|
|
|
| Name |
| Viçoso, Beatriz |
|
| Nationality |
| Portuguese |
| E-Mail |
| bvicoso@ist.ac.at |
|
| 1st Degree |
| Genetics |
|
| University (1st Degree) |
| Universidade Federal do Rio de Janeiro |
|
| About the PhD |
| Field of Research |
| Evolution & Population Genetics |
|
| Thesis Title |
| X- chromosome evolution in Drosophila |
|
| Abstract |
| Although the X chromosome is usually similar to the autosomes in size, gene density and cytogenetic appearance, theoretical models predict that its hemizygosity in males may cause unusual patterns of evolution. The sequencing... |
| more |
| Although the X chromosome is usually similar to the autosomes in size, gene density and cytogenetic appearance, theoretical models predict that its hemizygosity in males may cause unusual patterns of evolution. The sequencing of several genomes has indeed revealed differences between the X chromosome and the autosomes in the rates of gene divergence, patterns of gene expression and rates of gene movement between chromosomes. In this thesis, I have attempted to investigate some of these patterns and their possible causes. The first two chapters consist of theoretical and empirical work intended to analyse the rates of evolution of coding sequences of X-linked and autosomal loci, with particular emphasis on faster-X evolution, the theory that more effective selection on the X can lead to higher rates of adaptive evolution on this chromosome. By analyzing X-linked and autosomal coding sequence in several species of Drosophila, we found some evidence for more effective selection on the X, particularly evident in the higher levels of codon usage bias detected at X-linked loci. We argue that this could be due to higher levels of recombination on the X chromosome increasing its effective population size (NeX) relative to the autosomal effective population size (NeA). To further investigate this hypothesis, we have modeled the effect of increased NeX/NeA on rates of evolution and confirmed that this can contribute to faster-X evolution. The last two chapters deal with the evolution of sex-biased genes and the possible causes for their differential accumulation on the X. We used EST data to create expression profiles for D. melanogaster male-, female- and unbiased genes. Our results suggest that the expression levels of sex-biased genes are incompatible with the accepted iii model of sex-biased gene evolution. We also show that the deficit of testis-expressed genes that is observed in Drosophila seems to be stronger for highly expressed genes. In fact, for very lowly expressed genes, we observe a small excess of testis-expressed genes on the X. We attempt to discuss this pattern in view of what is currently known about the evolution of sex-biased gene expression. |
| close |
|
|
| Supervisor(s) |
| Brian Charlesworth |
|
| Co-Supervisor(s) |
| Penelope Haddrill |
|
| University |
| University of Edinburgh |
|
| Laboratory |
| Charlesworth |
|
| Date of Thesis Defence |
| 2008-05-27 |
|
| After the PhD (Current Situation) |
| Position |
| Assistant Professor |
|
| Project |
| Sex-chromosome evolution in non-model species |
|
| Institution |
| IST Austria |
| View Institution website |
|
| City |
| Klosterneuburg/Vienna |
|
| Country |
| Austria |
|
|
| Relevant Publications |
|
Reversal of an ancient sex chromosome to an autosome in Drosophila
B Vicoso, D Bachtrog - Nature, 2013 |
|
Numerous Transitions of Sex Chromosomes in Diptera
B Vicoso, D Bachtrog - PLoS Biology, 2015 |
|
| Vicoso B, Charlesworth B (2006) Evolution on the X chromosome: unusual patterns and processes. Nat Rev Genet 7: 645?653. |
| View Publication |
|
| Vicoso, B., Haddrill, P.R., Charlesworth, B. (2008) A multi-species approach for comparing sequence evolution of X-linked and autosomal sites in Drosophila. Genetics Research, 90(5): 421-31. |
|
| Vicoso, B., Charlesworth, B. (2009) Recombination Rates May Affect the Ratio of X to Autosomal Non-coding Polymorphism in African Populations of Drosophila melanogaster. Genetics 10.1534/genetics.108.098004. |
|
| Vicoso B, Charlesworth B. The Deficit of Male-Biased Genes on the D. melanogaster X Chromosome Is Expression-Dependent: A Consequence of Dosage Compensation? J Mol Evol. 2009 |
|
| Vicoso, B., Charlesworth, B. EFFECTIVE POPULATION SIZE AND THE FASTER-X EFFECT: AN EXTENDED MODEL. Evolution 2009 |
| View Publication |
| Publications |
|
| Vicoso, B. and Bachtrog, D. Progress and prospects toward our understanding of the evolution of dosage compensation. CHROMOSOME RESEARCH 17: 585-602, 2009 |
|
| Mank, JE, Vicoso, B, Berlin, S, Charlesworth, B. Effective population size and the faster-X effect: empirical results and their interpretation. Evolution 64: 663–674, 2010 |
| View Publication |
|
| Vicoso, B. and Bachtrog, B. Lack of global dosage compensation in Schistosoma mansoni, a female-heterogametic parasite. Genome Biol Evol (2011) doi: 10.1093/gbe/evr010 |
| View Publication |
|
Sex-biased gene expression at homomorphic sex chromosomes in emus and its implication for sex chromosome evolution
B Vicoso, VB Kaiser, D Bachtrog - Proceedings of the National Academy of Sciences, 2013 |
|
Comparative sex chromosome genomics in snakes: differentiation, evolutionary strata, and lack of global dosage compensation
B Vicoso, JJ Emerson, Y Zektser, S Mahajan, D Bachtrog - PLoS biology, 2013 |
| Last Update |
| 2015-04-24 13:01:15 |
| The responsibility for this page contents is entirely of the student/alumnus. |
|
 |
|
 |
|
 |
|
 |
|
 |
|
 |
|
Program financially supported by
the National Foundation for
Science and Technology
|
|
 |
|
