PhD trial lecture and public defence: Torvald B. Egeland

14 December 2017 10:15 - 14 December 2017 15:30

Auditorium Petter Thomassen (A5)

PhD candidate Torvald B. Egeland will hold a trial lecture and defend his thesis for the degree Philosophiae Doctor (PhD), at the Faculty of Biosciences and Aquaculture, Nord University.

PhD-candidate: Torvald B. Egeland

Title of thesis:
Reproduction in Arctic charr - timing and the need for speed

Title of trial lecture:
Understanding the diversity of fish mating systems

Time of trial lecture: 10:15 - 11:15
Time of defence: 12:15 - 15:30
Place: Auditorium Petter Thomassen (A5)

Members of the evaluation committee:
Senior Researcher Francisco Garcia-Gonzalez, Donana Biological Station – Spanish Research Council, Sevilla, Spain
- Senior Researcher Elisabet Forsgren, Norwegian Institute for Nature Research (NINA – Norsk institutt for naturforskning), Trondheim
Associate Professor Torstein Kristensen, FBA, Nord University (leader)

Main supervisor: Professor Jarle Tryti Nordeide, FBA
Co-supervisor: Associate professor Einar Skarstad Egeland, FBA
Professor Ivar Folstad, University of Tromsø

The PhD trial lecture and defence are open to the public. The thesis is available on request. Please contact Jeanett Stegen,, phone: 75 51 74 49 

About the thesis:
The race towards the micropyle: For Arctic charr, male's reproduction is all about timing and the need for speed.

There is an intensive competition between males with different reproductive tactics on the spawning ground. The first part of the competition is position based, where the goal is to spawn in synchrony with the female. The second part is sperm competition, where sperm from different males race towards the micropyle – the egg entrance. The thesis describes the males behaviour before spawning and investigate which factors are important in sperm competition after spawning.

Arctic charr males have two alternative reproductive tactics, guarding males and sneaker males. The guarding male has an advantage in the position based competition before spawning, and he spawns more in synchrony with the female. However, fertilization trails show that the sneaker males can compensate for their disadvantages by producing sperm that swim faster. Sperm swimming speed is the most important factor predicting the outcome of sperm competition. 

By activating sperm in water and in ovarian fluid, Torvald found that guarding males have sperm that are designed to swim fast in ovarian fluid whereas the sneaker males sperm are designed to swim fast in water. Thus, sperm production in the two reproductive roles seems to be adaptively tailored to different external environments.