Abstract
Aim: The present study was undertaken in Salem Black goat population for genetic analysis at molecular level to exploit the breed for planning sustainable improvement, conservation and utilization, which subsequently can improve the livelihood of its stakeholders. Materials and Methods: Genomic DNA was isolated from blood samples of 50 unrelated Salem Black goats with typical phenotypic features in several villages in the breeding tract and the genetic characterization and bottleneck analysis in Salem Black goat was done using 25 microsatellite markers as recommended by the Food and Agricultural Organization, Rome, Italy. The basic measures of genetic variation were computed using bioinformatic software. To evaluate the Salem Black goats for mutation drift equilibrium, three tests were performed under three different mutation models, viz., infinite allele model (IAM), stepwise mutation model (SMM) and two-phase model (TPM) and the observed gene diversity (He) and expected equilibrium gene diversity (Heq) were estimated under different models of microsatellite evolution. Results: The study revealed that the observed number of alleles ranged from 4 (ETH10, ILSTS008) to 17 (BM64444) with a total of 213 alleles and mean of 10.14±0.83 alleles across loci. The overall observed heterozygosity, expected heterozygosity, inbreeding estimate and polymorphism information content values were 0.631±0.041, 0.820±0.024, 0.233±0.044 and 0.786±0.023 respectively indicating high genetic diversity. The average observed gene diversities (He) pooled over different markers was 0.829±0.024 and the average expected gene diversities under IAM, TPM and SMM models were 0.769±0.026, 0.808±0.024 and 0.837±0.020 respectively. The number of loci found to exhibit gene diversity excess under IAM, TPM and SMM models were 18, 17 and 12 respectively. Conclusion: All the three statistical tests, viz., sign test, standardized differences test and Wilcoxon sign rank test, revealed significant deviation of Salem Black goats from mutation-drift equilibrium under IAM and TPM models, however, nonsignificant deviation under SMM model. The qualitative test of mode shift analysis supported the results under SMM indicating the absence of the genetic bottleneck in the recent past in Salem Black goats.
Highlights
India is bestowed with a diverse indigenous goat population with 23 recognized breeds, which have been evolved by farmers over centuries for various utilities
The qualitative test of mode shift analysis supported the results under stepwise mutation model (SMM) indicating the absence of the genetic bottleneck in the recent past in Salem Black goats
The variation between allelic diversity and heterozygosity was exploited as the basis for statistical tests to evaluate the mutation drift equilibrium of Salem Black goat population
Summary
India is bestowed with a diverse indigenous goat population with 23 recognized breeds, which have been evolved by farmers over centuries for various utilities. Most of these breeds are developed for meat and milk. All these breeds are well adapted to the agro-climatic conditions prevailing in their respective native tracts, tolerant to tropical heat, relatively more resistant to tropical diseases and thrive well with meager feedstuff mostly crop residues. Due to changing agricultural pattern some of these indigenous goats have declined over the past few decades. Microsatellites have been used successfully to define genetic relationships among different.
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