A latitudinal cline in a Drosophila clock gene

Area of Science:

• Genetics and Evolutionary Biology
• Chronobiology
• Population Genetics

Background:

• The 'period' clock gene in Drosophila melanogaster is crucial for biological rhythmicity.
• This gene encodes a protein with a unique threonine-glycine repeat region.
• The length of this threonine-glycine repeat region exhibits polymorphism in natural fly populations.

Purpose of the Study:

• To conduct a geographical analysis of the length polymorphism in the threonine-glycine repeat region.
• To investigate the distribution of this genetic variation across Europe and North Africa.
• To explore potential selective pressures, such as thermal selection, maintaining this polymorphism.

Main Methods:

• Geographical sampling of Drosophila melanogaster populations across Europe and North Africa.
• Analysis of the length polymorphism within the minisatellite region encoding the threonine-glycine repeat.
• Statistical analysis to identify geographical patterns and correlations.

Main Results:

• A distinct clinal pattern in the length polymorphism was observed along a north-south axis.
• Geographical distribution of the polymorphism suggests regional adaptation.
• The observed pattern is consistent with geographical temperature gradients.

Conclusions:

• The length polymorphism of the threonine-glycine repeat in the period gene shows a significant geographical structure.
• Thermal selection is a plausible mechanism maintaining this polymorphism, potentially linked to thermostability.
• This study highlights the role of environmental factors in shaping genetic variation in clock genes.