The Pirarucu or Paiche (Arapaima spp) is considered the most emblematic fish of the Amazon and one of the largest freshwater fish in the world. Due to its size and meat quality, it is of great productive interest, with high and medium aptitude for different regions of Colombia, but due to intense fishing pressure, it has presented a drastic reduction of natural populations. The objective of this work was to evaluate the diversity and phylogenetic analysis of pirarucu from different places in Colombia, from the COI and ND2 genes. For this purpose, 50 dorsal fin samples were taken, of which 21 came from the Putumayo river basin (Tarapacá n=2, La Paya n=7, Leguizamo n=12), 10 from the Amazon basin, 12 from commercial farms in Valle del Cauca and 7 from Ecuador. DNA extraction was performed with a commercial kit and a fragment of the mitochondrial COI and ND2 genes was amplified for subsequent bidirectional sequencing. The sequences were edited using Geneious Prime 2023.2, BLAST was performed and then aligned using the MEGA 11 program. Diversity statistics were estimated using Arlequin, R and MEGA. The best nucleotide substitution model was determined and phylogenetic trees were constructed using a sequence of Heterotis niloticus as outgroup. In addition, the sequences were concatenated to construct phylogenetic trees of higher robustness. The COI clean sequences were 615 bpb, the ND2 sequences were 856 bpb. BLAST found high identity and similarity with the COI and ND2 sequences of Arapaima Gigas. The best nucleotide substitution model for the two genes was HKY. The average evolutionary divergence for COI was 0.01, while for ND2 it was 0.02. Five polymorphic sites with a heterozygosity of 0.40 were found for the COI gene, while for ND2 four sites were found, with 0.36 heterozygosity. Six different haplotypes were reported in COI and five in ND2 with the greatest divergence for the population of the Amazon river basin, followed by that of the Cauca Valley. Genetic distances show the highest values between the Amazon and Putumayo river basin populations. In general, the phylogenetic trees show a separation of the Putumayo River populations from those of the Amazon and a possible correspondence with animals from both sites for the samples from commercial cultivation. In conclusion, low genetic variation was found in the sequences, but it was possible to identify a different grouping of the Putumayo river basin populations with respect to those of the Amazon.
Keywords: Paiche; mitochondrial DNA; genetic resources; Amazonian fish