〈総説〉
「豊年蟲 オオシロカゲロウ」研究の50年: 大量発生を引き起こす一斉羽化と地理的単為生殖
2020 年 23 巻 4 号 p. 119-131
詳細
2020 年 23 巻 4 号 p. 119-131
Ephoron of polymitarcyid mayflies in East Asia includes three species, E. shigae, E. limnobium, and E. eophilum, but the former two species are not separated on their molecular phylogenetic trees. All-female automictic parthenogenetic reproduction is known only in Japanese E. shigae in which bisexual and unisexual populations are distributed across Japan without any clear biogeographic boundaries. Population genetic structure studies show the parthenogenetic origin occurred only once in western Japan and then expanded all over Japan. In some rivers, both reproductive types coexist, and parthenogenetic females occupied the population within 20 years after unisexual introduction. Ephoron shigae has univoltine life cycles, and adults emerge synchronously in early autumn in bisexual or unisexual populations. It is a future problem for this ecologically interesting mayfly to inhabit the same rivers with both reproductive types.
