Genomic conflict over reproduction in a booklouse (Psocodea: Liposcelis): consequences of a maternally transmitted reproductive manipulator on host ecology and genetics

• Main Author: Hodson, Christina N.
• Other Authors: Perlman, Steven John
• Format: Others
• Language: English; en
• Published: 2016
• Subjects: biology; evolution; genomic conflict; reproduction; genetics
• Online Access: http://hdl.handle.net/1828/7007

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