title: Bimodal distribution of flowering time in a natural hybrid population of daylily (Hemerocallis fulva) and nightlily (Hemerocallis citrina).
abstract: Time of flower anthesis in a day is thought to evolve in response to the time of pollinator activities. We studied blooming and withering time in natural populations of daylily (Hemerocallis fulva), nightlily (Hemerocallis citrina) and their hybrids, and also in an artificially obtained array of the F1 hybrids. Blooming time of H. fulva varied from 4:30 to 7:30 and H. citrina varied from 16:30 to 20:30. In a natural hybrid population, blooming time and withering time showed discontinuous bimodal distribution in spite that morphological traits of flowers showed continuous unimodal variation. Most F1 hybrids showed diurnal flowering. These findings indicate that only a few genes have strong phenotypic effect on the determination of flowering time in Hemerocallis, and suggest that the evolution from a H. fulva-like ancestor to H. citrina was not a continuous process by accumulation of minute mutations.
authors.affiliation: Department of Biology, Faculty of Science, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hasegawa
authors.forename: Tetsukazu
authors.initials: T
authors.lastname: Yahara
authors.forename: Akiko
authors.initials: A
authors.lastname: Yasumoto
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Hotta
mesh_terms: D002940:Circadian Rhythm / Q000235:genetics / Q000502:physiology*; D035264:Flowers / Q000033:anatomy & histology / Q000502:physiology*; D049810:Genetic Speciation; D014644:Genetic Variation; D031421:Hemerocallis / Q000033:anatomy & histology / Q000235:genetics / Q000502:physiology*; D006824:Hybridization, Genetic; D018709:Statistics, Nonparametric