| Driven by economic interests,wild snakes are often illegally poached and laundered in legal market by mixing them up.Due to the lack of effective methods at present to segregate wild from farmed snakes,the continouse crime activities disturbed snake farming and impaired conservation of wild resources.By using the King rat snake,Elaphe carinata,a species being extensively farmed and poached,this study established two indices based on liver mass and body measurements,named the liver-head index(Ilh)and liver-body index(Ilb),to segregate snake origins.For the tow indices,Fisher ’s discriminant was used to test the effectiveness of origin assignment.Results showed both Ilh and Ilb revealed correctness of 96.9%for the wild group,74.1%for the farm group,and 86.4%for overall.However,both the two indices showed significant inter-sex difference in both wild and farmed snakes.The values of the two indices of farmed males were close to those of wild females,leading to a risk of 36.4%for farmed males being assigned to wild females mistakingly.When sex is known,the correct rate of 1lh to assigne males back to their origin reached 100%for wild snakes,90.4%for farmed snakes,and 94.1%for overall.The correctness of this index to assign females was as high as 100%for wild snakes,81.3%for farmed snakes,and 92.9%for overall.The asignement power of Ilb was similar to that of Ilh reaching an overall correctness of 90.5%for females and 94.1%for males.The two indices are easy to measure,and suitable for dead or incomplete carcass.They are potentially applicable to other snake species farmed with similar technology.Meanwhile,ND2 gene of mitochondrial genome and single-copy gene c-mos of nuclear genome were used as markers to test the copy number of the two genomes of skeletal muscle using fluorescent real-time quantitative PCR approch.20 ng of the dorsal spinal muscle was collected from each of 32 wild king rat snakes and 27 farmed king rat snakes and the copy number of mitochondrial genome(NND2)and nuclear genome(Nc-mos)and total genome(Nt)based on which indices were eatablished namely the ratio of NAD2 to Nc-mos(Rm-u,percent of NND2 to Nt(Pmt),percent of Nc-mos to Nt(Pnu),and ratio of linear genomic density(RLD).Inter-sex and inter-group differences were tested and the power of origin assignment were assessed.The results showed that there were no gender differences for all indices.Rm-u had significant inter-group difference(P=0.023),and the difference of RLD was even greater(P=0.007).Pmt and RLd were the most effective indices for origin assignment though their assignment power was still limited and conditional.The correctness of origin assignment of Pmt was 80.8%for farm group,45.2%for wild group,and 61.4%for overall;The correctness of RLD was 73.1%for farm group,54.8%for wild group,and 63.2%for overall.In conclusion,the two liver mass based indices Ilh and Ilb were very effective to assign origin of the snake when sex in known(in practice sexing could be easily done using reproductive organ),while DNA copy number of skeleton muscle could not be applicable to origin assignment due to limited discrimination power. |
