Abstract

When conspecific or closely related populations are crossed, the ensuing hybridisation can result in unique hybrid phenotypes, extreme in relation to that of the parents. A possible hybrid effect is transgressive segregation, where heritable quantifiable hybrid traits, either phenotypic or genotypic, are non-additive or differ significantly from the mid-parental value. Recent studies have found trangressive segregation of small RNA expression in higher plants. In this PhD, the unicellular green algae Chlamydomonas reinhardtii will be used to investigate the transgressive segregation of small RNA populations and other possible hybrid effects on small RNAs. Crosses will be set up between genetically divergent yet conspecific strains to allow comparison between the parental and hybrid genomes. To investigate the mechanism of transgressive segregation, RNA silencing mutants and studies of the epigenome will be used. Characterizing hybridisation in C.reinhardtii could provide insight into the function of small RNAs in unicellular algae and the role of small RNAs in speciation in general.