Identification and characterization of meiotic drive within the Drosophila virilis subgroup
There is a vast diversity of karyotypes in nature, yet mechanisms that have facilitated such diversity are unclear. Alterations to an organism’s karyotype can have major negative fitness consequences in meiosis through non-disjunction and aneuploidy. Here, I investigated the role of biased segregati...
Main Author: | |
---|---|
Other Authors: | |
Format: | Others |
Language: | English |
Published: |
University of Iowa
2017
|
Subjects: | |
Online Access: | https://ir.uiowa.edu/etd/5858 https://ir.uiowa.edu/cgi/viewcontent.cgi?article=7336&context=etd |
id |
ndltd-uiowa.edu-oai-ir.uiowa.edu-etd-7336 |
---|---|
record_format |
oai_dc |
spelling |
ndltd-uiowa.edu-oai-ir.uiowa.edu-etd-73362019-10-13T04:27:57Z Identification and characterization of meiotic drive within the Drosophila virilis subgroup Stewart, Nicholas There is a vast diversity of karyotypes in nature, yet mechanisms that have facilitated such diversity are unclear. Alterations to an organism’s karyotype can have major negative fitness consequences in meiosis through non-disjunction and aneuploidy. Here, I investigated the role of biased segregation in female meiosis, i.e., meiotic drive, as a force that contributes to the evolution of karyotype form. The closely related species pair, Drosophila americana and Drosophila novamexicana, is an exemplar for understanding mechanisms of karyotype evolution. Since their recent divergence nearly half a million years ago, D. americana has evolved two different centromeric fusions: one fusion between the 2nd and 3rd chromosomes (Muller elements C and D), and the other fusion between the X and 4th chromosomes (Muller elements A and B). The 2-3 fusion is fixed in D. americana. However, the X-4 centromeric fusion remains polymorphic within the species. I uncovered biased transmissions for both fused chromosomes in D. americana such that the X-4 fused chromosome was inherited by 57% of the offspring from heterozygous females and the 2-3 chromosome was inherited by 62% of the offspring. Introgression experiments shoed the fused X-4 and the unfused X and 4th chromosomes are segregating at a 50/50 ratio in D. novamexicana. I have isolated the fused X-4 centromeric region as a possible player in the observed meiotic drive. However, the centromere is not sufficient to cause meiotic drive without a secondary factor. I also measured heterochromatin content between the fused and unfused X and 4th homologs. No obvious size differences were uncovered, but possible compositional differences were revealed. This suggests that if the centromere itself is involved in meiotic drive, either differences in the number of centromeres or compositional differences between the centromeres are influencing meiotic drive. Overall, I have identified and characterized meiotic drive as a force driving karyotype evolution in D. americana but appears to be absent in D. novamexicana, and I have begun to dissect the mechanisms of meiotic drive. 2017-08-01T07:00:00Z dissertation application/pdf https://ir.uiowa.edu/etd/5858 https://ir.uiowa.edu/cgi/viewcontent.cgi?article=7336&context=etd Copyright © 2017 Nicholas Stewart Theses and Dissertations eng University of IowaMcAllister, Bryant F. Drosophila americana karyotype evolution Meiotic drive Biology |
collection |
NDLTD |
language |
English |
format |
Others
|
sources |
NDLTD |
topic |
Drosophila americana karyotype evolution Meiotic drive Biology |
spellingShingle |
Drosophila americana karyotype evolution Meiotic drive Biology Stewart, Nicholas Identification and characterization of meiotic drive within the Drosophila virilis subgroup |
description |
There is a vast diversity of karyotypes in nature, yet mechanisms that have facilitated such diversity are unclear. Alterations to an organism’s karyotype can have major negative fitness consequences in meiosis through non-disjunction and aneuploidy. Here, I investigated the role of biased segregation in female meiosis, i.e., meiotic drive, as a force that contributes to the evolution of karyotype form. The closely related species pair, Drosophila americana and Drosophila novamexicana, is an exemplar for understanding mechanisms of karyotype evolution. Since their recent divergence nearly half a million years ago, D. americana has evolved two different centromeric fusions: one fusion between the 2nd and 3rd chromosomes (Muller elements C and D), and the other fusion between the X and 4th chromosomes (Muller elements A and B). The 2-3 fusion is fixed in D. americana. However, the X-4 centromeric fusion remains polymorphic within the species. I uncovered biased transmissions for both fused chromosomes in D. americana such that the X-4 fused chromosome was inherited by 57% of the offspring from heterozygous females and the 2-3 chromosome was inherited by 62% of the offspring. Introgression experiments shoed the fused X-4 and the unfused X and 4th chromosomes are segregating at a 50/50 ratio in D. novamexicana. I have isolated the fused X-4 centromeric region as a possible player in the observed meiotic drive. However, the centromere is not sufficient to cause meiotic drive without a secondary factor. I also measured heterochromatin content between the fused and unfused X and 4th homologs. No obvious size differences were uncovered, but possible compositional differences were revealed. This suggests that if the centromere itself is involved in meiotic drive, either differences in the number of centromeres or compositional differences between the centromeres are influencing meiotic drive. Overall, I have identified and characterized meiotic drive as a force driving karyotype evolution in D. americana but appears to be absent in D. novamexicana, and I have begun to dissect the mechanisms of meiotic drive. |
author2 |
McAllister, Bryant F. |
author_facet |
McAllister, Bryant F. Stewart, Nicholas |
author |
Stewart, Nicholas |
author_sort |
Stewart, Nicholas |
title |
Identification and characterization of meiotic drive within the Drosophila virilis subgroup |
title_short |
Identification and characterization of meiotic drive within the Drosophila virilis subgroup |
title_full |
Identification and characterization of meiotic drive within the Drosophila virilis subgroup |
title_fullStr |
Identification and characterization of meiotic drive within the Drosophila virilis subgroup |
title_full_unstemmed |
Identification and characterization of meiotic drive within the Drosophila virilis subgroup |
title_sort |
identification and characterization of meiotic drive within the drosophila virilis subgroup |
publisher |
University of Iowa |
publishDate |
2017 |
url |
https://ir.uiowa.edu/etd/5858 https://ir.uiowa.edu/cgi/viewcontent.cgi?article=7336&context=etd |
work_keys_str_mv |
AT stewartnicholas identificationandcharacterizationofmeioticdrivewithinthedrosophilavirilissubgroup |
_version_ |
1719264529994481664 |