Research

Currently we attempt to solve the following problems:

1. Phylogenetic interrelationships among free-living, predatory litostomatean ciliates
2. Diversity and evolution of hindgut ciliates from wood-feeding cockroaches and their associations with prokaryotes
3. Evolution of the ciliate/invertebrate symbiotic systems
4. Diversity and evolution of freshwater gastrotrichs

1. Phylogenetic interrelationships among free-living litostomatean ciliates

The class Litostomatea represents a monophyletic group, comprising both predatory and endosymbiotic ciliates distributed all over the globe. At first glance, litostomateans are rather simple, uniformly ciliated protists having bursiform bodies. Their oral structures are very diverse, a fact that was used in their morphology-based taxonomy during the ultrastructure era. In the recent decades, the systematic research on litostomateans has concentrated mainly on the ribosomal RNA genes and ITS-region sequences. Phylogenetic relationships among main free-living litostomatean lineages are still unresolved, however. We search for evolutionary forces and investigate problems that might be associated with the puzzling picture in litostomatean phylogenies. We also examine the utility and phylogenetic information content of ribosomal and protein-coding genes in free-living litostomateans.

2. Diversity and evolution of hindgut ciliates from wood-feeding cockroaches and their associations with prokaryotes

The ability to digest wood evolved two times independently in the insect order Blattodea. First, in the common ancestor of termites and cryptocercids, and then in the panesthiine cockroaches. The hindgut compartment of panesthiines harbors a diverse, anaerobic microbial community, including also three closely related ciliate genera Clevelandella, Paraclevelandia, and Nyctotherus. These ciliates are, however, not associated with the digestion of wood but contribute to the overall hindgut function by their grazing behavior, which helps to shape and regulate prokaryotic populations. We investigate co-occurrence and correlation patterns of prokaryotes associated with these hindgut ciliates. We also study speciation, species borders, and mechanisms that have led to diversification of the hindgut ciliates.

3. Evolution of the ciliate/invertebrate symbiotic systems

Many animals, including planarians, annelids, mollusks, and crustaceans, have established associations with some epi- and/or endozoic ciliates. The diversity of these symbiotic systems is, however, far from being thoroughly examined. Our main goal is to address the following questions:

• How many times have ciliates entered into associations with invertebrates?
• How structurally and phylogenetically similar are communities of symbiotic ciliates?
• Does the position of symbiotic ciliates in phylogenetic trees follow the occurrence of their hosts in the geological history of Earth?

4. Diversity and evolution of freshwater gastrotrichs

Phylum Gastrotricha unites vermiform to bottle-shaped meiobenthic metazoans having locomotory ciliation on the ventral body surface and adhesive tubes distributed along the body or situated at the rear body end. The research on gastrotrichs is just at the beginning in Slovakia. The diversity of gastrotrichs is regrettably unexplored in this zoogeographically interesting region. There are globally approximately 890 validly described gastrotrich species, classified in two orders: the Macrodasyida with over 390 species and the Chaetonotida with almost 500 species. About two-thirds of chaetonotids are known from continental freshwaters. The gastrotrich diversity is, however, still insufficiently explored and the described species might represent less than 20% of the total richness.

Our main goal is to:

• Characterize and describe the gastrotrich diversity in various freshwater bodies in Slovakia, using an integrative taxonomic approach
• Determine phylogenetic position of detected species and unravel their evolutionary history
• Reconstruct morphological evolution and life histories of gastrotrichs