One of the most researched genomes in the world is that of the Drosophila fruit fly. This species is also known as the common fruit fly or vinegar fly. There are a number of reasons this is so useful including the ease in raising them and their short lifespan. This makes them one of the perfect genomes to use in comparative genomics because both the similarities and differences tell us more about who we are as a species.
The first thing of importance is that the genome of the drosophila fruit fly is small compared to humans both in similarities and differences. It has four chromosome pairs in comparison to humans, which have 23. They also have far fewer base pairs than humans, which have about 3 billion. It appears that a far higher percentage of their genome is functional than that of humans, with over 60 percent of it being non protein coding DNA.
In order to understand the differences it is useful to know some of the similarities. All genomes on earth are similar in the way that data is stored in them and how they react to changes. In addition even the most diverse of creatures have similar sections of genome which do similar things. For example, nearly 75 percent of human genetic disease genes have a match in the fruit fly. This allows for testing of these diseases that would otherwise be very hard and slow work.
Perhaps the most interesting difference between the two genomes, as well as the most useful, is that the nucleotide diversity is ten times larger in the fruit fly genome. This means that if you look at any two nucleotides, the odds of them being different in a fruit fly is ten times higher. This differences allows for biologists to see a lot of variation in how genes can be represented, but it does something else very valuable, as well. It helps to show us just how closely related all humans are to each other. This is one of the things that helped to lead scientists to the understanding of mitochondrial Eve, a single human from whom all humans appear to have descended. It also shows a possibility of the variations of human genome because they have simply had far more generations than humans.
The process of comparative genomics is one that was almost impossible a few years ago, and the speed at which we are understanding humans and the process of life in general is improved greatly by this process. One of the most useful of these comparisons is the genome of the Drosophila fruit fly, because it has been examined more than any animal on earth, with the possible exception of humans, and the differences between them and humans are some of the most important studies in modern biology.
http://eebweb.arizona.edu/Courses/Ecol426_526/Aquadro_et_al_2001.pdf
http://www.genome.gov/11509542
