evolutionary studies of the ZW sex chromosome system in Salix viminalis
Pucholt, Pascal
(2016).
Sex chromosomes in willows.
Diss. (sammanfattning/summary)
Uppsala :
Sveriges lantbruksuniv.,
Acta Universitatis Agriculturae Sueciae, 1652-6880
; 2016:113
ISBN 978-91-576-8729-6
eISBN 978-91-576-8730-2
[Doctoral thesis]
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PDF
Available under License Creative Commons Attribution No Derivatives. 1MB |
Abstract
Sexual reproduction is found in most eukaryotes and has in the majority of animal species led to the evolution of separate sexes. In contrast, only 5-6% of all angiospersms are dioecious with female and male flowers on separate individuals. Interestingly, dioecy has evolved hundreds of times independently and at different timepoints in angiosperms. The development of separate sexes requires a sex determination mechanism, which often is located on sex chromosomes. The independent evolution of numerous sex determination and sex chromosome systems in angiosperms allows for studies of processes involved in different stages of their evolution. The ratio between male and female individuals in a dioecious population is expected to be equal due to frequency dependent selection. Distorted sex ratios are however common in many plant and animal species.
The overall aim of my thesis was to investigate the sex chromosome system in the dioecious, perennial willow species Salix viminalis that both in natural populations as well as in lab populations often displays female biased sex ratios. Although dioecy evolved from hermaphroditic ancestors before the split between Salix and its sister genus Populus, we found that the two lineages have different sex chromosomes (Populus: Chr. 19, Salix: Chr. 15). As we found no evidence for translocations between these chromosomes, it is most likely that two different sex determination mechanims are present in the two lineages, meaning that sex chromosome turnover has occurred recently. We furthermore determined that S. viminalis is female heterogametic (females Z/W, males Z/Z) and has a single sex determination locus on chromosome 15. The W homolog of the sex determination region contains hemizygous, female specific sequences and the SNP density in this region is increased in females relative to males, witnessing of lost recombination between the Z/W homologs. We did not find a Fast-Z effect or major degeneration of the W chromosome, suggesting a recent evolution. In fact this sex chromosome system is among the youngest observed so far. Based on our data, the insertion of repetitive sequence and sex specific gene expression appear to be among the first processes to happen in sex chromosome evolution.
We also determined that female biased sex ratios in S. viminalis are likely caused by an allelic incompatibility between Z homologs which results in the lack of one expected male genotype, reducing the male frequency in the population.
My studies thus extended our knowledge on processes involved in sex chromosome evolution and evolution of biased sex ratios in S. viminalis. However, given how common these phenomena are, results from my research can be applied to most organisms with genetic sex determination.
Authors/Creators: | Pucholt, Pascal | ||||||||||
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Title: | Sex chromosomes in willows | ||||||||||
Subtitle: | evolutionary studies of the ZW sex chromosome system in Salix viminalis | ||||||||||
Alternative abstract: |
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Series/Journal: | Acta Universitatis Agriculturae Sueciae (1652-6880) | ||||||||||
Year of publishing : | 11 November 2016 | ||||||||||
Number: | 2016:113 | ||||||||||
Number of Pages: | 71 | ||||||||||
Papers/manuscripts: |
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Place of Publication: | Uppsala | ||||||||||
Publisher: | Department of Plant Biology, Swedish University of Agricultural Sciences | ||||||||||
ISBN for printed version: | 978-91-576-8729-6 | ||||||||||
ISBN for electronic version: | 978-91-576-8730-2 | ||||||||||
ISSN: | 1652-6880 | ||||||||||
Language: | English | ||||||||||
Publication Type: | Doctoral thesis | ||||||||||
Copyright: | Creative Commons: Attribution-No Derivative Works 4.0 | ||||||||||
Full Text Status: | Public | ||||||||||
Agris subject categories.: | F Plant production > F30 Plant genetics and breeding F Plant production > F63 Plant physiology - Reproduction | ||||||||||
Subjects: | (A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Genetics (medical genetics to be 30107 and agricultural genetics to be 40402) (A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Bioinformatics and Systems Biology (methods development to be 10203) (A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Evolutionary Biology | ||||||||||
Agrovoc terms: | salicaceae, salix viminalis, sex chromosomes, sex determination, sex ratio, genomes, chromosomes, quantitative trait loci | ||||||||||
Keywords: | sex chromosomes, Salicaceae, sex determination, sex ratio, GWAS, QTL, GBS, Salix | ||||||||||
URN:NBN: | urn:nbn:se:slu:epsilon-e-3778 | ||||||||||
Permanent URL: | http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-3778 | ||||||||||
ID Code: | 13710 | ||||||||||
Faculty: | NJ - Fakulteten för naturresurser och jordbruksvetenskap | ||||||||||
Department: | (NL, NJ) > Department of Plant Biology (from 140101) | ||||||||||
Deposited By: | Pascal Pucholt | ||||||||||
Deposited On: | 10 Nov 2016 14:03 | ||||||||||
Metadata Last Modified: | 10 Sep 2020 13:41 |
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