And now, an entry about why I photographed this small brown fly.
Students of introductory biology will recognize Drosophila melanogaster (see photo below) as the famous laboratory fruit fly whose mutations taught early geneticists about genes and chromosomes. But this post isn't about Drosophila melanogaster. After all, that species is not the only fruit fly. In fact- digression!- Drosophila isn't even a true fruit fly. That title is officially reserved for another family entirely, Tephritidae, while the thousands of species of Drosophilidae are technically vinegar flies.
No, this post is about another species, the dark one in the top photograph.
In the early 20th century, Drosophila melanogaster had performed admirably for basic studies of inheritance. But it wasn't suited to all questions. By the 1930's, the new evolutionary synthesis had sprouted wings and biologists like California's Theodosius Dobzhansky were looking beyond simple inheritance to the behavior of genes in the real world. Lab flies wouldn't do; they needed natural populations. Drosophila melanogaster was too closely associated with human commerce to reliably reveal patterns of evolution in the field.
So biologists searched for a wild fly. What they found, all up and down the west coast of North America, was a common, dark-colored relative, Drosophila pseudoobscura. When wild populations of this species showed signs of genetic differences from place to place, the fate of D. pseudoobscura as an evolutionary guinea pig was sealed. If Drosophila melanogaster was the iconic laboratory genetics animal, Drosophila pseudoobscura became the iconic field genetics animal. While D. melanogaster taught us about genes and inheritance, D. pseudoobscura taught us about the evolution of new species.
As a measure of this animal's importance, Google Scholar now lists more than 12,000 academic articles for "Drosophila pseudoobscura". You'd think this would be a well-photographed species. But you'd be wrong. Imagine my surprise when an image search for this animal turned up a paltry sample of photographs, many of the wrong species:
Among the few illustrations of real D. pseudoobscura are D. persimilis and D. melanogaster mislabelled as D. pseudoobscura and a calyptrate muscoid in a completely different fly family. Most other photos were small, blurry, or showed dead flies rather than living ones.
Why so few decent photographs of such an evolutionary icon? This was a job for a bug photographer!
I got my hands on live D. pseudoobscura lab stock, and these photos are the result.
I hope you enjoy these new images, and I hope they bring some small recognition to the existence of more than just one fruit fly.
- Lewontin, R.C, Hubby, J.L. 1966. A Molecular Approach to the Study of Genic Heterozygosity in Natural Populations. II. Amount of Variation and Degree of Heterozygosity in Natural Populations of DROSOPHILA PSEUDOOBSCURA Genetics. August; 54(2)595.
- Starting "The Modern Synthesis": Theodosius Dobzhansky.