![]() ![]() The branches in downy feathers only include the ramus and barbules, whereas most adult chicken feathers are bilaterally symmetric and include a rachis, ramus, and barbules. ( B) Developing and mature embryonic and adult chicken feathers. ( A) Downy feather, contour feather, and flight feather. Different types of feather in a chicken. It is also a rare opportunity to explore both macro- and microevolutionary questions in the same model. ![]() Feather, thus, provides an excellent model to study how genetic and developmental changes can evolve rapidly. A great diversity of feather can also be observed within a bird species, especially in domesticated birds ( Bartels 2003 Chen et al. Feather diversification allows different species of birds to be widely distributed on earth and adapt to various ecological niches in water, land, and air ( Chatterjee 2015). As feather is complex in structure, it has the potential to allow various phenotypic changes to evolve ( fig. 1). 2014).įeather diversification apparently began in theropod dinosaurs in which a wide range of feathers could already be observed ( Xu et al. Compared with reptilian and avian scale, however, feather is well organized in cylindrical and tubular structures of the follicle ( Prum 2005 Xu et al. Feather is believed to have evolved from scale, and novel scale-feather converters have just been identified ( Wu et al. One lineage of feathered theropod dinosaurs survived the mass extinction and became the ancestor of birds ( Chatterjee 2015). Finally, we discussed future research directions.įeather first appeared in dinosaurs in the Jurassic period, around 165–150 Ma ( Xu et al. Specifically, this review includes the following topics: 1) Diversity of feather morphotype 2) feather diversity among different breeds of domesticated birds, including variations in pigmentation pattern, in feather length or regional identity, in feather orientation, in feather distribution, and in feather structure and 3) diversity of feathers among avian species, including plumage color and morph differences between species and the regulatory differences in downy feather development between altricial and precocial birds. We summarize recent studies of feather evolution in terms of genetics, genomics, and developmental biology and provide perspectives for future research. In this review, we discuss three levels of feather diversity: Feather morphotypes, intraspecific variations, and interspecific variations. Many questions remain to be answered by multidisciplinary approaches. Although the development of feather has been studied for decades, genetic and genomic studies of feather diversity have begun only recently. Feather diversity is striking in many aspects. ![]()
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