Phylogeny of phylum Porifera

Gabud, Tea (2012) Phylogeny of phylum Porifera. Bachelor's thesis, Faculty of Science > Department of Biology.

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There is a strong tendency in science towards solving the evolutionary history of taxonomic ranks of all living (and known fossil) organisms. That complex task is assigned to phylogeny. The phylum Porifera - sponges - has turned out to be a very interesting group whose phylogeny has not yet been resolved despite more than hundred years of research and emergence of new scientific methods. From a historical point of view, morphology of spicules and overall skeleton shape as a whole had an important role in defining the early systematics of Porifera and it is not to be ignored even at this point in time. On the other hand, using morphology as the only key to assemble phylogeny was not sufficient. Appearing a bit later, cytology has brought novelty in approach and clear answers regarding some Poriferan genera. Also, it plays a very important role in studying sponges without spicules. In some cases cytology has proved to be more effective in yielding information than molecular phylogeny. Including secondary metabolites in analyses, although potentially useful, has shown to be rather difficult due to a great number of endosymbionts living in sponges. The development of molecular phylogeny methods in 1990's resulted with their wide use in research of Porifera. Still, many questions remain unanswered, especially regarding the class Demospongiae. These new methods have been less effective in search of connections among species that evolved rather quickly in an evolutionary sense of time and/or have separated early in the evolution. The problem most commonly arises from our inability to detect homoplasy (or orthologues) and a secondary character loss with certainty. A part of the solution is expected to be reached through inclusion of more carefully selected genes that carry useful phylogenetic information which would be included in the formation of a phylogenetic tree. In the end, problems of modern phylogeny cannot be solved with any unique method or single set of information. They have to be approached from a multidisciplinary point of view with rational use of as many methods/information as possible.

Item Type: Thesis (Bachelor's thesis)
Supervisor: Bakran-Petricioli, Tatjana
Date: 2012
Number of Pages: 14
Subjects: NATURAL SCIENCES > Biology
Divisions: Faculty of Science > Department of Biology
Depositing User: Silvana Šehić
Date Deposited: 20 Oct 2014 11:38
Last Modified: 20 Oct 2014 11:38

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