Taxonomy and population genetics of the flightless moth genus, Pringleophaga in the sub-Antarctic

Groenewald, Catharina Wilhelmina (2013-03)

Thesis (MSc)--Stellenbosch University, 2013.

Thesis

ENGLISH ABSTRACT: Sub-Antarctic Islands are of considerable conservation importance due to their high endemicity and unique ecosystems. Furthermore, the rich geological and glaciological histories of these islands provide a unique platform to study the biodiversity and biogeography of its biota. Sub-Antarctic islands are divided into three biogeographic regions; the South Indian Ocean Province includes the Prince Edward Islands, Îles Kerguelen, Îles Crozet, Heard Island and McDonald Island. One of the taxa that have long fascinated biogeographers and taxonomists alike is the flightless moth, genus Pringleophaga, which is endemic to the Kerguelen, Crozet and Prince Edward Islands. This study addressed three questions relating to the genus Pringleophaga at various spatial and evolutionary scales. The original Pringleophaga species' descriptions include only minor morphological differences between P. kerguelensis and P. marioni, with P. crozetensis being more diverse. Anomalies characterize their geographic distributions with P. kerguelensis recognized from Îles Kerguelen and Prince Edward but not from nearby Marion Island. Sequence data from two mitochondrial and two nuclear genes were compared for specimens from across Pringleophaga's range. Parsimony networks as well Bayesian topologies revealed three lineages which correspond to the species' morphological classification. Specimens from Îles Crozet (P. crozetensis) were not monophyletic. This may be because of misidentification of specimens or alternatively, highlight as yet undescribed diversity in the genus. Genetic data confirm the presence of P. marioni, but not P. kerguelensis, on Prince Edward Island. Marion Island’s rich glacial / volcanic history and complex geomorphology has been shown to affect the genetic structure of various arthropod species including springtails, mites and weevils. This study extends previous phylogeographic work by testing the spatial genetic structure in P. marioni in light of previous hypotheses including the recently described geological lineament. In addition to mitochondrial COI data, a species-specific microsatellite library was developed. Analyses of molecular variance indicated population differentiation across the lineament. Evidence for glacial refugia associated with the high elevated locality of Katedraalkrans was provided by high genetic diversity and little differentiation from other localities. The final part of the study was aimed at providing possible explanations behind the high abundance of P. marioni in Wandering Albatross nests compared to other plant communities. Caterpillars gain a thermal advantage from an occupied nest; hence the designation of Albatrosses as thermal ecosystem engineers. Three hypotheses were investigated: 1) Caterpillars or eggs being inadvertently added into the nest during nest construction; 2) Caterpillars moving into nests and 3) Females moths preferentially ovipositing in nests. A genetic relatedness approach comparing individuals from nests with surrounding vegetation showed that caterpillars from vegetation were, on average, more related than those taken from nests. Given the expected genetic relatedness outcomes, moth seeking out nests is the most likely outcome. Importantly, genetic data add information to a diverse array of other information on caterpillar and moth preferences, physiology and ecology. This study highlights the potential of genetic data to unravel various questions relating to species biogeography, especially when morphological variation is limited and complex; landscape genetics; and also aiding in our understanding of ecological processes.

AFRIKAANSE OPSOMMING: Sub-Antarktiese Eilande is van merkwaardige belang vir natuurbewaring te wyte aan hulle hoë inheemsheid en unieke ekosisteme. Daarbenewens, die ryk geologiese en glasiasie geskiedenis van hierdie eilande skep ‘n unieke platform vir studies oor die biodiversiteit en biogeografie van hulle biota. Sub-Antarktiese Eilande word verdeel in drie biogeografiese gebiede; die Suid Indiese Oseaan Provinsie sluit die Prince Edward, Kerguelen, Crozet, Heard en McDonald Eilande in. Een van die taxa wat biogeograwe en taksonome al vir n geruime tyd fasineer is die vluglose mot, genus Pringleophaga, wat endemies is tot die Kerguelen, Crozet en Prince Edward Eilande. Hierdie studie ondersoek drie vrae rakende die Pringleophaga genus op verskeie ruimtelike en evolusionêre vlakke. Die Pringleophaga spesies se beskrywings sluit in geringe morfologiese verskille tussen P. kerguelensis en P. marioni, met P. crozetensis meer divers. Anomalieë karakteriseer hulle geografiese verspeidings met P. kerguelensis teenwoordig op die Kerguelen eilandgroep en Prince Edward, maar nie op die naasliggende Marion Eiland nie. DNS volgorde data van twee mitochondriale en twee nukluêre gene is vergelyk tussen spesies van regoor Pringleophaga se verspreidingsgrense. Parsimoniese netwerke sowel as Bayesiaanse topologieë het drie afstammelinge onthul wat ooreenstem met die spesies se morfologiese klassifikasies. Individue van die Crozet eilandgroep (P. crozetensis) was nie monofileties nie. Dit kan toegeskryf word aan wanidentifisering van individue of alternatiewelik, beklemtoon die tans onbeskryfde diversiteit in die genus. Genetiese data bevestig die teenwoordigheid van P. marioni, maar nie P. kerguelensis, op die Prince Edward Eilande. Marion Eiland se glasiale / vulkaniese geskiedenis en komplekse geomorfologie het getoon om die genetiese struktuur van verskeie geleedpotige spesies te affekteer. Hierdie studie brei uit op vorige filogeografiese werk deurdat die ruimtelike genetiese struktuur van P. marioni getoets word in die lig van vorige hipoteses, insluitende die onlangs beskryfde geologiese lineament. Benewens mitochondriale COI data, is n spesie-spesifieke mikrosatelliet biblioteek ontwikkel. Molekulêre analises dui op populasie differensiasie oor die lineament. Bewyse vir die hoogliggende Katedraalkrans lokaliteit as ’n moontlike glasiale skuiling is verskaf deur sy hoë genetiese diversiteit en minimale differensiasie van die ander lokaliteite. Die finale afdeling was ten doel om moontlike verklarings te vind vir die hoë getalle P. marioni in Grootalbatros neste in vergelyking met ander plant-komplekse. Ruspes verkry n termiese voordeel binne ‘n besette nes; vandaar die benaming van albatrosse as termiese ekosisteem ingenieurs. Drie hipoteses word ondersoek: 1) Ruspes of eiers word onbewustelik tot neste toegedien tydens die bou van die nes; 2) Ruspes kruip in die neste in en 3) Motte lê eiers by voorkeur in neste. Genetiese verwantskap toetse wat individue van neste vergelyk met dié van omringende plantmateriaal, dui daarop dat individue vanuit plant-komplekse meer verwant is aan mekaar as individue vanuit neste. Gegewe die genetiese verwantskap resultate, is motte wat neste uitsoek die mees waarskynlike hipotese. Meer belangrik, die genetiese data dra by tot verskeie ander vorme van informasie rakende ruspe en mot voorkeure, hul fisiologie en ekologie. Hierdie studie beklemtoon die potensiaal van genetiese data om verskeie vrae rondom spesies se biogeografie, veral wanneer morfologiese variasie beperk of kompleks is; landskap genetika; en ekologiese prosesse te ontrafel.

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