| Budget Amount *help |
¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1999: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1998: ¥800,000 (Direct Cost: ¥800,000)
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| Research Abstract |
This study aims to quantify the extent of inbreeding in a local population focusing on a pemphigid aphid in which selfing is readily forced. The method invented newly in this study made it possible not only to quantify the extent of inbreeding but also to estimate inbreeding depression. It has been inferred that the pemphigid aphid Prociphilus oriens is likely to inbreed in the field, based on the evidence of the sex ratio. However, the use of the present method clarified that this species has an outbreeding system. This result suggests that the sex ratio theory in aphids should be critically revised. In Prociphilus oriens, eggs from selfing, on the average, hatched later than those from outbreeding, when they were incubated under the same conditions. This later hatching can be considered as an inbreeding depression, because nymphs from late hatched eggs have morphological and physiological anomalies. However, when this method was applied to the non-host alternating aphid Kaltenbachiella japonica, selfing did not lead to later egg-hatching. The hatchability of selfed eggs did not differ significantly from that of outbred eggs either.
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