" NM, natural mating; h AI, artificial insemination; c Inferred, twins are different sex; d Inferred, only one possible parent; e ND, not determined; ^ A single case of mixed paternity was observed for twins SB 495 and SB 496 who were sired by SB 329 and SB 308, respectively.

distribution (Fig. 10.6). For each centre, we subdivided the pair-wise comparisons to groups that were presumed 'unrelated' (presuming the founders were unrelated) and to groups with kinship estimates of 0.5 (first-order relatives), 0.25 (grandchildren and grandparents) and 0.125 (first cousins). In both centres, there were two peaks of pair-wise comparisons for each group. In comparing varying kinship (based on pedigree structure determined from Figs. 10.4 and 10.5), mean related-ness values were bimodal with a 'left' major peak with a normal distribution of low relatedness, and a second 'more related' peak, likely a reflection of closer kin relationships among some smaller group of individuals not known to be close relatives (see Fig. 10.6). The second, 'right-most' related peak reflects historic kinship not apparent in the pedigree structure. This empirical measure allows zoo managers to identify heretofore unidentified close relatives that occur in pedigrees derived from tiny free-ranging populations.

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