I am interested in the evolution of transposable elements (TEs), such as short interspersed elements (SINEs) and long interspersed elements (LINEs). These retroposons, that propagate within the host genome via RNA intermediates, represent highly repetitive components of all eukaryotic genomes and often account for up to 50% of the total DNA sequence. Repetitive elements can substantially alter the DNA of their host genomes and carry the potential to greatly enhance genetic diversity. Because TEs integrate randomly into genomic DNA, the integration of a SINE or other TE at a specific genomic location represents a strict synapomorphy for all taxa that share that orthologous trait. Therefore, presence/absence analyses of these elements is a robust molecular approach for phylogenetic studies. Furthermore, although TEs preferably integrate into non-functional regions of the genome, it has recently become evident that SINEs can affect gene function by acting as enhancers of important developmental genes. SINEs, LINEs and other TEs are therefore important 'evolution accelerators' of their respective host genomes. Detailed characterisation of TEs using both experimental and computational approaches will be indispensable for understanding the ways in which metazoan genomes have evolved.