Every species exhibits distinctive craniofacial morphologies; thus, these features have been traditionally used as one of the basic species classificatory criteria. Human beings, for example, distinguish individuals by their facial appearance, implying that there are also some individual differences in craniofacial morphology within the species Homo sapiens. Craniofacial morphology is a complex but interesting trait that reveals morphological variety within a species while maintaining the particular morphology of the species. Although common features are main topics of study in developmental biology, the diversity or polymorphisms are essential factors for consideration with regard to evolution. It is also simply interesting to contemplate how differences between individuals within a species are generated during developmental or life processes. Recently, genetic backgrounds responsible for such variations have been analyzed using quantitative trait loci (QTL) analysis methods in which phenotypes are treated as quantitative traits. In this chapter, we focus on the craniofacial morphology of the medaka and introduce our approach for the genetic dissection of the underlying mechanisms that generate morphological diversity in the medaka head region.
KeywordsQuantitative Trait Locus Inbred Line Inbred Strain Congenic Strain Geometric Morphometrics
The author thanks collaborators Drs. Tetsuaki Kimura, Hidetoshi Inoko, Gen Tamiya, Kiyoshi Naruse, and Hiroyuki Takeda, and Drs. Hiroshi Mitani and Syoji Oda, for their excellent assistance recording data from medaka closed colonies. The work presented here was supported in part by the Research and Study Program of Tokai University Educational System General Research Organization and by a Grant-in-Aid for Scientific Research on Priority Areas “Systems Genomics” from the Ministry of Education, Culture, Sports, Science and Technology in Japan.
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