Integrated morphometric and molecular approaches to screen hybrid from wild Labeo rohita and Catla catla parent populations

Abstract Background: Interspecific hybrids of rohu ( Labeo rohita ) and catla ( Catla catla ) are common, especially in India due to constrained breeding. These hybrids must segregate from their wild parents as part of conservational strategies. In this study, we screen the hybrid from wild Labeo rohita and Catla catla parents using both morphometric and molecular approaches. Methods & Results: The carp samples were collected from Jharkhand and West Bengal, India. The correlation and regression analysis of morphometric features are considered superficial but could be protracted statistically by clustering analysis and further consolidated by nucleotide variations of one mitochondrial and one nuclear gene to differentiate hybrids from their parents. Out of twenty morphometric features, six were used for clustering analysis. The clustering analysis showed discrete separation among rohu, catla, and their hybrids when the data points were plotted in a low-dimensional 2-D plane using the first 2 principal components. Out of forty selected SNP positions of the COX1 gene, hybrid showed 100% similarity with catla. Concerning SNP similarity of the 18S rRNA nuclear gene, the hybrid showed 100 % similarity with rohu but not with catla thus exhibiting its most probable paternal origin as rohu that confirms their parental source of sperm (rohu) and ovum (catla). Conclusions: Along with clustering analysis the SNP comparison study together points towards strong evidence of interspecific hybridization between rohu and catla, as these hybrids share both morphological and molecular differences with either parent. However, this screening process will be further consolidated by analysing more sequences.