One important, and to a great extent unaswered question in evolutionary biology is Why is there so much sex. Theoretically, asexual populations, where all the reproductive energy goes into eggs, should outcompete sexual populations, where at least some of the energy has to be invested into sperm (and therefore males). The fact that sexual reproduction is so widespread implies that there must be some advantages to it over asexuality. By understanding the factors affecting the investment of resources into sexual reproduction, one can expect to shed some light on this question.
Simultaneous hermaphrodites, where each individual can allocate to both male and female reproduction, are a fantastic system to study such factors. First, the sex-allocation ratio (how much goes into one or the other function) can be measured within one single organism, thus controlling for genetic and developmental variation. Second, the fact that a male is always attached to a female strengthens the sexual conflicts and thus their effect on sex allocation.
Macrostomum, a small marine flatworm, is a simultaneous hermaphrodite, with a relatively short generation time, and a very convenient transparency: one can see and measure different internal structures non-invasively! In working with Macrostomum one gets interested in many different things. Below is a subset into which I tried to peep, in the lab of Lukas Schärer.
I have looked at aspects of the ecology of sex allocation, trying to find out what may influence sex allocation in nature. Besides the previously known effects of group size (Schärer & al) we have added resource availability to the list. [more]
I am also interested in the evolution of sexual conflicts, and how these can develop into sexual conflicts between male and female functions. [more]
In working with Macrsotomum, one is often faced with open questions about its basic ecology. How diverse is its natural diet? Under which conditions, how, and how long does it encyst? cetera, & cetera... [more]
Finally (at least by now), I am also interested in Macrostomum phylogeny, from a molecular as well as a morphological point of view. [more]
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last uptaded: 27.10.2007