Genetic conflict and sex allocation in scale insects

PhD ceremony: Ms. L. Ross, 13.15 uur, Academiegebouw, Broerstraat 5, Groningen

Thesis: Genetic conflict and sex allocation in scale insects

Promotor(s): prof. I. Pen, prof. L. Beukeboom, prof. F. Weissing

Faculty: Mathematics and Natural Sciences

Laura Ross has explored the hypothesis of the ‘selfish genes’ focussing on one particular group of organisms: the scale insects, which are characterized by their incredible variation in weird reproduction and genetics.

There is extensive variability in the way individuals of different species reproduce and how their genes are inherited from generation to generation. However why these processes - so fundamental for life - are so variable is poorly understood. A recent hypothesis suggests that reproductive processes might be variable because they are affected by the evolution of “selfish” genes that try to increase their own frequency in the next generation by hijacking the reproductive machinery. These genes are often harmful for the individual they are in and therefore other genes are selected to suppress the selfish ones. This results in what is called genetic conflict.

Ross has explored this hypothesis. Using a variety of different approaches, she suggests that some of the unusual ways in which scale insects reproduce might have indeed evolved as a result of conflict. These include asexual reproduction, hermaphroditism - where an individual can produce both sperm and eggs - and various systems where males develop from fertilized eggs but lose their father’s genes during development. Ross also shows that different types of conflict may interact in scale insects, including conflict between genes within an individual that come from either the mother or the father, but also conflict between genes of the scale insect and those of the bacteria that live within these insects.