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Selected Publication:

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Type of publication: PhD Thesis
Type of document:

Year: 2013

Authors: Kapun, Martin

Title: The genetic basis of adaptive evolution in Drosophila melanogaster.

Other title: Die genetischen Grundlagen evolutinärer Anpassung bei Drosophila melanogaster

Source: PhD-Arbeit, Vet. Med. Univ. Wien, pp. 157.


Advisor(s):

Schlötterer Christian

Reviewer(s):
Morgan, TJ
Flatt Thomas

Vetmed Research Units:
Institute of Population Genetics


Graduation date: 27.05.13


Abstract:
Understanding patterns of adaptation is one of the most fundamental goals in evolutionary biology. In this Ph.D. thesis I present three projects that address this fundamental question. Two studies exploit the power of next generation sequencing (NGS) technology by performing genome-wide analyses of fruit fly (Drosophila melanogaster) populations to identify patterns of selection. In the first study, we compared three populations collected along a latitudinal gradient along the North American east coast and identified SNP candidates that are likely indirect or direct targets of spatially varying selection. We found numerous candidate genes and pathways associated with clinally varying traits. In the second, study we performed a laboratory natural selection experiment, where we exposed fruit flies freshly sampled from a Portuguese population to a novel, fluctuating thermal laboratory regime. Using NGS we compared the genetic composition of our experimental evolution populations at multiple time-points, thus allowing us to follow allele frequency trajectories at potential candidate loci throughout the experiment. Notably, in both projects, we observed that in most comparisons candidates were strongly overrepresented on the right arm of the third chromosome (3R), especially in the region spanned by In(3R)Payne, a major cosmopolitan inversion. Using molecular markers, we identified a pronounced clinal distribution of this inversion in the latitudinal populations and a constant decrease in inversion frequency during the selection experiment. In(3R)Payne may thus be strongly affected by selection and may have a strong impact on genetic variation in this region. Finally, in the third project, we studied genetic variation and the host range of the Drosophila C Virus (DCV), a common and severe Drosophila pathogen. Using reverse transcription polymerase chain reaction (RT-PCR) and Sanger sequencing, we were able to detect DCV in six previously unknown host species. Furthermore, genetic variation among DCV samples did not cluster according to phylogeny or the geographical origin of the corresponding hosts, which suggest that co-evolution between D. melanogaster and DCV is very limited and gene flow is common. In summary, the three projects discussed in this Ph.D. thesis made use of state-of-the-art genomic and evolutionary methods aimed to address a fundamental question in evolutionary biology: the genetic basis of adaptation. The principal findings complement and extend our understanding of the evolutionary genetics of adaptation and provide a solid basis for future follow-up work.


Publication(s) resulting from University thesis:

Fabian, DK; Kapun, M; Nolte, V; Kofler, R; Schmidt, PS; Schlötterer, C; Flatt, T (2012): Genome-wide patterns of latitudinal differentiation among populations of Drosophila melanogaster from North America. Mol Ecol. 2012; 21(19):4748-4769
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Orozco-terWengel, P; Kapun, M; Nolte, V; Kofler, R; Flatt, T; Schlötterer, C (2012): Adaptation of Drosophila to a novel laboratory environment reveals temporally heterogeneous trajectories of selected alleles. Mol Ecol. 2012; 21(20):4931-4941
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Kapun, M; Nolte, V; Flatt, T; Schlötterer, C (2010): Host range and specificity of the Drosophila C virus. PLoS One. 2010; 5(8):e12421
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