The parasite connection in ecosystems and macroevolution |
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Authors: | Adolf Seilacher Wolf-Ernst Reif Peter Wenk |
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Institution: | (1) Engelfriedshalde 25, 72076 Tuebingen, Germany;(2) Geology Department Yale University, POB 208109, New Heaven, CT 06520, USA;(3) Karolinenstift Pflegeheim, Melanchthonstr. 35, 72074 Tuebingen, Germany;(4) Falkenweg 69, 72076 Tuebingen, Germany |
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Abstract: | In addition to their obvious negative effects (“pathogens”), endoparasites of various kinds play an important role in shaping
and maintaining modern animal communities. In the long-term, parasites including pathogens are indispensable entities of any
ecosystem. To understand this, it is essential that one changes the viewpoint from the host’s interests to that of the parasite.
Together with geographic isolation, trophic arms race, symbiosis, and niche partitioning, all parasites (including balance
strategists, i.e. seemingly non-pathogenic ones) modulate their hosts’ population densities. In addition, heteroxenic parasites
control the balance between predator and prey species, particularly if final and intermediate hosts are vertebrates. Thereby,
such parasites enhance the bonds in ecosystems and help maintain the status quo. As the links between eukaryotic parasites
and their hosts are less flexible than trophic connections, parasite networks probably contributed to the observed stasis
and incumbency of ecosystems over geologic time, in spite of continuous Darwinian innovation. Because heteroxenic parasites
target taxonomic levels above that of the species (e.g. families), these taxa may have also become units of selection in global
catastrophies. Macroevolutionary extrapolations, however, are difficult to verify because endoparasites cannot fossilize. |
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Keywords: | Endemic evolution Coordinated stasis Mass extinctions Cyclic transmission Ediacara |
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