The Genomic and Evolutionary Analysis
Seasonal breeding in the Anseriformes (雁科) presents an outstanding opportunity to study the evolution of seasonal breeding in animals. Seasonal breeders are divided into "long day" breeders and "short day" breeders based on when they become reproductively active. Ducks are long day breeders in natural environment: their gonads enlarge and begin to produce gametes when the day gets longer (Spring); but they are dormant in Fall and Winter (Fig. 6). On the other hand, for short day breeders, such as geese, their gonads behave in a reversed fashion --- active in Fall and Winter, but dormant in Spring and Summer. Seasonal reproduction occurs in natural environment, but artificial selection has established Leghorn chicken (來亨雞) and Tsaiya duck (菜鴨) as two major strains for year-round egg production. However, for other domestic fowls, such as Taiwan Country chicken (台灣土雞), Muscovy duck (番鴨), and White Roman goose (白羅曼鵝), their seasonality remains and their reproduction is limited to their specific seasons. The Muscovy duck is a long day breeder, whereas the White Roman goose is a short day breeder.
Muscovy duck and White Roman goose meats are commonly consumed in Taiwan. Despite the agricultural and biological importance of Muscovy ducks and White Roman goose, breeding and genetics studies have been hindered by the lack of reference genome sequences. We have just completed the whole genome sequencing of Mandarin duck, Muscovy duck, and White Roman goose, and I will conduct transcriptomic analyses of hypothalamus, pituitary and gonad gene expression profiles in Muscovy duck and White Roman goose and characterize the reversed seasonality by comparative hormonal and transcriptomic analyses between male Roman geese and male Muscovy ducks. Identifying the genes that control the seasonality of these birds will by my first priority. These genome sequences will also be useful for mapping reads obtained by resequencing more breeds of duck and geese, which will facilitate the identification of SNP markers for genomic marker–assisted breeding. It will also be useful for improving the utility of the domesticated birds as a biomedical model. In addition, the genes we will identify are related to seasonal breeding and may be used as markers for breeding longer laying duration to increase egg production.