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Doctoral defence of Annalaura Jokiniemi, MSc, 7.10.2022: Compatibility perspective on human mate choice and infertility

The doctoral dissertation in the field of Biology will be examined at the Faculty of Science and Forestry, Joensuu Campus and online. 

What is the topic of your doctoral research? Why is it important to study the topic?

My topic is mate choice in humans at both levels; before and after mating. My thesis focuses on the sperm selection occurring inside female's reproductive tract (called cryptic female choice). The topic is very relevant, because there are not many of the studies published, which are showing this phenomenon to be true also in humans. The results of my thesis will give more information of the sexual selection, which is a crucial mechanism of natural selection. We know also surprisingly little about the fertilization event itself, and my thesis supports the idea that fertilization is non-random event.

What are the key findings or observations of your doctoral research?

In my thesis, I show that cryptic female choice operates also in humans, and also that it is associated with immune genes (Human leukocyte Antigen, HLA). In other words, the more different the combination (male-female) was in their HLA genes, the better was the sperm performance. In my thesis spermatozoa were always activated in vitro with female reproductive tract liquids to mimic the environment prior to fertilization. The results of the studies revealed that sperm’s responsiveness to both female reproductive tract fluids was strongly affected by the male–female combination and the immunogenetic compatibility of the reproductive partners. Furthermore, the fusion of the gametes may be a highly selective process.

How can the results of your doctoral research be utilised in practice?

Overall, the results of my thesis increase our understanding of both pre- and post-mating sexual selection. Nowadays infertility can be treated with different assisted reproductive techniques, however incompatibilities behind the fertility issues should be better acknowledged.  The current definition of infertility ignores the possibility that there might be compatibility differences between reproductive partners. My thesis may also help to build a more comprehensive view of infertility, which could for example help to develop novel contraceptives or improve the treatments for infertility.

What are the key research methods and materials used in your doctoral research?

My thesis is done in the project, which Academy of Finland has granted for Associate Professor Jukka Kekäläinen. In the thesis, the gamete-level preferences were investigated by treating the spermatozoa of multiple males with female derived reproductive liquids (follicular fluid or cervical mucus) in all possible male–female combinations (full factorial experimental design). Samples were collected from the donors recruited from the infertility clinic of North Karelia central hospital.  The sperm’s responsiveness to the fluids from the female reproductive tract was determined by measuring sperm swimming velocity and sperm viability at different time points. Premating preferences of multiple women were investigated based on odour cues from the opposite sex. Furthermore, the interaction between pre- and post-mating selection episodes was studied to find out if odor pleasantness is associated with better sperm motility.

Is there something else about your doctoral dissertation you would like to share in the press release?

There was numerous of anonymous volunteer participants in the studies of this thesis, I would like to express my gratitude that they were willing to participate to the studies. Without their commitment making the research would have bon impossible. Collaborators in all the studies in my dissertation are North Karelia Central hospital and Finnish Red Cross Blood service.

The doctoral dissertation of Annalaura Jokiniemi, MSc, entitled Compatibility perspective on human mate choice and infertility, will be examined at the Faculty of Science and Forestry. The Opponent will be Associate Professor John Fitzpatrick, Stockholm University, Sweden, and the Custos will be Associate Professor Jukka Kekäläinen, University of Eastern Finland. Language of the public defence is English.

For more information, please contact:

Annalaura Jokiniemi, annalaura.jokiniemi@uef.fi, tel.+358 50 308 6929, Twitter: JokiniemiA