If we only had kept the genomic data, we probably would have described three species of Harpagifer, but that was not the case.”
The study, published in the scientific journal Proceedings of the Royal Society B, finally exposes the need to put into perspective the suitability of each study tool to determine the genetic variability existing in one territory.