The researchers have been tracking the evolution of Drosophila subobscura, a small fly that is very common all over Europe, since 1976. They are focusing on a specific type of genomic variability known as chromosomal inversion polymorphism. The study has compared how the flies' genomes change from spring to summer, summer to autumn and autumn to spring, over the years.
In pre-2011 studies of one of D. subobscura's five chromosome pairs, performed in a population near the town of Santiago de Compostela, the researchers observed that this type of adaptation is related to changes in environmental temperature. Two types of genetic variation were identified: one that adapts to the cold, since its frequency always increases in winter, and another that adapts to heat, showing the opposite behaviour pattern. The relative frequency of both types of variation was seen to have evolved in consonance with climate changes. Present-day flies present more heat-tolerant varieties than those of the 70s.
In April, 2011, monitoring coincided with the intense heatwave that struck western Europe and other parts of the world. The study was widened to cover not only the original chromosome pair but all the species' five chromosome pairs, and fly samples were collected from another population, in Gordexola, near Bilbao. The conclusions could therefore be extrapolated on a genome-wide scale and on a geographical scale, to the northern third of Spain.
In an article in the prestigious journal Biology Letters, of the British Royal Society, the researchers show that the 2011 heatwave dramatically altered the genetic constitution of natural populations of Drosophila subobscura. In the middle of spring, and over a single generation, the populations acquired a genetic constitution typical of the summer, because of the heatwave.
According to the study's findings, the difference in reproductive success between genotypes that were
|Contact: Octavi López Coronado|
Universitat Autonoma de Barcelona