|| 要旨トップ | 本企画の概要 |||日本生態学会第57回全国大会 (2010年3月，東京) 講演要旨|
The major advantage of sexual reproduction is that it promotes genetic variability, despite the disadvantages of reduced genetic contribution to offspring and the cost of finding mates. Many termite species undergo royal succession, in which the primary reproductives who found colonies are replaced by secondary reproductives from within the nest. Under normal sexual reproduction, such a breeding system is expected to result in inbred colonies with limited genetic diversity. Recently, we found that the termite Reticulitermes speratus avoids inbreeding by the conditional use of parthenogenesis (Matsuura et al. 2009, Science). In mature field colonies, primary kings were present but primary queens had been replaced by an average of 55.4 secondary queens. Genetic analysis showed that secondary queens were exclusively produced parthenogenetically by the original primary queen, whereas workers and alates were produced by sexual reproduction and therefore retained levels of heterozygosity. By producing her replacements parthenogenetically, the queen maintains her full genetic contribution to the next generation of primary reproductives. These findings reveal a novel breeding system in which asexually produced replacement reproductives in colonies of a social insect are used to boost sexual reproductive output of the queen to the benefit of both the queen and the colony.