Phylostratigraphic analysis of evolutionary emergence of organ systems in multicellular animals

Organski sustavi kod životinja oblikovani su adaptacijama na razini makroevolucijskih procesa. Tradicionalno, makroevolucijske procese proučavaju paleontologija, komparativna morfologija i evolucijska razvojna biologija (tzv. "evo-devo" pristup). Komparativna genomika otvara mogućnost novih razina analize makroevolucijskih trendova. Genomska filostratigrafija je inovativni pristup unutar ovog područja, kojim se otvara mogućnost otkrivanja tragova važnih adaptivnih događaja u evoluciji. Ovaj rad usredotočuje se na filostratigrafsku analizu organskih sustava kod životinja. U tu su svrhu analizirani genomski i ekspresijski podaci vinske mušice (Drosophila melanogaster). Rezultati ukazuju kako je neki oblik središnjeg živčanog sustava postojao kod pretka Eumetazoa. Također, podaci podupiru prisutnost primitivnog oblika srca kod pretka Bilateria. Analize trahealnog sustava daju potporu mogućem zajedničkom podrijetlu traheja kukaca i škrga rakova. Zanimljivo, filostratigrafski signal za probavni sustav prisutan je već kod pretka Metazoa. Ovaj rad pokazao je da se filostratigrafija može upotrijebiti u makroevolucijskoj analizi složenih fenotipova, kao što su organski sustavi. Međutim, za potpunije razumijevanje njihove evolucije potrebna je dostupnost većeg broja sekvenciranih genoma, kao i boljih ekspresijskih podataka.Organ systems in animals were shaped by adaptive processes on a macroevolutionary scale. Traditionally, macroevolution is in the scope of palaeontology, comparative morphology and evolutionary developmental biology (the so-called „evo-devo“ approach). Comparative genomics provides new levels of the analysis of macroevolutionary trends. Genomic phylostratigraphy is an innovative approach in this area of research, that could be used to trace important adaptive events in evolution. In the focus of this study is the phylostratigraphic analysis of organ systems in animals. For this purpose genomic and expression data from fruit fly (Drosophila melanogaster) was analyzed. Data suggest that some sort of central nervous system might be present in the eumetazoan ancestor. Also, support was found for the existence of a primitive form of heart in the bilaterian ancestor. Tracheal system analyses point to a possible common origin of tracheae and gills in the common ancestor of crustaceans and insects. Interestingly, a phylostratigraphic signal for the intestinal system is already present in the common ancestor of Metazoa. This work shows that phylostratigraphy could be effectively used in macroevolutionary analyses of complex phenotypes, such as organ systems. However, for a more complete understanding of their evolution, availability of a greater number of sequenced genomes, as well as more complete expression data, would be needed