2007 Fiscal Year Final Research Report Summary
Investigation of speciation mechanisms in aphids
| Project/Area Number |
17370028
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biodiversity/Systematics
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| Research Institution | Hokkaido University |
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Principal Investigator |
AKIMOTO Shin-ichi Hokkaido University, Research Faculty of Agriculture, Professor (30175161)
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| Co-Investigator(Kenkyū-buntansha) |
AOKI Shigeyuki Rissho University, Faculty of Econany, Professor (30159280)
KATAGIRI Chihiro Hokkaido University, Institute of Low Temerature Science, Assistant Professor (90002245)
YAO Izumi Hokkaido University, Faculty of Science, Research Fellow (70374204)
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| Project Period (FY) |
2005 – 2007
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| Keywords | molecular phylogeny / mitochondria / speciation / geographic variation / host race / gall / parthenogenesis / aphid |
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| Research Abstract |
The present study attempted to clarify how the peculiar life cycle and reproductive modes of aphids have affected their speciation modes and genetic differentiation, focusing on aphid life cycles characterized by cyclic perthenogenesis. The results of the present study showed that the peculiar life cycles of aphids have led to frequent genetic differentiation and speciation. The scope of the present study was extensive, including the diverse subjects of gall formation and genetic differentiation, rapid speciation accompanied by the association of Aphis species wiith herbaceous plants, genetic differentiation between sexual and permanently asexual populations, speciation accompanied by a rapid change in the life cycle of a host-altemating aphid species, and genetic differentiation through the mutualistic relationships between an aphid species and the attending ants. The present study has clarified the interrelationship among the aphid life cycles, host adaptations, and genetic differentiation, thus having contributed to the understanding of biodiversity in herbivorous insects. For example, it has become clear that there is genetic differentiation among populations on respective host trees in the galling aphid Kaltenbachiella japonica. The present study indicated that the primary cause of the genetic differentiation is due to phenological differences in host individuals. The differences in host phenology prevent gene flow between host-associated populations, leading to genetic differentiation between populations. Another topic in the present study is the finding of polymorphism in mitochondrial haplotypes in the same breeding population of gall-forming aphids. In some species, haplotypes that differ by 3% to 7% in the COI sequence were found to coexist in the same breeding population. Such a large difference among haplotypes has not been reported for any insect or other animal species. Therefore, this issue is a promising subject to be addressed in the future study.
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