פרופ' לילך הדני

Population Genetics, Evolutionary Theory

My main research interest is variation in nature, and in particular the evolution of the mechanisms that generate variation: recombination, sexual reproduction, mutation, migration, outcrossing, alternative splicing, polyandry, and even early death. Using analytical models, computer simulations, and sometimes experiments we try to understand the forces driving variation, the patterns of variation expected in natural poplulations, and the evolutionary consequences of these patterns.

Major research projects:

1) The plasticity of variation. Assuming that an organism has some indication of its well-being in a given environment, we predict that the generation of variation (e.g., recombination rate) would evolve to be associated with that information: with the state of the organism, its sex, its age, and with environmental cues. In particular, we expect the generation of variation to increase with indications of low fitness, such as stress. We investigate the expected patterns and their implications to host-parasite interactions, stressful environments, and stress-related diseases.

2) The evolution of genome structure. How do recombination, mutation, and splicing evolve and co-evolve? When is sexual reproduction advantageous in comparison with asexuality? What are the implications to the distribution of recombination hotspots, mutation hotspots, and introns?

3) The evolution of complex traits. An open question in evolutionary biology is how a species can evolve from one co-adapted gene complex to a better one, crossing an adaptive 'valley' of less fit genotypes. We study how such adaptive peak-shifts are affected by genetic mixing and by heterogeneity of the environment.

4) Variation and selection within the organism. Most organisms are subject to evolution at more than one level: conflicts of interest can occur between branches of a tree, between different lineages within the germ line, and within the cells in the germ line themselves. A single eukaryotic cell is a community, including organelles, such as mitochondria and chloroplast, transposable elements, and the 'host' DNA. We study the interactions between these different evolutionary levels, and their implications to the higher levels: the entire organism and the population.