Fly-worm-yeast
	30% of fly genes have orthologs in worm; 20% in both worm and yeast; 50% of fly proteins have some similarity to mammalian proteins more multidomain proteins in fly, worm 10-30% of genes in most organisms seem to be unique only C elegans and closer organisms will have homologs for the majority of disease genes (80- 90% in mouse); analysis of domain structure may still be helpful