Managing the genetic diversity of animal populations using cryobanks: optimizing the constitution of ex situ collection?
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The genetic diversity of populations is important for their long-term conservation and adaptive potential. Nevertheless, there is an erosion of genetic variability in all populations, whether a small population under conservation or a large breed under selection. Many countries have conserved animal genetic resources ex situ , with the creation of cryopreserved collections. These cryopreserved genetic resources could open up new prospects for managing the genetic diversity of animal populations. Currently, there are as many strategies for conserving cryopreserved genetic resources as there are cryobanks. The aim of our study is to examine some parameters for optimizing the constitution of a gene bank.
Results
We performed simulations of animal populations ( i.e . selection or conservation) using different types of breeding strategy and changing (i) the size and age of the cryopreserved collection or (ii) the management of cryopreserved collections (entry and exit of frozen semen).
We found that the age of genetic resources was the predominant factor for populations under selection, as this factor also quantifies the lag in breeding values. A more massive stocking of recent individuals seems to be the most relevant strategy for mobilizing ex situ genetic resources in a breeding scheme. For populations in conservation, older reproductive material becomes highly relevant. A cryobank with a large number of old individuals enables better management of matings and avoids too rapid an increase in inbreeding over the long term, while the use of a more moderate number of old individuals enables some genetic progress to be maintained, but offers fewer possibilities for managing genetic diversity. Continuous collection supply is a relevant option for population management. Whatever the breeding strategy, the use of OCS can help mobilize ex situ genetic resources in animal breeding programs.
Conclusions
Cryopreserved genetic resources are an invaluable help in the management of domestic populations. It is important to continue research in order to optimize the use of cryopreserved genetic resources, and to set up collection management recommendations that are relevant and adapted to breeding programs.
