The Andean farmer conserves and maintains the existing genetic diversity of potato cultivars by means of clonal propagation of tubers . However, surveys of traditional farms showed that botanical seed propagation was used for disease elimination, stock rejuvenation and the creation of new cultivars . Electrophoretic surveys based on 542 tubers collected from 18 markets sampled in the Cusco area disclosed a total of 229 different cultivars from diploid, triploid and tetraploid forms of Solanum tuberosum L . These could be classified by isozyme cluster analysis into four major groups and six minor groups . However, they did not agree with groups based on flesh or skin color . It is therefore concluded that all genotypes belong to a single, large gene pool with considerable gene flow between cultivars of different groups . When the samples were grouped by the three most common tuber skin colors, namely red/pink ('Q'ompis type'), purple ('Yana Imilla' type), and yellowish/brown ('Yuraq Kusi' type), similar allozymes were observed in all three classes . The structure of the isozymic phenotypes within each group indicate that they may have been derived as segregants after outcrossing of diverse parental types . In order to provide further evidence for the origin of new types by hybridization, two segregating diploid progenies were generated by crossing purple by yellow skin types . In the resulting F1, most of the tuber phenotypes observed in the Andean varieties were reproduced in these crosses . It can be concluded that the Andean potatoes form a large and plastic gene pool amplified and renovated by outcrossing followed in some cases by human selection of desirable phenotypes .

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An intercomparison study was conducted to determine the presence of processed animal proteins (PAPs), including meat and bone meal (MBM) from various species, in animal feed. The performances of different methods, such as microscopy, polymerase chain reaction (PCR), immunoassays, and a protocol based on iquid chromatography (LC), were compared. Laboratories were asked to analyze for PAPs from all terrestrial animals and fish (total PAPs); mammalian PAPs; ruminant PAPs; and porcine PAPs. They were free to use their method of choice. In addition, laboratories using microscopy were asked to determine the presence of PAPs from terrestrial animals, which is applicable only to microscopy. For total PAPs microscopy, LC and some immunoassays showed sufficient results at a concentration as low as 0.1% MBM in the feed. In contrast, PCR was not fit for purpose. In differentiating between MBM from terrestrial animals and fishmeal, microscopy detected 0.5% of terrestrial MBM in feed in the presence of 5% fishmeal, but was less successful when the concentration of MBM from terrestrial animals was 0.1%. The animal-specific determination of MBM from mammals or, more specifically from either ruminants or pigs, by PCR showed poor results, as indicated by a high number of false-positive and false-negative results. The only PCR method that scored quite well was applied by a member of the organizer team of the study. Immunoassays scored much better than PCR, showing sufficient sensitivity but some deficiency in terms of specificity. The results also demonstrated that the reliable determination of MBM from ruminants has not been resolved, especially for low concentrations of MBM (0.1%) in feed. Comparison of the results for mammalian MBM from all methods indicated that, for control purposes, the immunoassay method, especially when applied as dipsticks, could be used as a rapid screening method combined with microscopy to confirm the positive samples. However, implementation of such a system would require that the immunoassays were previously validated to demonstrate that this approach is fit for purpose. The determination of ruminant or porcine PAPs by immunoassays was more difficult, partly because the MBM in this study contained about 50% bovine and porcine material, thereby reducing the target concentration level to 0.05%.

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