The Development of Larval Behaviours in Sympatric Chilean Populations of Drosophila Melanogaster and Drosophila Simulans

AbstractThe patterns of movement and foraging were investigated in larvae of the Chilean sympatric species D. melanogaster and D. simulans. Frequencies of 'rover', 'sitter' and 'digger' larvae, as well as locomotion and the angle size of turning were recorded in nutritive and non-nutritive environments. In these environments the sibling species differ in frequencies of 'rover', 'sitter' and 'digger' larval phenotypes. There are also differences in these frequencies between the populations of each species and across larval age. As development proceeds, the larvae of D. melanogaster and D. simulans become more diverse in their behaviours. Depending on larval age, strain and species, larval locomotion may be: i) similar in the presence and in the absence of food (D. simulans), ii) lower in yeast suspension than on agar (D. melanogaster), iii) higher in the presence of food than on agar (D. simulans). The angle size of larval turning also shows variability which depends on larval age, strain and species. Statistical significance of the correlation between locomotion and turning, and the regression of turning on locomotion in larvae of D. melanogaster and D. simulans depends on larval age, strain, species and the environment in which the larvae grow.