Gržan, Tena (2013) Evo-Devo. Bachelor's thesis, Faculty of Science > Department of Biology.

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Evo-Devo is a field of biology that compares the developmental processes of different organisms to determine the ancestral relationship between them, and to discover how developmental processes evolved. In this review I focused on a particular aspect within the field of Evo-Devo, which is the origin of the larva stage in ontogeny of some organisms. There are two hypotheses that dominate current opinion about this topic: the „larva-first“ and the intercalation hypotheses. Until recently, the „larva-first“ hypothesis was preeminent. This hypothesis implies that pre-bilaterian metazoans were small holoplanktonic creatures that swam and captured suspended food particles by using single ciliary band. This stem form gave rise to trochophore and dipleurula lineages, which each subsequently added a benthic stage to the life cycle. The second proposal for the origin of the pelago-benthic life cycle, the intercalation hypotesis, reconstructs the first bilaterians as holobentic organisms. These ancestral bilaterians secondarly acquired a planktonic larva when a stage of early development evolved cilia and became temporarily pelagic before returning to the benthos. The origin of indirect development is potentially an important topic for evolutionary biology, because if we decipher the origin of larvae in ontogeny of some organisms, we may be able to reconstruct the course of animal evolution, and the way it ran divergence of phylum.

Item Type: Thesis (Bachelor's thesis)
Supervisor: Franjević, Damjan
Date: 2013
Number of Pages: 27
Subjects: NATURAL SCIENCES > Biology
Divisions: Faculty of Science > Department of Biology
Depositing User: Silvana Šehić
Date Deposited: 15 Oct 2014 12:03
Last Modified: 15 Oct 2014 12:03
URI: http://digre.pmf.unizg.hr/id/eprint/3073

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