2005 Fiscal Year Final Research Report Summary
Speciation of phytophagous insects : Testing "Sympatric speciation via host race formation" hypothesis
| Project/Area Number |
14204081
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
系統・分類
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| Research Institution | Hokkaido University |
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Principal Investigator |
KATAKURA Haruo Hokkaido University, Faculty of Science, Professor, 大学院・理学研究科, 教授 (40113542)
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| Co-Investigator(Kenkyū-buntansha) |
AOTSUKA Tadashi Tokyo Metropolitan University, Faculty of Urban Liberal Arts, Associate Professor, 都市教養学部理工学系, 助教授 (40106604)
NAKANO Susumu Hiroshima Shudo University, Faculty of Human Environmental Studies, Professor, 人間環境学部, 教授 (70237337)
FUJIYAMA Naoyuki Hokkaido University of Education, Faculty of Education, Associate Professor, 教育学部, 助教授 (90360958)
KOBAYASHI Norio The Hokkaido University Museum, Research Staff, 総合博物館, 資料部研究員 (00400036)
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| Project Period (FY) |
2002 – 2005
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| Keywords | ecological speciation / epilachnine ladybird beetles / host specificity / reproductive isolation / quantitative genetics / DNA analyses / host race / East and southeast Asia |
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| Research Abstract |
We tested the hypothesis that phytophagous insects speciate sympatrically through an intermediate state called "host races," using epilachnine ladybird beetles and Chrysolina leaf beetles as the research materials. The main results are :
1. On the basis of various sorts of information we have demonstrated that two sympatric ladybird beetles, Henosepilachna niponica feeding on wild thistles (Cirsium spp., Asteraceae) and H.yasutomii, on blue cohosh (Caulophyllum robustum, Berberidaceae), are reproductively isolated by their fidelity to respective host plants. A comparison of this species pair and their northerly distributed sibling species H. pustulosa (occurring on both thistle and blue cohosh) suggests that the difference of life history traits, in particular phenological trait, might be important to account for the observed sympatric/allopatric relationships of these ladybird beetles. Furthermore, sympatric occurrence of H. niponica and H. yasutomii might be maintained by the selectio
… More
n against their hybrids that showed lower fitness than parents on either thistle or blue cohosh.
2. In Indonesia, Henosepilachna vigintioctopunctata, known as an important pest of solanaceous crops and weeds, is proven to be expanding their host plant range to cover an introduced weedy legume, Centrosema pubescens.
3. Another Indonesian species Henosepilachna sp. 3 is proven to be consisted of two host specific races, one on Mikania (Asteraceae) and another on Leucas (Labiatae). The two races are nearly completely reproductively isolated, and a mitochondrial analysis suggests that the two have diverged on the island of Java.
The results showed that the shift of host plants significantly influence the phytophagous insects both physiologically and ecologically, and immediately yields a very strong reproductive isolation between the population on the old host plant and that on the new host. The results suggest that the state of "host races" might be very short or even not realized during the host mediated speciation of phytophagous insects. Less
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