Biology Reference
In-Depth Information
A
B
Polymixia
Xenolepidichthys
Neocyttus
Cyttus
Zeus
Monodactylus
Trachinotus
Caranx
Scorpis
Platax
Chaetodipterus
14
100
100
1
1
61
59
3
5
57
1
2
8
78
1
†
Heteronectes
†
Amphistium
1
N =
1
L =
135
CI =
0.50
RI =
0.74
RCI =
0.37
Psettodes
1
2
6
61
87
81
†
Joleaudichthys
†
Numidiopleura
5
8
86
5
Tephrinectes
91
89
3
†
Eobothus
Citharus
83
81
62
51
C
Trachinotus
†
Amphistium/
†
Heteronectes
Psettodes
Citharus
Orbit eclipses dorsal midline
Orbital migration
= Migrated orbit
= Unmigrated orbit
Figure 6.10 Phylogenetic placement of Heteronectes and Amphistium and implications
for the origin of cranial asymmetry in flatfishes. (A) Topology arising from the analysis
of a matrix comprising 19 taxa coded for 58 morphological characters (8 ordered) (num-
ber of cladograms¼1; cladogram length¼135; consistency index¼0.50; retention
index¼0.74; rescaled consistency index¼0.37). Heteronectes and Amphistium are
placed as successively more crownward plesions on the flatfish stem. Unordered ana-
lyses reconstruct these taxa at the same position. Numbers at nodes indicate Bremer
decay index, bootstrap support, and jackknife support, from top to bottom, respectively.
Extinct taxa are marked (†) and “-” indicates that bipartition occurs in fewer than half of
cladograms arising from bootstrap or jackknife analysis. Previous placements of Amphi-
stiumoutside Pleuronectiformes are rejected. (B) Reconstruction of Amphistium, showing
sinistral (front) and dextral (back) individuals in the left lateral view (modified from
Blot,
1969
). (C) Simplified cladogram adapted from (A) showing the progression of orbital mi-
gration across flatfish phylogeny from adult specimens. Neurocrania are depicted in left
lateral (top), dorsal (middle), and right lateral (bottom) views. Reproduced with permission
from
Friedman (2008)
.
(
Aritaki & Seikai, 2004; Blanco-Vives et al., 2010
). The developmental pro-
cesses underlying abnormalities in metamorphic asymmetry likely originate
during embryogenesis or early larval development (
Power et al., 2008
), and
the identification of new molecular markers to differentiate normal from
abnormal developing larvae will be needed to further study the cause of
these abnormalities. Several molecular tools are now being developed and
