Species barriers commonly manifest themselves as reduced hybrid viability and/or fertility. When it is feasible to obtain viable and flowering hybrids between species, their fertility is commonly compromised. Often fertility reduction is due to chromosomal differences between parental species that cause meiotic problems during gamete development in hybrids. But for recently diverged species pairs that share the same chromosome number and the genomes are largely collinear, the underlying mechanism is thought to involve epistatic interactions, incompatibilities, between genes. In my research I am investigating underlying genetics for reproductive isolation in hybrids within and between outcrossing Arabidopsis species (A. lyrata, A. halleri and A. arenosa). I am especially interested in reduction of hybrid pollen fertility as it is one of the first barriers to emerge between incipient species. In addition, I am interested in evolution of cytoplasmic male sterility (CMS) and genetics of morphological traits that may contribute to local adaptation and whether there is any correlation between ecological divergence and reproductive isolation. In my on-going work, I also wish to explore genetics of clonal growth and how does it affect survival and sexual reproduction.