Research Projects
Recombination landscape in birds
Meiotic recombination is a fundamental cellular process in all sexually reproducing organisms to ensure proper segregation of homologous chromosomes in meiosis. In the context of population genetics, recombination contributes to patterns of genetic diversity by shuffling alleles between chromosomes. At the same time, restriction of recombination can facilitate species divergence by maintaining specific allelic combinations important for reproductive isolation and local adaptation.
In recent years, we are learning that location and frequency of recombination is very different between species and even between individuals of the same species. However, we know very little about what causes such variation and how such variation affects patterns of genetic diversity and species divergence. We are addressing these quenstions by using whole genome re-sequencing of old world flycatchers (genus Ficedula).
Collaborator: Hans Ellegren (Uppsala University)
Chromosomal speciation
Structuctural changes in chromosomes can drastically change patterns of recombination in genomes of two diverging populations. Recent theoretical developments have suggested that those rearranged regions may promote speciation and adaptation in the face of gene flow by suppressing recombination and extending the effects of linked reproductive isolation genes or locally adapted alleles (referred to as the 'suppressed-recombination models'). We are testing these theoretical predictions by comparing the level of gene flow between rearranged and non-rearranged chromosomes across hybrid zones of
chromosomally diverse grasshoppers in Australia (Vandiemenella viatica)
Collaborator: Simon Baxter (University of Adelaide)
Steve Cooper (University of Adelaide)
Roger Butlin (University of Sheffield)
Sex chromosome evolution
Chromosomal rearrangements can play partcularly important roles in speciation and adaptation when a fusion between sex chromosomes and autosomes results in the formation of neo-XX/XY sex chromosome systems. It has been considered that recombination is maintained between neo-Y and homologous region of X chromosomes at the onset of chromosome fusion; however, genomic sequences as well as gene expression profiles gradually diverge in these regions when recombination between the two chromosomes ceases by accumulating repetitive sequences. Vandiemenella viatica species group, comprising 12 chromosomal races with 3 independent evolution of neo-XY sex chromosomes, offers a unique model system for studying temporal mode of gene degeneration and gene expression divergence in response to loss of recombination and population size decrease.
Collaborator: Simon Baxter (University of Adelaide)
Steve Cooper (University of Adelaide)
Roger Butlin (University of Sheffield)
Transposon proliferation by exposure to environmental stress
Transposable elements are often referred to as 'genomic parasites' and are capable of moving around and making their own copies in a genome. Because uncontrolled proliferation of transposable elements can signicantly reduce fitness of host organisms by destroying genes or modifying patterns of gene expression, activity of transposable elements are genetically and epigenetically repressed by host genomes. However, under special conditions, transposable elements can escape from such genetic control and proliferate in their host genomes. We are investigating whether exposure to various biotic and abiotic stresses, such as heavy metal, pesticides, and paracites, can induce mobilization of transposable elements in several grass and insect species.
