We study the enormous diversity of nematodes in the face of climate change and want to learn how some species can survive without sex for millions of years.
Roundworms own this earth
"In short, if all the matter in the universe except the nematodes were swept away, our world would still be dimly recognisable, and if, as disembodied spirits, we could then investigate it, we should find its mountains, hills, vales, rivers, lakes, and oceans represented by a film of nematodes. The location of towns would be decipherable, since for every massing of human beings there would be a corresponding massing of certain nematodes. Trees would still stand in ghostly rows representing our streets and highways. The location of the various plants and animals would still be decipherable, and, had we sufficient knowledge, in many cases even their species could be determined by an examination of their erstwhile nematode parasites." Nematodes and Their Relationships, Nathan Cobb, 1915
Biodiversity of Nematodes
As Nathan Cobb said in 1915, roundworms are everywhere on earth. They can be found in the deep seas, in deserts, in every compost heap, and, as parasites, in plants and animals (including humans - see NTDs). We are particularly interested to learn more about nematodes in extreme habitats where there is only occasional availability of water. There are roundworm species, which can completely dry (desiccate) and come back to life once water is available again. In simple terms we want to learn how many of these species there are, how they survive desiccated for many years, and in particular how they maintain stability of their DNA.
Parthenogenesis in Nematodes
Sex as a mode of reproduction, is quite costly as, for example, you have to allocate resources to producing males, to find a partner, and for the act itself. Still, almost all animals reproduce by having some sort of sex, that is they recombine their genetic material and then mix it with a mate. Thus, the cost to pay for sex must be out-weighted by its benefits. In fact, it is assumed that most species, that switch to an asexual (parthenogenetic) mode of reproduction, go extinct in short evolutionary time.
So why then are there so many nematode species, which are parthenogenetic? And how do they become parthenogenetic and maintain this mode of reproduction of prolonged evolutionary times? We try to answer these question in the context of nematode diversity and ecology, and also from a molecular evolutionary perspective.