Drosophila subobscura Raw sequence reads. Drosophila subobscura

Understanding the forces that maintain diversity across a range of scales. Frequency-dependent processes are recognized as the central process for the maintenance of ecological diversity. The same is, however, not generally true for genetic diversity. Negative frequency dependent selection, where rare genotypes have an advantage, is often regarded as a relatively weak force in maintaining genetic variation in life history traits because recombination disassociates alleles across many genes.We studied what is essentially a ubiquitous life history supergene (i.e., mitochondrial DNA) in the fruit fly Drosophila subobscura, showing sympatric polymorphism with two main mtDNA genotypes co-occurring in populations world-wide.Using an experimental evolution approach involving manipulations of genotype starting frequencies, we show that negative frequency dependent selection indeed acts to maintain genetic variation in this region. Moreover, the strength of selection was affected by food resource conditions.