Four Years in Notothenioid Systematics:
A Molecular Perspective
Luca Bargelloni i and Guillaume Lecointre 2
iDipartimento di Biologia, Universita di Padova, via U. Bassi, 58/B
35131 Padova, Italy
2Service de systematique moleculaire et Laboratoire d'Ichtyologie, Museum
National d'Histoire Naturelle, 43 rue Cuvier, 75231 Paris Cedex 05, France
Why Notothenioids?
The perciform suborder Notothenioidei is a highly diversified group of
fish inhabiting the waters around the Antarctic continent. This is a unique
environment, characterized, especially in the high Antarctic Zone, by
temperatures as low as -2 °e, presence of sea ice, and large seasonal
fluctuations of the primary production. At the Oligocene-Miocene
boundary, about 25-22 million years ago, with the opening of the Drake
Passage and the formation of a circumpolar hydrographic barrier, the
Polar Front Zone, the Antarctic marine environment became effectively
isolated.
This isolation ireatly limited migration, therefore forcing the shallowwater fish fauna either to adapt to the harsh environmental conditions or to
become extinct. Notothenioids were able to survive and successfully
occupied a large variety of ecological niches. In terms of numbers of
species and biomass, they represent the dominant element of the Antarctic
fish fauna [1]. Notothenioids also show a remarkable degree of endemism
(97% of the species), and are distributed nearly exclusively in the
Antarctic marine waters. Compared to all the other groups of fishes in
Antarctica, notothenioids evolved several, remarkable adaptations to the
Antarctic conditions. Among the physiological and molecular adaptations
displayed by notothenioid fish, the most striking one is certainly the
presence of the antifreeze glycopeptides (AFGPs) which are responsible
for the depression of the freezing point [2].
Also some relevant physiological features, such as blood viscosity,
oxygen transport and cardiovascular system, significantly differ in these
fishes compared with temperate species [3]. In some Antarctic species
hemoglobins have reduced affinity for oxygen; the extreme case is
represented by the icefish (family Channichthyidae) that lacks
G. di Prisco, E. Pisano, A. Clarke (Eds)
Fishes of Antarctica. A biological overview
© Springer-Verlag Italia 1998
A Molecular Perspective
Luca Bargelloni i and Guillaume Lecointre 2
iDipartimento di Biologia, Universita di Padova, via U. Bassi, 58/B
35131 Padova, Italy
2Service de systematique moleculaire et Laboratoire d'Ichtyologie, Museum
National d'Histoire Naturelle, 43 rue Cuvier, 75231 Paris Cedex 05, France
Why Notothenioids?
The perciform suborder Notothenioidei is a highly diversified group of
fish inhabiting the waters around the Antarctic continent. This is a unique
environment, characterized, especially in the high Antarctic Zone, by
temperatures as low as -2 °e, presence of sea ice, and large seasonal
fluctuations of the primary production. At the Oligocene-Miocene
boundary, about 25-22 million years ago, with the opening of the Drake
Passage and the formation of a circumpolar hydrographic barrier, the
Polar Front Zone, the Antarctic marine environment became effectively
isolated.
This isolation ireatly limited migration, therefore forcing the shallowwater fish fauna either to adapt to the harsh environmental conditions or to
become extinct. Notothenioids were able to survive and successfully
occupied a large variety of ecological niches. In terms of numbers of
species and biomass, they represent the dominant element of the Antarctic
fish fauna [1]. Notothenioids also show a remarkable degree of endemism
(97% of the species), and are distributed nearly exclusively in the
Antarctic marine waters. Compared to all the other groups of fishes in
Antarctica, notothenioids evolved several, remarkable adaptations to the
Antarctic conditions. Among the physiological and molecular adaptations
displayed by notothenioid fish, the most striking one is certainly the
presence of the antifreeze glycopeptides (AFGPs) which are responsible
for the depression of the freezing point [2].
Also some relevant physiological features, such as blood viscosity,
oxygen transport and cardiovascular system, significantly differ in these
fishes compared with temperate species [3]. In some Antarctic species
hemoglobins have reduced affinity for oxygen; the extreme case is
represented by the icefish (family Channichthyidae) that lacks
G. di Prisco, E. Pisano, A. Clarke (Eds)
Fishes of Antarctica. A biological overview
© Springer-Verlag Italia 1998