Unknown Paternity

Developing a self-sustaining ex situ population of giant pandas is strongly dependent on successful reproduction by a significant proportion of available individuals. This is attributable to the need to maintain as much of the original (founder) gene diversity as possible, avoiding inbreeding depression, which occurs with the loss of valuable 'wild' genes. The objective is not only to produce lots of giant panda offspring but rather young that represent all the valuable genotypes within the population (see Chapter 21). The genetic and demographic assessments from the 1996 masterplanning workshop revealed that there was excellent gene diversity in the captive population, with no need for more founders from nature (see Chapter 2).

However, the Biomedical Survey revealed that the genotypes of many captive-born young in the extant population were unknown. Only a few pandas were behaviourally capable of mating naturally due to widespread sexual incompatibility. At the onset of the Survey, virtually every breeding facility had only one or two natural breeders. The extraordinarily short and tricky window of opportunity (the two- to three-day oestrus period once annually) for each female exacerbated the challenge. The standard protocol was that managers allowed a female access to that facility's one available breeder each day she was in oestrus. Then, to maximise the chance of pregnancy, each mated female was immediately anaesthetized for AI with sperm from a non-breeding male. This scenario often occurred on sequential days of oestrus. It was not unusual to use one or more sires for breeding and two or more others as sperm donors: mating roulette. The impact of this practice became apparent when the Survey teams constructed first-cut pedigrees using studbook data (Xie & Gipps, 1999, 2001). Figure 3.3 represents a typical pedigree from one institution showing many individuals with unknown paternity. Without explicit sire identification, it is impossible to implement a valid genetic management programme -managers could be unknowingly mating related animals. As discussed by David et al. (in Chapter 10), this issue was tackled by developing a molecular genetics laboratory in China to sort out many panda

Figure 3.3. Pedigree from a representative institution showing the prevalence of giant pandas with unknown paternity (shaded). □, male; o, female; 4, cub that died without gender being determined.

paternities. Although 'missing links' remain (because of dead animals and the lack of DNA samples), these new data have allowed addressing the need for genetic management (see Chapter 10).

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