International Journal of Molecular Zoology, 2025, Vol.15, No.1, 20-28 http://animalscipublisher.com/index.php/ijmz 25 analysis that pathways such as calcium signaling pathways and glyceride metabolism pathways play a key role in feather formation, and these pathways are also species-specific. Yang et al. (2022) and Yang et al. (2024) conducted transcriptome comparisons between the white feather region and the gray feather region in the study of feather color patterns and found that genes related to melanin production, such as EDNRB2 and MLANA, were significantly downregulated in the white feather region, indicating that transcriptional regulation might be the key reason for the different colors. Xu et al. (2022) discovered gender-related gene expression differences in feather sacs. For instance, TYRP1 expression was higher in female geese, while ASIPexpression was higher in male geese, which was also consistent with the differences in their feather colors. 6.3 Integration with epigenomic data Researchers combined functional genomics in the chromosomal genomic sequencing of Hungarian white geese and discovered a regulatory network of miRNA and mRNA, which is related to the development of feather cysts, indicating that epigenetic regulation may play an important role in feather coloring (Zhou et al., 2024). If epigenetic data such as miRNA expression profiles can be combined with the existing genomic and transcriptome information, a more comprehensive understanding of the genetic mechanism and regulatory mode of feather color in domestic geese can be achieved. 7 Environmental and Hormonal Influences 7.1 Effects of light, diet, and stress In the genomic analysis of Huoyan geese, it was found that they can adapt to the cold northern climate. This is because they have some genes related to stress response, metabolism and immunity in their bodies. Wen et al. (2023) believe that these genes may be related to feather color, indicating that environmental stress can drive genetic changes related to feather color. Although there are not many studies on how light and nutrition affect the color of goose feathers at present, in other birds, there is already a lot of evidence suggesting that these factors can regulate pigment deposition and feather quality. Wen et al. (2023) also discovered many stress-related genes in goose breeds adapted to different climates, supporting the view that environmental stress can affect feather color by regulating gene pathways. 7.2 Endocrine regulation of plumage color Hormones related to gender have a significant impact on the feather color of geese. Xu et al. (2022) found in their study on Holdobaggy geese that the color of the feathers on the backs of female gogings is darker than that of males, which is closely related to the higher melanin content in the feather sacs and the expression differences of melanin-related genes such as TYRP1 and ASIP. Sex hormones may start to play a role during embryonic development, regulating the expression of certain key genes to cause differences in feather color between male and female geese. This regulatory mechanism may be the result of the interaction between gender-specific hormone signals and the genetic mechanism of melanin synthesis. 7.3 Gene-environment interactions Through selective clearance analysis, researchers found that pigment-related genes such as TYRP1 and KIT, as well as genes related to environmental adaptation such as PIP5K1B and NMNAT3, were all subject to natural selection in goose flocks under different climates (Ren et al., 2021; Wen et al., 2021; 2023), indicating that the interaction between genes and the environment plays an important role in feather color formation. Researchers also identified candidate genes in the same group of geese that are related to both feather color and climate adaptation, indicating that environmental stress may directly affect the coloring genes or function through a mechanism where one gene controls multiple traits (pleiotropy). This changing relationship indicates that when studying the color of goose feathers, both genetic and environmental factors need to be taken into account in order to understand the mechanism of feather color formation more comprehensively. 8 Case Study: Genetic Basis of White vs. Gray Plumage in Wanxi White Goose 8.1 Background and phenotypic description The Wanxi White Goose is a domestic goose breed in China. It has two main feather colors: white feathers and
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