Y. Yamagishi et K. Kogame, FEMALE DOMINANT POPULATION OF COLPOMENIA-PEREGRINA (SCYTOSIPHONALES, PHAEOPHYCEAE), Botanica marina, 41(2), 1998, pp. 217-222
The ratio of fertile male to female gametophytes of Colpomenia peregri
na (Sauvageau) Hamel (Scytosiphonales, Phaeophyceae) was investigated
through its reproductive season at Oshoro in Hokkaido, Japan. It was a
bout 1:19 in the samples examined with determination by the size of ga
metangia. Thirty-three culture strains were established from sporophyt
ic discoid thalli collected from the field. Both female and male gamet
ophytes appeared in 10 strains of these cultures, and only female game
tophytes appeared in the remaining 23 strains. However, there was no s
train in which only male gametophytes appeared in culture. These 10 st
rains and 23 strains were considered to be derived from zygotic sporop
hytes and female parthenosporophytes, respectively. Germination of unf
used female and unfused male gametes was examined in culture. The abil
ity for germination was much lower in male gametes than that in female
gametes. Although, the cause of the female dominance of this species
at Oshoro was discussed considering the presence or absence of female-
like, asexual plants, the female dominance is chiefly due to the frequ
ent occurrence of parthenogenesis of female gametes.