Hello,
I am doing biodeversity survey and experience difficulties in Drosophila identification via morphological analyses. All the identification keys, for Drosophila, that I took a look on says that D. simulans could be distinguished from D. melanogaster by a genetal arch. However, females have no genetal arch. So, do anybody aware about morphological traits for females, according to which I can descriminate between D. simulans and D. melanogaster.
Thank you.
Wing color, lower abdominal segments are differently colored, body size of D. simulans on an average remains larger than D melanogaster. Counting of hairs in mouth apparatus mainly laginea will be quite different.
I am not sure, but according to wikipedia, there may be some body color related differences between females of these two species.
Wing color, lower abdominal segments are differently colored, body size of D. simulans on an average remains larger than D melanogaster. Counting of hairs in mouth apparatus mainly laginea will be quite different.
According to: Markow and Grady. 2005. Drosophila: A Guide to Species Identification and Use. Academic Press: London. Specifically, Chapter 6 "Handling wild-caught specimens" (page 182): "For many related species, such as D. melanogaster and D. simulans, or D. pseudoobscura and D. persimilis, females are indistinguishable even with a microscope, so that simply pooling flies which look alike could produce mixed-species cultures."
Another key by Heed, "Field key to the common species of Drosophila in Southern Arizona" suggests that females can be distinguished by body shape and eye distance with approximately 80% accuracy (couplet 13).
I suggest molecular identification or by allowing the wild caught females to oviposit and identifying the female based on the morphology of her male offspring.
http://www.academia.edu/1538134/Drosophila_A_Guide_to_Species_Identification_and_Use
http://comp.uark.edu/~wetges/Heedkey2.pdf
I agree with Meaghan. I've noticed that the pigmentation differences (the sixth tergite in melanogaster females is pigmented to the ventral margin, but on simulans females there is less pigmentationm and it doesn't go to the margin) are pretty consistent, but the only way to know is by molecular ID or looking at a female's sons. In your survey, I'd use males to estimate the percentage of simulans vs. melanogasgter in a population.
Markow and Grady are too pessimistic ! It's not impossible by any means. Simulans females can be separated from melanogaster females fairly accurately (95% accurately and more with a bit of practice) by looking at the abdominal pigment pattern and eye size relative to head (see for example http://gent.uab.cat/msantos/sites/gent.uab.cat.msantos/files/EntomNews_1998.pdf).
Much simpler though is to check their eggs. Mel eggs have 2 angled filaments the last third of which are flattened with an oblique end. Simulans eggs have 2 unangled filaments, not flattened at the ends, and tapering to a point. You can check these differences because females often release an egg under CO2 narcosis, or by letting females lay individually (2mL eppendorfs are convenient), or if they're dead, pull out the oviduct quickly and look at the mature eggs inside.
- Badges
- Science topic
- Similar topics
- Biological Science
- Zoology
- Invertebrate Zoology
- Entomology