At the moment we have the following projects in our lab:
  • Evolution of the number of copies of MHC genes: testing optimality hypothesis and exploring alternatives.
MAESTRO grant to JR funded by Polish Science Centre (NCN).

Genes of the major histocompatibility complex (MHC), coding for proteins involved in parasite recognition in vertebrates, but also playing a role in mate choice and social interactions, are a paradigm for the maintenance of adaptive polymorphism. However, our understanding of the evolution of the number of expressed MHC molecules is only rudimentary.

The first aim of the project is to test the crucial prediction of the optimality hypothesis (Nowak et al. 1992), which poses that increased parasite recognition capacity associated with expressing many MHC molecules is counterbalanced by the simultaneous decline in T-cell repertoire. This prediction will be tested in the bank vole Clethrionomys glareolus a species showing extensive inter-individual variation in the number of classical MHC genes expressed.

The second aim of the project is to explore, by means of computer simulations, alternative mechanisms potentially shaping the number of expressed MHC genes, including mate choice and constraints on the evolution of proteins expressed by pathogens.
  • Testing new MHC allele advantage in semi-natural populations of the guppy, Poecillia reticulata.
Collaborative grant lead by JR with dr Cock van Oosterhout (University of East Anglia) and dr Joanne Cable (Cardiff University, School of Biosciences) funded by Polish Science Centre (NCN).

Genes of the Major Histocompatibility Complex (MHC), involved in parasite recognition, are crucial for adaptive immune response in vertebrates. The extreme polymorphism of these genes continues to be a major focus of evolutionary biology. While theories explaining maintenance of MHC polymorphism have been proposed decades ago, empirical tests of some of the most influential hypotheses are scant. Most notably, predictions about frequency-dependence selection (i.e. the hypothesis that rare and novel MHC alleles should be selected for because fast-evolving parasites will adapt to evade immune recognition by common MHC alleles) have not been tested.  The aim of this project is to test two crucial predictions of this hypothesis using semi-natural populations of the guppy, Poecilia reticulata:

  • Individuals possessing new MHC alleles will be burdened with fewer parasites than individuals without such novel MHC alleles.
  • The frequencies of the newly introduced MHC alleles will increase relative to the frequencies of newly introduced neutral marker alleles over generations.
  • Genetic basis and adaptive significance of male dimorphism in two species of acarid mites with contrasting morph determination systems.
Funded by Polish Science Centre (NCN) to JR, hosted by Jagiellonian Univeristy, Kraków.

Alternative mating tactics are among most spectacular examples of discontinuous phenotypic variation within species. Acarid mites, where a number of species is characterised by the presence of discontinues morphologies (armed vs. unarmed) associated with alternative bahavioural tactics (fighting vs. scramble competition) determined either genetically or by environmental cues, provide an excellent system to study evolution of alternative phenotypes and evolutionary transitions between canalised and plastic phenotype determination.

The study will use two congeneric acarid species, Rhizoglyphus robini and R. echinopus, differing in male determination mode (genetic and environmental, respectively) to identify genes involved in male morph expression, and to identify common and mode-specific expression patterns.