Genomic conflict is pervasive in nature and affects a number of fundamental
evolutionary processes. Genomic conflict occurs when different genetic entities within a
species have different interests in terms of the optimal transmission strategy to future
generations, resulting in antagonistic interactions between these elements. When this
conflict is over the reproduction strategy within an individual, it can result in sex ratio
biases in an individual’s offspring. For instance, genomic conflict occurs between
maternally transmitted genetic elements (such as female limited chromosomes or
cytoplasmic elements) and nuclear elements over the optimal sex ratio of an individual’s
offspring due to the fact that maternally transmitted elements benefit from a female
biased sex ratio (as they are transmitted through the matriline) while nuclear elements
benefit from an equal sex ratio. I am investigating a maternally transmitted genetic
element in a sexual booklouse, Lipsocelis nr. bostrychophila (Insecta; Psocodea) that
manipulates reproduction such that all females carrying it produce exclusively female
offspring. This is expected to affect L. nr. bostrychophila evolution in a number of ways.
I investigated the ecology of L. nr. bostrychophila to gain a better understanding
of whether and how the selfish reproductive manipulator (designated the distorting
element) persists over time. I found that the distorting element is able to persist in L. nr.
bostrychophila populations, both in the wild and in the laboratory, and this is partially
due to the fact that females that carry the distorting element have a shorter lifespan and
do not produce as many offspring as females that do not carry the element. This helps to
counteract the advantage that females carrying the distorting element would otherwise
have due to the fact that they do not produce male offspring. Additionally, I found that
females that do not carry the distorting element also produce a female biased sex ratio.
This also likely mediates the persistence of the distorting element in wild and laboratory
L. nr. bostrychophila populations, and is particularly interesting in that I found that other
wild Liposcelis species also exhibit female biased sex ratios. This suggests that L. nr.
bostrychophila populations likely exhibited female bias sex ratios before the distorting
element arose in this species.
I also assessed the effect that the distorting element has had on the genomic
evolution of L. nr. bostrychophila. I found that females that carry the distorting element
have radically different mitochondria from females that do not carry it, leading me to
speculate that the reduced longevity in females that carry the distorting element may be a
consequence of impaired mitochondrial function. Finally, I found that all L. nr.
bostrychophila individuals have unusual mitochondria, with females that carry the
distorting element having five mitochondrial minichromosomes and females that do not
carry the distorting element having seven (rather than the single chromosome typical in
animals). These findings contribute to the growing body of evidence suggesting that
genomic conflict is an important force shaping species’ evolution, supporting the
importance of investigating the evolutionary forces at play within as well as between
individuals. / Graduate / 2018-12-16 / 0329 / 0369 / 0353
| Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/7007 |
| Date | 04 January 2016 |
| Creators | Hodson, Christina N. |
| Contributors | Perlman, Steven John |
| Source Sets | University of Victoria |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
| Rights | Available to the World Wide Web |
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