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Selected Publication:

Type of publication: PhD Thesis
Type of document:

Year: 2012

Authors: Hopfen, Corinna

Title: Analysing the genetic basis of morphological variation in Drosophila.

Other title: Analyse der genetischen Grundlage morphologischer Variation in Drosophila

Source: PhD-Arbeit, Vet. Med. Univ. Wien, pp. 145.


Advisor(s):

McGregor Alistair
Schlötterer Christian

Reviewer(s):
Charlesworth Brian

Vetmed Research Units:
Institute of Population Genetics


Graduation date: 04.05.12


Abstract:
There is a long standing interest in evolutionary biology in investigating the genetics underlying morphological di erences. Thus far, considerable progress has been made in explaining the molecular mechanisms underlying morphological di erences in a number of species and in identifying candidate genes causing inter- and intraspecic trait variation. From this work general features of morphological evolution are beginning to emerge including the suggestion that cis-regulatory sequence evolution underlies most changes seen between species, whereas trans-regulatory changes may be more frequent within species. However, further studies of the genetic basis of more traits and comparing their regulation within and between species are required to test such hypotheses further. In this study, I investigated the genetic basis of di erences in eye and genital morphology within and among species of the Drosophila melanogaster species subgroup: D. melanogaster, D. simulans, D. sechellia and D. mauritiana. These species show remarkable variation regarding eye size and shape: For example, D. mauritiana has larger eyes especially in the dorsal region compared to the other species. In addition striking variation can be found in the male genitalia of these species. While a number of studies have investigated the underlying loci altering posterior lobe morphology little work has been done on the genetic architecture of other male genital traits, including the claspers and anal plates. I surveyed variation in the morphology of claspers and anal plates in di erent strains of D. mauritiana, D. simulans and D. sechellia. I found extensive intra- and interspeci c variation in clasper size and bristle number. To begin to map the causative loci, I then carried out QTL mapping of these traits in backcross progeny generated from crosses between D. mauritiana and D. simulans. I identi ed a major QTL region on the X chromosome and a region on the left arm of chromosome III (3L) to underly interspecifc di erences in genital morphology. I then carried out high resolution mapping by rst introgressing the 3L QTL region from D. mauritiana into the D. simulans genetic background and found this region to signi cantly alterclasper size and bristle number, anal plate size and posterior lobe shape. Subsequent nescale mapping revealed a variation in a smaller region of approximately 2 Mb is responsible, and this region contains a number of interesting candidate genes. Taken together my work will serve as a platform to compare the genetic basis of di erences in complex morphological traits like eye size and shape and genitalia, and therefore, address broader questions regarding the evolution of morphology.


Publication(s) resulting from University thesis:

Posnien, N; Hopfen, C; Hilbrant, M; Ramos-Womack, M; Murat, S; Schönauer, A; Herbert, SL; Nunes, MD; Arif, S; Breuker, CJ; Schlötterer, C; Mitteroecker, P; McGregor, AP (2012): Evolution of eye morphology and rhodopsin expression in the Drosophila melanogaster species subgroup. PLoS One. 2012; 7(5):e37346
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Janssen, R; Le Gouar, M; Pechmann, M; Poulin, F; Bolognesi, R; Schwager, EE; Hopfen, C; Colbourne, JK; Budd, GE; Brown, SJ; Prpic, NM; Kosiol, C; Vervoort, M; Damen, WG; Balavoine, G; McGregor, AP (2010): Conservation, loss, and redeployment of Wnt ligands in protostomes: implications for understanding the evolution of segment formation. BMC Evol Biol. 2010; 10:374
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Murat, S; Hopfen, C; McGregor, AP (2010): The function and evolution of Wnt genes in arthropods. Arthropod Struct Dev. 2010; 39(6):446-452

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