Our research involves a variety of model and non-model organisms ranging from bacteria to whales, but most of the experimental work in the lab capitalizes on two model systems, Xenopus and Drosophila.
Despite decades of research on ribosomal RNA, little is known about how rRNA genes are selected for inactivation at the genome-wide level. We have recently discovered that rDNA in Xenopus hybrids is expressed predominantly from maternal copies, thus proving that parental genome imprinting can be well established in organisms without intimate parent-offspring interactions during the embryo development. This is not only the first evidence for genome imprinting in amphibians, but also a new example of a dramatic epigenetic phenomenon comparable only with X chromosome inactivation in mammals.
If diversity is essential to population survival, it would be highly adaptive for organisms to increase genetic variation in challenging (stressful) environments and decrease it under optimal conditions. Such variation of recombination should increase the population adaptability without excessive dissipation of the accumulated hidden genetic variation in favorable times. We conduct rigorous tests for recombination plasticity at the genome-wide level, including its dependence on stressful conditions and modulation by individual’s stress tolerance, using Drosophila melanogaster as an experimental model. Preliminary results demonstrate paucity of standing variation for fitness-related traits, giving individuals with a higher recombination rate an advantage to generate more diverse progeny with higher response to selection. In addition to evolutionary experiments in the lab, we have also investigated recombination rates and fitness along microclimatically heterogeneous gradients in natural settings, namely “Evolution Canyon” (Lower Nahal Oren, Mt. Carmel, Israel).