A Comparison of Adaptive Radiations of Antarctic
Fish with those of NonAntarctic Fish
Joseph T. Eastman 1 and Andrew Clarke 2
lDepartment of Biological Sciences, Ohio University, Athens, OH 45701, USA
2British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 OET, UK
Introduction
Antarctic biologists frequently emphasize the differences between the
modern Antarctic environment and its fauna, and aquatic habitats and
faunas elsewhere in the world. While it is valid to portray Antarctica as
remote and its fauna as endemic and cold adapted, this approach tends to
obscure broad scale similarities between Antarctic and non-Antarctic
faunas. For example, the Antarctic fish fauna shares an evolutionary
response to its habitat with fish in some tropical, temperate and boreal
lakes. In this review we compare some well studied lacustrine radiations of
fish with the two radiations of marine fish in the Antarctic Region of the
Southern Ocean, notothenioids and liparids. We shall first make the case
that, unlike other marine habitats, the Antarctic Region fulfills most of the
essential parameters of lakes containing radiations of fish and that this
large component of the world ocean is equivalent to a closed basin.
Therefore in spite of its vastness, the Antarctic Region provides a
comparable opportunity for studying evolutionary biology within a
confined area. It is likely that notothenioids, and possibly liparids, are the
first known examples of species flocks or radiations of marine fish. Thus
the high Antarctic shelf and upper slope is an insular evolutionary site,
with endemic faunas equally as interesting, but less well known, as those in
ancient lakes throughout the world.
We use recent information to compare Antarctic and non-Antarctic
radiations offish with respect to age of habitat, species diversity, molecular
divergence times, key innovations and degree of morphological and
ecological divergence with respect to phyletic divergence. Also of interest
are the geological, climatic and ecological factors that created the
conditions leading to these radiations. The radiation of notothenioid and
liparid fishes has taken place during a period of significant tectonic activity
and substantial climatic change [1-6]. Furthermore the evolutionary history
of one group, the notothenioids, has been elucidated by cladistic analyses
employing both morphological [1,7] and molecular [8,9] techniques.
Although the major features of the radiation of notothenioid fishes are now
G. di Prisco, E. Pisano, A. Clarke (Eds)
Fishes of Antarctica. A biological overview
© Springer-Verlag Italia 1998
Fish with those of NonAntarctic Fish
Joseph T. Eastman 1 and Andrew Clarke 2
lDepartment of Biological Sciences, Ohio University, Athens, OH 45701, USA
2British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 OET, UK
Introduction
Antarctic biologists frequently emphasize the differences between the
modern Antarctic environment and its fauna, and aquatic habitats and
faunas elsewhere in the world. While it is valid to portray Antarctica as
remote and its fauna as endemic and cold adapted, this approach tends to
obscure broad scale similarities between Antarctic and non-Antarctic
faunas. For example, the Antarctic fish fauna shares an evolutionary
response to its habitat with fish in some tropical, temperate and boreal
lakes. In this review we compare some well studied lacustrine radiations of
fish with the two radiations of marine fish in the Antarctic Region of the
Southern Ocean, notothenioids and liparids. We shall first make the case
that, unlike other marine habitats, the Antarctic Region fulfills most of the
essential parameters of lakes containing radiations of fish and that this
large component of the world ocean is equivalent to a closed basin.
Therefore in spite of its vastness, the Antarctic Region provides a
comparable opportunity for studying evolutionary biology within a
confined area. It is likely that notothenioids, and possibly liparids, are the
first known examples of species flocks or radiations of marine fish. Thus
the high Antarctic shelf and upper slope is an insular evolutionary site,
with endemic faunas equally as interesting, but less well known, as those in
ancient lakes throughout the world.
We use recent information to compare Antarctic and non-Antarctic
radiations offish with respect to age of habitat, species diversity, molecular
divergence times, key innovations and degree of morphological and
ecological divergence with respect to phyletic divergence. Also of interest
are the geological, climatic and ecological factors that created the
conditions leading to these radiations. The radiation of notothenioid and
liparid fishes has taken place during a period of significant tectonic activity
and substantial climatic change [1-6]. Furthermore the evolutionary history
of one group, the notothenioids, has been elucidated by cladistic analyses
employing both morphological [1,7] and molecular [8,9] techniques.
Although the major features of the radiation of notothenioid fishes are now
G. di Prisco, E. Pisano, A. Clarke (Eds)
Fishes of Antarctica. A biological overview
© Springer-Verlag Italia 1998