In this study, we have investigated the comparative performance of tamoxifen and letrozole on sex determination in a gonochorist cichlid O.
Paul-Prasanth B, Bhandari RK, Kobayashi T, Horiguchi R, Kobayashi Y (2013) Estrogen oversees the maintenance of the female genetic program in terminally differentiated gonochorists.
This is a slightly misleading interpretation in an undifferentiated gonochorist
species such as the zebrafish, because males that have arrested sexual differentiation, while superficially resembling early ovary type tissue (as do both sexes at this stage), do not develop into functional females and their gonads will differentiate into testes when removed from exposure (Hill and Janz 2003).
floridanus are gonochorist
(separate sexes: Bauer and VanHoy, 1996).
However, a recent study of the green humphead parrotfish (Bolbometopon muricatum) has emphasised that a definitive conclusion as to whether certain species in this family are protogynous hermaphrodites or gonochorists
can be difficult to ascertain, even when there is detailed information on such features as the size compositions of the two sexes and the histological characteristics of their gonads (Hamilton et al.
The sexuality of pectinids ranges from strictly gonochorists
to functional hermaphrodites (Coe 1945, Reddiah 1962), and there are 2 types of follicular structure in hermaphroditic specimens (Coe 1945, Reddiah 1962, Gaspar-Soria et al.
A three-year study (1998-2000) into its reproductive biology within the Tsitsikamma National Park revealed that these fishes are serial spawning late gonochorists.
as hermaphrodites) they mature as either a male or female (Table 1) and are therefore late gonochorists (rudimentary hermaphrodites).
Simultaneous hermaphrodites may evolve harmful male behavior more readily man gonochorists if the paternity advantage conferred upon the male function offsets the fecundity loss in the female function (Michiels and Koene, 2006).
Sexual selection favors harmful mating in hermaphrodites more than in gonochorists.
Our analyses, based on species that are sequential (1) or simultaneous (7) hermaphrodites, and gonochorists (10), suggest that, regardless of the placement of the root, the change from one strategy to the other has taken place only once within the group (Fig.
The "labronica" group of sibling species consists of gonochorists with the K-type of jaws; it is well supported by the analysis presented here and represents clade B in Figure lA.