| Abstract |
Genetic diversity is essential in optimizing both conservation and utilisation strategies for animal genetic resources. Local poultry breeds make up most of the world’s poultry genetic diversity, and are still very impor¬tant in developing countries where they represent up to 95 percent of the total poultry population. Local Egyptian poultry breeds are highly adapted to harsh environmental conditions and thought to constitute genetic reservoirs. For instance, Fayoumi chicken breed can be seen as a unique breed from the viewpoint of disease resistance and Sinai chicken strain possesses superiority in heat tolerance. The development and increased focus on more efficient selection programmes have accelerated genetic improvement in a number of breeds. As a result, highly productive breeds have replaced local ones across the world. Moreover, intensive selection caused narrowing of genetic base and inbreeding which is associated with declines in both population fitness and disease resistance. This development has led to growing concerns about the erosion of genetic resources, as the genetic diversity of low productive local breeds is likely to contribute to current or future traits of interest and they are considered essential for maintaining future breeding options. The first problem for conservation is the lack of information, so the identification and genetic characterization of all breeds particularly local ones has high priority in the FAO global strategy. Information of poultry genetic resources is considered a useful model for studying conservation of genetic diversity in wild animal species. Therefore in this study, I evaluated the genetic diversity of Egyptian chickens and pigeons in order to apply this information for conservation purpose by using two different strategies. The first strategy (in chapter 2) was maximization of genetic diversity based on neutral microsatellites genetic markers while the second strategy (in chapter 3) was genetic improvement by low selective pressure based on functional gene polymorphisms.
For the first strategy, I evaluated the genetic structure, breeds diversity and the breed contribution to aggregate genetic diversity as important criteria for their conservation by utilising three different prioritization methods in order to set the priorities for conservation of Egyptian chickens and pigeons based on neutral genetic markers (microsatellites). For chickens, the six studied Egyptian populations showed a moderate level for both within-population (MNA = 4.9; HE = 0.595) and between-population (FST = 0.082) genetic diversity and were clustered into four clusters by STRUCTURE. Fayoumi, Dandarawy and El-Salam populations were assigned independently into their respective clusters while the remaining three populations (Baladi, Sinai and Golden Montazah) were clustered together forming admixed mosaic cluster. Regarding breed contribution to aggregate genetic diversity, Dandarawy breed contributed the most and ranked the first, while Fayoumi breed contributed negatively to aggregate genetic diversity and ranked the last. For pigeons, the six studied Egyptian populations showed moderate within-population (MNA = 4.10; HE = 0.584) and high between-population (FST = 0.211) genetic diversity. The Egyptian in addition to Japanese racing pigeon populations were clustered into six clusters. Krezly, Safi, Romani, Ablaq and Japanese racing populations were assigned independently into their respective clusters while the remaining two populations (Asfer Weraq and Zagel) appeared as a mosaic clusters. Zagel breed contributed the most and ranked the first, while Asfer Weraq ranked the last in the contribution for aggregated genetic diversity.
For the second strategy, I focused on the genes which might be related with effective utilisation of the poultry genetic resources. The polymorphisms of functional genes might be used as genetic markers for selection of high performance pigeons. For instance, the Lactate dehydrogenase gene family is involved in aerobic and anaerobic metabolism; therefore it determines muscle endurance, recovery and aerobic capacity. I found that the long allele (600bp) of Lactate dehydrogenase-A (LDH-A) gene showed significantly higher frequencies than short one (595bp) in the homing than non-homing in both Japanese and Egyptian pigeons and it might be useful for conservation and sustainable utilisation through improvement of local population’s performance. Also for wildlife, basic understanding of LDH-A genotype and homing ability might be useful for studying of wild migrating birds. Consideration of neutral genetic diversity and functional genes diversity in addition to breed merits and threat status, enabled us to balance the trade-offs between conserving genetic diversity as insurance against future uncertainties and current sustainable utilisation.
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