research
contact joris.koene-at-vu.nl for student projects, collaborations and funding options
(e.g. NWO, KNAW, AvH, JSPS, ERC)



The main interest of my research group revolves around reproduction in simultaneous hermaphrodites. Many of the questions we address focus on issues of sperm competition and sexual conflict and attempt to integrate different biological levels (e.g., behaviour, evolution, ecology, physiology, neuro-endocrinology). We make use of a range of different techniques, among which quantification of behaviour and resource investment, molecular phylogeny reconstruction, paternity analysis, biochemical and genetic identification and analysis of pheromones and allohormones, immunohistochemistry, micro-surgery, neuroanatomy and physiological experiments. For many of our experiments we use the model species (great pond snail Lymnaea stagnalis), but we also use these findings in comparative approaches within freshwater snails. In a second line of research we explore sexual conflicts caused by some of the most bizarre reproductive behaviours found in hermaphrodites, which often involve love darts and other strange sexual attributes. The latter includes the use of the model species Cornu aspersum (formerly Helix aspersa) as well as other land snails.
Our aim is to integrate our findings into a complete and general picture of why and how sexual selection - in this case including sperm competition and sexual conflict - affects simultaneous hermaphrodites. Such a broad synthesis is expected to significantly contribute to a full understanding of hermaphroditism as a reproductive strategy.


selected topics

Sperm and seminal fluid
We investigate both components of semen - sperm(atozoa) and seminal fluid - in hermaphrodites. For sperm, we are especially interested in how they compete for the fertilization of eggs and get stored and digested. For seminal fluid, we focus on those components that influence the recipient's physiology to enhance fertilization success of the sperm donor, possibly beyond the recipient's optimum.

Mating decisions and pheromones
Animals are often choosy about whom they mate with. We are investigating the involvement of factors such as body size, age, shell shape (chirality), mating history, mucus trails and pheromones. In addition, we aim to link this to how animals detect cues that are relevant for mate choice (including motivation and learning).

Love darts, penial glands and more
We investigate and compare love dart shape, function and use both within and between dart-possessing land snail species. Other odd sexual organs, such as elaborate penial glands in land slugs and dart-like stabbing devices in snails, are also addressed. Such projects include comparative physiology and the identification of the involved neuropeptides and allohormones.



the molluscarium

In our snail breeding facility, we breed the great pond snail Lymnaea stagnalis year round in large quantities in laminar flow tanks. We are also equipped with several breeding racks allowing us to maintain smaller populations of different genotypes or isolines. The latter set up is also used to maintain populations of several other species of freshwater snails (e.g., Biomphalaria glabrata, Physa acuta, Helisoma duryi, Planorbis planorbis, Stagnicola corvus, Radix balthica, and more). We also maintain, but currently do not breed, several species of land snails.