Phylogenetic study of cephalopharyngeal sclerites and mouth hooks dentition in different species of drosophila larvae

Abstract EN

Drosophila larvae of different species were subjected to this investigation in order to study the structure of cephalopbaryngeal armature and mouth hooks dentition in correlation with their food resources (food habitat) which are more likely genetically controlled* A comparative study of third instar larvae was carried out using a large stock of mass bred population cage which established from fourteen isofcmaJe inbred lines of Drosophila melanogaster Scraleone strain, and eight species of Drosophila melanogaster species subgroup, sincc these species were breeding in laboratory for several generations feeding on yeasted oatomeal medium under room conditions at about 25 ± 1 C°, in addition to the five fungal breeding wild type species.

The statistical analysis of the results revealed: 1- there was high significant differences in teeth number among the three larval stages of D.

melanogaster specics which evolutionary reflects the natural development related with the food acquisition for each larval stage.

2- There was a highly significant heterogeneity of variance between the lines, the interesting here was that the average among the lines variance is substantially greater than the sample variance for the mass bred population.

3- Non-parametric test indicated that the differences between the eight species of D.

melanogaster spccies subgroup were highly significant, since these species differ in their geographical distribution.

4- Ihc ccphalopharyngeal seclerites and the mouth hooks of the five fungal breeding species were more robust and the dentition was larger , so the difference between the five means were significantly high , which may be due to their food resources difference.

5- Inbreeding effects on the stability of mouth tooth number were investigated by comparing the expressing of character in the large cage population and 15 isofemale inbreed strains.

Introduction