Morphogenetic diversity of the selected hatchery populations of an Indian major carp (Labeo rohita, Hamilton, 1822) in the Mymensingh region of Bangladesh

Environmental changes due to the domestication of wild population in hatchery conditions often lead to morphogenetic alterations in fish. Therefore, this study aimed to determine the genetic purity, demographic history, and population structure of Labeo rohita collected from three hatcheries in Bangladesh using a geometric morphometric approach in conjunction with mtDNA cyt b gene sequences and microsatellite markers. The geometric morphometric analysis revealed significant variation in centroid size (body size) among the different populations of L. rohita. However, MANCOVA and subsequent ANCOVA models showed no significant variation in body shape (relative wraps, RW_s) among those populations. Both DNA-based techniques amplified all genotypes and revealed a high degree of genetic diversity across all populations. Clustering analyses based on the Neighbour-Joining (NJ) phylogenetic approach found that the hatchery populations have indisputably diverged from the wild populations. The study of haplotype networks, neutrality testing, and mismatch distributions revealed a complex population expansion pattern involving genetic introgression resulting from human translocation. This tendency is exacerbated further by anthropogenic factors, resulting in the loss of various alleles from hatchery populations. The unevenness of pair-wise F_ST and the hierarchical analysis of molecular variance of population structure showed a distinct variation between wild and hatchery populations. This genetic loss occurs due to improper domestication processes of the hatchery populations. Ignorance of appropriate hatchery procedures may lead to adverse selection by using poor seed leading to stock deterioration in the hatchery population. This study could help to establish appropriate breeding strategies and provide essential information for the genetic improvement program of L. rohita.