Problems in Estimating Divergence Times

2015 Fiscal Year Final Research Report

• Project/Area Number: 25440219
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Biodiversity/Systematics
• Research Institution: The Institute of Statistical Mathematics
• Principal Investigator: Hasegawa Masami 統計数理研究所, 統計思考院, 名誉教授 (60011657)
• Co-Investigator(Kenkyū-buntansha): ADACHI JUN 統計数理研究所, データ科学研究系, 准教授 (30370092)
• Co-Investigator(Renkei-kenkyūsha): YONEZAWA TAKAHIRO 復旦大学, 生命科学学院, 副教授 (90508566)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 分岐年代推定 / 分子系統学 / 古顎類 / エピオルニス / 古代DNA解析

Outline of Final Research Achievements

Palaeognathae including ostiches, emus, rheas and tinamous is believed to have originated in Gondwana-derived continents. We recovered nuclear genome fragments as well as mitochondrial genomes from extinct elephant birds of Madagascar, and reconstructed a robust phylogenomic time-tree for Palaeognathae. In contrast to the prevailing theories, our tree based on morphological characters free from convergence placed the fossil paleognths from the Northern Hemisphere as the basal lineage. Such molecular and morphological evidence strongly suggests the Northern Hemisphere origin of Palaeognathae. They were probably flying birds, as estimated by the mitochondrial substitution rate, and migrated to the Southern Hemisphere and explosively speciated around the Cretaceous-Paleogene boundary. They then extended their distribution to the Gondwana-derived landmasses by the overseas dispersal, and gigantism subsequently occurred independently on each landmass.

Free Research Field

分子系統学