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(Liu and Sadovy de Mitcheson, 2009). Within the 27 families, in which
functional hermaphroditism is confi rmed, it occurs in at least 6% of all
these families and more than 10% of families among the Perciformes.
Nevertheless, there are only 123 fi sh species in which natural sex change
occurs once or more than once during their life time; yet they constitute a
biologically fascinating group (Pandian, 2010) and commercially important
resource (Chopelet et al., 2009). Among these 123 species (Table 25), 74% of
them are protogynous hermaphrodites, clearly indicating that this pattern
Table 25.
Taxonomic distribution of different patterns of functional hermaphroditism
in fi shes, in which the indicated pattern of functional hermaphroditism is confi rmed or
suspected*/almost confi rmed (compiled from Sadovy de Mitcheson and Liu 2008)
Order
Simultaneous (no)
Protogyny (no)
Protoandry (no)
Serial (no)
Anguilliformes
Muraenidae
1
+
3*
-
Stomiformes
-
-
1
+
, 2*
-
Aulopiformes
7
+
, 2*
-
-
-
Cyprinodontiformes
1
+
, 1*
-
-
-
Synbranchiformes
-
3
+
-
-
Scorpaeniformes
-
3
+
5
+
1*
Perciformes
5
+
, 5*
71
+
, 17*
19
+
, 2*
7
+
, 4*
Total
14
+
, 8*
77
+
, 17*
25
+
, 7*
7
+
, 5*
of sequential hermaphroditism has been the choice of natural selection; the
choice of natural selection decreases in the order of : < protandry (20%) <
serial (6%). The geographical distribution of these hermaphrodites is limited
mostly to the tropical coral reef ecosystem. Except for a few species of
Amphiprion
that have been successfully cultured on a commercial scale in a
few countries (e.g., Ajith Kumar and Balasubramanian, 2009), the sequentials
and serials are not easily amenable to culture and/or maintained in the
laboratory. Consequently, literature available on their sex determination and
differentiation is far less, in comparison to that for gonochores. Hence the
description on the amazing diversity of these hermaphrodites is likely to be
more biological, and shall serve to introduce them to molecular biologists
in search of sex determining and differentiation genes.
3.2 Simultaneous hermaphrodites
By number of species, the simultaneous hermaphrodites are a few but in terms
of diversity, they fall under three patterns: 1. Self-fertilizing hermaphrodites,
2. Gamete exchange hermaphrodites, 3a. Marian hermaphrodites and 3b.
Okinawan hermaphrodites (Fig. 39). Self-fertilizing hermaphroditism, a
rarity among vertebrates, occurs in rivulus
Kryptolabias marmoratus
and
possibly in
K. ocellatus
(see Pandian, 2011); in them 98 and 97% self fertilization
