Feathers are the most complex integumentary structures and their evolution has been one of most attended topics in evolutionary biology and paleontology. Until recently feathers have been considered to be unique to birds, though their presence was inferred in several theropod dinosaurs based on both their close phylogenetic relationships with birds and some osteological correlates, e.g., quill knobs and pygostyles. Since the discovery of the feathered compsognathid theropod Sinosauropteryx in 1996, numerous fossils of many theropod groups and even three ornithischian groups preserving feathers have been recovered from the Jurassic and Cretaceous deposits of northeastern China, Russia, Germany, and Canada. These fossils demonstrate that feathers of various morphotypes have a wide distribution among dinosaurs, and in particular, the presence of monofilamentous integumentary structures in some relatively basal dinosaurs and several pterosaurs led to the hypothesis that the first feathers might have appeared approximately 2.3 million years ago. The phylogenetic distribution of various dinosaur feathers shows an evolutionary trend of increasing complexity closer to birds, concurring with the predictions from a developmental model of living birds, but some of these morphotypes are absent in living birds. Importantly, recent developmental and genomic studies have discovered some feather-specific genes, revealed some molecular mechanisms regulating feather development and regeneration, and provided new comparative data on integumentary structures, which can be combined with fossil data to understand feather evolution. A better understanding of feather evolution requires multifaceted and integrative approaches, yet fossils necessarily provide the final test of any evolutionary model.

Feathers have diverse forms with hierarchical branching patterns and are an excellent model for studying the development and evolution of morphological traits. The complex structure of feathers allows for various types of morphological changes to occur. The genetic basis of the structural differences between different parts of a feather and between different types of feather is a fundamental question in the study of feather diversity, yet there is only limited relevant genetic or molecular data on feather development. In the past few years we have conducted (1) studies of the transcriptomes from various parts of feathers, (2) in situ hybridization studies of specific keratin genes, (3) ectopic expression of mutant keratin genes, and (4) studies of the effect of knock-down expression of beta keratin genes on feather development. These studies provided abundant data for understanding the genetic basis of feather diversity. In my talk, I shall present a summary of our studies.

フェノロジーとは、季節に応じて見られる生物現象の研究であり、植物では開花・結実・展葉などが対象とされる。例えば、季節的な繁殖同調は個体間の交配に必須であり、実際、どのようなメカニズムで繁殖の同調がなされているかについての野外研究が欠かせない。私達は、アブラナ科の多年草ハクサンハタザオを対象に分子フェノロジーの研究を進めている。季節応答を遺伝子発現などの分子遺伝学的手法を用いて研究するのが分子フェノロジーである。例えば、植物種の多くは、気温の季節変化に応答して一定の時期に花を咲かせる。ところが、気温の季節変化はあくまで長期的な傾向であり、その実態は大きいノイズを含んだ情報である。高解像度分子フェノロジー（HMP: high-resolution molecular phenology）データを得ることにより、花成抑制遺伝子FLC（FLOWERING LOCUS C）が過去6週間の低温を記憶するかのように調節されることが示された。さらに、全遺伝子を対象としたトランスクリプトーム、ヒストン修飾解析の結果を紹介する。最後に、分子フェノロジー研究の展望について議論したい。