Sexual conflict and genome evolution in haplodiploid organisms

Supervisors: Laura Ross, Andy Gardner

Project description:

Sexual conflicts result from a clash of interests between the sexes [1]. In many cases, this battle is fought at the level of the gene: males and females may differ with respect to which version of a gene maximizes their Darwinian fitness. Whilst the effects of such intralocus sexual conflicts have been studied intensively in many organisms, the vast majority of studies have focused on species with classical, diploid sexual reproduction. However, as many as 15% of animal species exhibit an alternative, haplodiploid mode of inheritance. In such species, mothers monopolize the production of male offspring, either by asexual production of sons or by producing sons that eliminate their father’s genome after the zygote stage [2]. This asymmetrical mode of inheritance is likely to affect the outcome of intralocus sexual conflict. Specifically, as alleles that favour male fitness cannot be passed on directly from fathers to sons, sexual conflicts may be resolved in favour of females [2]. 

The aim of this project is to study the fate of alleles under intralocus sexual conflict in a range of haplodiploid taxa. Studying such exceptions to the general rules of reproduction provides illumination of the fundamental principles of evolutionary genetics (see [3] for a recent comparable example). This project will combine laboratory experiments, gene expression studies and genome analyses. We will focus particularly on springtails and fungus gnats, as males in these species carry and express their father’s genomes, but do not pass them on to their offspring. In addition, these species still retain recognizable sex chromosomes, which enables informative sex chromosome / autosome comparisons (e.g. [3]). These experimental approaches will be combined with comparative phylogenetic analyses and the development of novel evolutionary theory, according to the interests of the student. 

The project will be supervised by Dr. Laura Ross and Dr. Andy Gardner (St. Andrews). Ross is an evolutionary biologist who uses a combination of genomic, empirical and phylogenetic approaches to study the evolution and evolutionary consequences of different types of reproduction among the animal kingdom. Gardner is a leading mathematical biologist whose works spans a wide range of topics in theoretical biology and genetics. The proposed project strongly rest upon the collaboration between the supervisors as, on the one hand, formalization of the relevant theoretical hypotheses is currently lacking and, on the other hand, empirical work is required for estimation of key model parameters. The candidate will be based primarily in Edinburgh, as required by the empirical work, but will spend 1-2 days per month in St. Andrews for the duration of the project, as well as two 1-2 month intensive visits to the Gardner lab in years 2 and 3. 

For informal enquiries contact Dr Laura Ross.

References:

[1] Bonduriansky, Russell, and Stephen F. Chenoweth. "Intralocus sexual conflict." Trends in Ecology & Evolution 24.5 (2009): 280-288. 
[2] De la Filia, Andres G., Stevie A. Bain, and Laura Ross. "Haplodiploidy and the reproductive ecology of Arthropods." Current Opinion in Insect Science (2015). 
[3] Jaquiéry, Julie, et al. "Masculinization of the X chromosome in the pea aphid." Plos Genet 9 (2013): e1003690.

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