Research

One of the major questions in evolutionary biology is 'Why Sex?'. This 'queen of problems' puzzled biologists for decades. The question is, why are the huge majority of organisms mixing genomes through sexual reproduction involving males and females, when there is the straight-forward way of just producing asexual females. And it is not just a little bit of sex every now and then, but high rates of outcrossing. Sex has many costs. Demographic costs of males, transmission costs, costs of mating (predator exposure and STDs), ... and so on. But albeit these many-fold costs, sex must have some profound advantage compared to completely asexual female populations.

There are a lot of theories for the advantages of sex, and some were proven to work under lab conditions, but for natural populations, most of them remain elusive.

In the Bast-Lab, we are interested in the genomic consequences of asexual reproduction in such natural populations. We try to elucidate, if predicted consequences are found in nature.

Main focus of the lab’s research are those animals that likely existed longer than predicted extinction times. The so called 'ancient asexuals'. We try to shed light into the peculiarities of natural populations of ancient asexual animals compared to sexuals, to help explaining 'Why Sex?'.

Our model system to understand the “genomic substrate for persistence without sex” are oribatid mites (Acariformes, Oribatida). The tiny (< 1 mm) oribatid mites, are species-rich (> 10,000 species) and highly abundant (up to 350,000 ind./m²)⁠⁠. Several families are exclusively asexual. Asexuality has been a successful strategy for many oribatid mite species as many asexual lineages are species-rich and evolved and radiated over long periods of time. The most important benefit of this system is the presence of evolutionary replicates of different phylogenetic relatedness and age, making sex-asex comparative investigations possible.

We want to know what is going on with the mites. Why are they so special? What can we learn from them about the existence of sex?
How old are asexual oribatid mites really? How does speciation work in these asexuals (nobody knows because these mites are one of the very few cases where speciation without sex was documented)? What roles do standing genetic variation and population sizes play in the escape of extinction?