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A molecular phylogenetic study of the South American fish genus Pterophyllum

dc.contributor.advisorBellstedt, Dirk Uween_ZA
dc.contributor.authorAnderson, Chanelleen_ZA
dc.contributor.otherStellenbosch University. Faculty of Science. Dept. of Biochemistry.en_ZA
dc.date.accessioned2016-03-09T14:07:22Z
dc.date.available2017-12-31T03:00:07Z
dc.date.issued2016-03
dc.identifier.urihttp://hdl.handle.net/10019.1/98339
dc.descriptionThesis (MSc)--Stellenbosch University, 2016.en_ZA
dc.description.abstractENGLISH ABSTRACT: The South American fish genus Pterophyllum, commonly referred to as Angel Fish, contains three recognized species namely Pterophyllum leopoldi, Pterophyllum altum and Pterophyllum scalare. In addition, morphological variants, particularly of Pt. scalare and Pt. altum, occur in their natural habitat. However, uncertainty regarding the taxonomy and the phylogenetic relationships between the three species of the genus Pterophyllum within the tribe Heroini, still remains. In the first part of this study three mitochondrial (Cytochrome b, 16S rRNA and NADH dehydrogenase subunit 4) and two nuclear (Recombinase Activator Gene 2 and ribosomal S7 intron 1) markers were amplified and sequenced for 27 Pterophyllum samples. Along with this, 166 nucleotide reference sequences, representing six outgroups and 160 Neotropical cichlid taxa, were downloaded for each of the five molecular markers from GenBank. In addition to maximum likelihood and parsimony analyses, a BEAST analysis was performed on the Cytochrome b sequence matrix. This study was the first to conclusively show that the genus Pterophyllum is a monophyletic group of which Pt. leopoldi is the basal lineage whilst Pt. altum and Pt. scalare form a derived sister association. Furthermore, it appears that the evolution of the genus Pterophyllum corresponds to the historical geographical changes of the Amazonian landscape. In addition, the study also provides phylogenetic evidence for the reconnection of the Amazon and Orinoco river systems by means of the Casiquiare channel. In the second part of this study the sequence variability of 13 additional nuclear markers were investigated in order to expand the five-gene analysis with the aim of enhancing the resolution of the phylogeny. In conjunction with this, the number of Pterophyllum taxa included in the ND4 sequence matrix were increased from two to six representatives for each population of the three species in order to elucidate intraspecies and population variability. The two nuclear genes Mitfb and RpL8 were identified as the most variable of the 13 nuclear genes investigated. The inclusion of these two nuclear genes in the five-gene data matrix, improved the ratio of mitochondrial to nuclear variable characters from 79:21 to 67:33 in the seven-gene phylogeny. Distinction between Pt. altum of the upper Rio Negro and Upper Rio Orinoco was repeatedly confirmed with full statistical support. Variation within Pt. scalare retrieved three groups of which Pt. scalare Santa Isabel and Pt. scalare Manacapuru were the basal lineages. This study offers no phylogenetic evidence to support a hybrid origin for the latter.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Die Suid-Amerikaanse vis genus Pterophyllum, wat algemeen verwys word na as “Angelfish”, bevat tans drie herkende spesies naamlik Pterophyllum leopoldi, Pterophyllum altum en Pterophyllum scalare. Tans heers daar egter onsekerheid oor die taksonomiese posisie sowel as die filogenetiese verwantskappe tussen die drie spesies van die genus Pterophyllum, binne die tribus Heroini, aangesien morfologiese variante, veral van Pt. scalare en Pt. altum, in hul natuurlike habitat voorkom. In die eerste deel van hierdie studie was drie mitokondriale (Sitochroom b, 16S rRNS en NADH dehidrogenase subeenheid 4) en twee nuklêre (Rekombinasie Aktiveringsgeen 2 en ribosomale S7 intron 1) merkers vir 27 Pterophyllum monsters ge-amplifiseer en die nukleotied volgordes daarvan bepaal. Tesame hiermee was 166 nukleotied verwysingsvolgordes verteenwoordigend van ses buitegroep en 160 Neotropiese “cichlid” spesies vir elk van die vyf molekulêre merkers van GenBank afgelaai. Addisioneel tot “maximum likelihood” en “parsimony” analises, was ’n BEAST analise op slegs die Sitochroom b volgorde matriks uitgevoer. Hierdie studie was die eerste om onweerlegbaar te toon dat die genus Pterophyllum ’n monofiletiese groep vorm waarvan Pt. leopoldi basaal en Pt. altum en Pt. scalare in ’n afgeleide sister verhouding tot mekaar staan. Verder bleik die evolusie van die genus Pterophyllum ooreen te stem met die geskiedkundige geografiese veranderinge van die Amasone-streek. Daarmee saam bied die studie ook filogenetiese bewyse vir die heraansluiting van die Amasone en Orinoco rivier sisteme deur middel van die Casiquiare kanaal. In die tweede deel van hierdie studie was 13 addisionele nuklêre merkers se volgorde variabiliteit ondersoek ten doel die vyf-geen analise aan te vul om sodoende die resolusie van die filogenie te versterk. Terselfdertyd was die Pterophyllum taksa in die ND4 volgorde matriks uitgeberei van twee tot ses verteenwoordigers per populasie van elke spesie om sodoende intraspesies en populasie variabiliteit te ondersoek. Die twee nuklêre gene, Mitfb en RpL8, was as die mees variabele nuklêre gene geïdentifiseer. Die insluiting van hierdie twee gene by die vyf-gene data matriks het die verhouding mitochondriale tot nuklêre variabele karakters van 79:21 na 67:33 in die sewe-geen filogenie verbeter. Onderskeid tussen Pt. altum van die bo Rio Negro en bo Rio Orinoco kon herhaaldelik met volle statistiese steun bevestig word. Variasie binne Pt. scalare het drie groeperinge getoon waarvan die Pt. scalare Santa Isabel en Pt. scalare Manacapuru basale klades was. Die studie bied egter geen filogenetiese bewyse in steun van ’n hibried oorsprong vir laasgenoemdes.af_ZA
dc.format.extent166 pages : illustrations, mapsen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.subjectGenus Pterophyllumen_ZA
dc.subjectFish phylogenetics -- South Americaen_ZA
dc.subjectAngel fish (Pterophyllum) -- South Americaen_ZA
dc.subjectAngel fish (Pterophyllum) -- Phylogenetics scalareen_ZA
dc.subjectSouth American drainage patternsen_ZA
dc.subjectUCTDen_ZA
dc.titleA molecular phylogenetic study of the South American fish genus Pterophyllumen_ZA
dc.typeThesisen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.embargo.terms2017-12-31


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