Biology Reference
In-Depth Information
Table 2 lists the lability of the sex differentiation process in selected fi shes,
in which sex reversal is/can be induced. The magnitudes of the lability
clearly show that the early stages of fi shes have retained bisexual potential
to differentiate either into male or female. However, it is diffi cult to reconcile
with differentiation in sex changing hermaphrodites. Incidentally, the term
sex change refers to the natural event of gender change in a fi sh and sex
reversal to artifi cially induced gender change. The wrong usage of terms
like 'natural sex inversion' (Kokokris et al., 2006), 'sex inversion' (Li et al.,
2006) and involution (Liarte et al., 2007) may be avoided.
Table 2.
Lability of sex differentiation of selected fi shes; the lability provides scope for (1)
ploidy, (2) endocrine, (3) thermal or (4) environmental (4a: pH, hypoxia, 4b: density or 4c:
surgical) manipulations. +* = all female brood, +** = all male brood, + = experimentally
proved amenable, - = experimentally proved not amenable or not known (from Pandian and
Koteeswaran, 1999, updated)
Family
Species
1
2
3
4a
4b
4c
Clarias gariepinus
Siluridae
+
+
-
-
-
-
C. lazera
-
+
+
-
-
-
Ictalurus punctatus
-
+
+
-
-
-
Anabantidae
Betta splendens
+
+
-
-
+
+
Trichogaster trichopterus
-
-
-
-
-
+
Macropodus opercularis
+
+
-
-
+
-
Oreochromis mossambicus
Cichlidae
+
+
+*
+
-
-
O. aureus
+
+
+**
-
-
-
O. niloticus
+
+
+
+
-
+
Tilapia macrocephalus
-
-
-
-
-
-
Salmonidae
Oncorhynchus mykiss
+
+
-
-
-
+
O. masou
+
+
-
-
-
-
Poecilidae
Poeciliopsis lucida
-
-
+
-
-
-
Poecilia reticulata
-
+
-
-
-
-
Cyprinus carpio
Cyprinidae
+
+
-
-
-
-
Danio rerio
+
-
-
+
-
-
Oryzias latipes
Adrianichthyidae
+
+
+*
-
-
+
Cobitidae
Misgurnus
anguillicaudatus
+
-
+*
-
-
-
Paralichthyidae
Paralichthys olivaceus
+
+
+*/+
-
-
-
Atherinidae
Odontesthes bonariensis
+
+
+
-
-
-
Patagonia hatcheri
-
-
+
-
-
-
Gonochores: Based on the presence or absence of a non functional
intersexual phase during ontogenetic pathway of sexual differentiation,
Yamamoto (1969) recognized two categories of sexual differentiation
patterns and named them as the primary and secondary gonochores.
Primary or differentiated gonochorism exists, when the differentiation
