Chapter 5
Metazoan Complexity
Florian Raible and Patrick R.H. Steinmetz
Abstract Evolution is often regarded as a process leading from simple ancestors to
more complex descendants, a generalized view that has also impacted on different
concepts of evolution. However, the study of new marine model systems, and the
inclusion of new levels of analysis, challenge this paradigm, as they reveal that levels
of complexity can diverge from the apparent organizational complexity of individual
species. In this chapter, we analyze molecular genetic progress from different animal
taxa, and how they help to determine the molecular changes associated with major
evolutionary transitions, such as the transition to multicellularity or the origin of
germ layers.
5.1 Approaches to Complexity
Haeckel’s lithograph “Stammbaum des Menschen” (“Pedigree of Man”) is a beautiful illustration of the concept of common evolutionary descent, and has widely been
adapted for the representation of animal phylogeny. In this tree, animal evolution
appears to progress steadily from “simple” life forms, such as “worms” (“vermes”),
at the bottom, to more “elaborate” forms, with mammals forming the crown of the
tree (Fig. 5.1). A similar trend can be found within the branches representing distinct animal phyla. For instance, “mud fish” are located close to the stem, whereas
teleosts are found at the tips, consistent with the intuitive notion that teleosts are
more “highly” evolved.
F. Raible (B)
Max F. Perutz Laboratories, Campus Vienna Biocenter, University of Vienna, A-1030 Vienna,
Austria
e-mail: florian raible@mfpl.ac.at
P.R.H. Steinmetz (B)
Department for Molecular Evolution and Development, University of Vienna, A-1090 Vienna,
Austria
e-mail: patrick.steinmetz@univie.ac.at
143
J.M. Cock et al. (eds.), Introduction to Marine Genomics,
Advances in Marine Genomics 1, DOI 10.1007/978-90-481-8639-6_5,
C
Springer Science+Business Media B.V. 2010
Metazoan Complexity
Florian Raible and Patrick R.H. Steinmetz
Abstract Evolution is often regarded as a process leading from simple ancestors to
more complex descendants, a generalized view that has also impacted on different
concepts of evolution. However, the study of new marine model systems, and the
inclusion of new levels of analysis, challenge this paradigm, as they reveal that levels
of complexity can diverge from the apparent organizational complexity of individual
species. In this chapter, we analyze molecular genetic progress from different animal
taxa, and how they help to determine the molecular changes associated with major
evolutionary transitions, such as the transition to multicellularity or the origin of
germ layers.
5.1 Approaches to Complexity
Haeckel’s lithograph “Stammbaum des Menschen” (“Pedigree of Man”) is a beautiful illustration of the concept of common evolutionary descent, and has widely been
adapted for the representation of animal phylogeny. In this tree, animal evolution
appears to progress steadily from “simple” life forms, such as “worms” (“vermes”),
at the bottom, to more “elaborate” forms, with mammals forming the crown of the
tree (Fig. 5.1). A similar trend can be found within the branches representing distinct animal phyla. For instance, “mud fish” are located close to the stem, whereas
teleosts are found at the tips, consistent with the intuitive notion that teleosts are
more “highly” evolved.
F. Raible (B)
Max F. Perutz Laboratories, Campus Vienna Biocenter, University of Vienna, A-1030 Vienna,
Austria
e-mail: florian raible@mfpl.ac.at
P.R.H. Steinmetz (B)
Department for Molecular Evolution and Development, University of Vienna, A-1090 Vienna,
Austria
e-mail: patrick.steinmetz@univie.ac.at
143
J.M. Cock et al. (eds.), Introduction to Marine Genomics,
Advances in Marine Genomics 1, DOI 10.1007/978-90-481-8639-6_5,
C
Springer Science+Business Media B.V. 2010