2002 Fiscal Year Final Research Report Summary
STUDY ON DISRUPTIVE SELECTION CAUSEING SPECIATION IN COMPLEX PREDATOR-PREY SYSTEMS
| Project/Area Number |
13440227
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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 |
生態
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
SAITO Yutaka Hokkaido Univ., Graduate School of Agriculture, Professor, 大学院・農学研究科, 教授 (20142698)
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| Co-Investigator(Kenkyū-buntansha) |
HASEGAWA Eisuke Hokkaido Univ., Graduate School of Agriculture, Assistant Professor, 大学院・農学研究科, 助手 (40301874)
KUDO Syunichi Naruto Educational Univ., Associate Professor, 学校教育学部, 助教授 (90284330)
YAMAUCHI Atushi Kyoto Univ., Center of Ecological Research, Associate Professor, 生態学研究センター, 助教授 (40270904)
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| Project Period (FY) |
2001 – 2002
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| Keywords | TETRANYCHIDAE / SOCIALITY / PHYLOGENY / DEFENSE / SPECIATION / SCHIZOTETRANYCHUS CELARIUS / DESRUPTIVE SELECTION / ANTI-PREDATOR |
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| Research Abstract |
We studied on the factors which caused complex predator-prey systems in the nature from several behavioral view points. First we analyzed the phylogenies of the target species focused on and revealed that the species concerned are monophyletic. Next the behavioral traits of several prey and predator species under experimental conditions. For example, the function of the large and continuous nests of Schizotetranychus longus Saito was beneficial to cooperative defense through the concentration of many adults over a long period, although the nests are relatively vulnerable to predatory intrusion because of their large sizes. On the other hand, the smaller, scattered nests (with at most ten eggs) constructed repeatedly by a single Schizotetranychus celarius Banks female were solid refuges that can prevent several predator species from intruding. In addition to the above function, we found that once scattered nests have suffered predation, they then function as "dummies" to delude predators. Furthermore, most of them should invade the nests to search for and feed on eggs after nest detection. Namely, we indicated that these scattered void nests increase a predators searching cost (time), then function as "dummies for deluding predators" after suffering predation. Therefore, we could conclude that such predation pressure might operate as a disruptive selection pressure which caused the speciation of the celarius species group. In small beetles and ants, we also revealed several related phenomena and determined the phylogeny of them. These results have been prepared as 13 reports of which 4 reports had been accepted or published. The other 9 are now under submission.
Then, the present results strongly suggest that the predation pressure by multiple predators having various traits sometimes operate as very strong factors which cause the speciation of prey species through disruptive selection.
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