The forgotten Drosophila: suzukii and yakuba

The fruit fly Drosophila melanogaster is one of the most commonly used model organisms worldwide, but it’s just one of over 1,600 different species of fly in the Drosophila genus.1 Two other species, Drosophila suzukii and Drosophila yakuba, have also been widely studied, albeit not nearly as much as D. melanogaster. In this post I’ll explain the evolutionary relationship between the various species of the Drosophila genus, and also note some morphological differences among these interesting flies.

Drosophila suzukii: Invasive pest species

Drosophila suzukii, also known as Spotted Wing Drosophila (see image below), is a well known crop pest species endemic to Asia, including China, Japan, and Korea. Since 2008, when it was first identified in California, it has spread throughout North America (likely jumping from Hawaii) and Europe. D. suzukii is so destructive because it deposits its eggs in thin-skinned, healthy whole fruit, such as grapes and cherries, rather than rotting fruit as D. melanogaster does.

Drosophila suzukii
Drosophila suzukii female (left) and male (right). Image source: Russell IPM, Integrated Pest Management.

Because Drosophila suzukii deposits its eggs in whole fruit, it needs a sharp ovipositor to penetrate the fruit’s skin. You can see the clear differences in Drosophila ovipositor shape in the images below (on the right is a close-up view of D. suzukii’s serrated ovipositor).

Drosophila yakuba: African fruit fly

Drosophila yakuba is fairly similar in appearance to D. melanogaster, with the characteristic females’ yellow abdomens striped with black, while those of males have black tips (see image below).
D. yakuba is distributed throughout sub-Saharan Africa, sticking mainly to open forest and savanna.2

Drosophila yakuba
Drosophila yakuba male (left) and female (right). Image source: CRISPR Fly Design

Evolution of the Drosophila genus

Based on genome analyses, our current understanding of how the Drosophila genus evolved suggests that D. melanogaster and D. yakuba are more closely related to each other than either of those species is to D. suzukii — in other words, they share a common ancestor more recently. This is not surprising, considering Drosophila suzukii‘s strikingly different morphology. In the phylogenetic tree below, you can see that all three species — melanogaster, yakuba, and suzukii — belong to the Sophophora subgenus of the Drosophila genus (of the Drosophildae family).3

Drosophila phylogenetic tree
Image source: Nature Communications.

Although D. melanogaster continues to reign supreme as the preferred Drosophila model system, there is great value in studying many species within the same genus and sequencing their complete genomes.4 These investigations allow us to infer evolutionary relationships among species, determine how certain morphological features are correlated with genetic variation, and better understand how species have become geographically distributed over time.

If you enjoyed this overview of some forgotten Drosophila species, check out my post on the genetics of Drosophila melanogaster body color.


References

  1. Patrick M O’Grady, Rob DeSalle, Phylogeny of the Genus Drosophila, Genetics, Volume 209, Issue 1, 1 May 2018, Pages 1–25, https://doi.org/10.1534/genetics.117.300583
  2. Ana Llopart, Daniel Lachaise, Jerry A Coyne, Multilocus Analysis of Introgression Between Two Sympatric Sister Species of Drosophila: Drosophila yakuba and D. santomea, Genetics, Volume 171, Issue 1, 1 September 2005, Pages 197–210, https://doi.org/10.1534/genetics.104.033597
  3. Keesey, I.W., Grabe, V., Gruber, L. et al. Inverse resource allocation between vision and olfaction across the genus Drosophila. Nat Commun 10, 1162 (2019). https://doi.org/10.1038/s41467-019-09087-z
  4. Drosophila 12 Genomes Consortium. Evolution of genes and genomes on the Drosophila phylogeny. Nature 450, 203–218 (2007). https://doi.org/10.1038/nature06341

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