Data from: Genetic redundancy fuels polygenic adaptation in Drosophila

The genetic architecture of adaptive traits is of key importance to
predict evolutionary responses. Most adaptive traits are polygenic—i.e.,
result from selection on a large number of genetic loci—but most
molecularly characterized traits have a simple genetic basis. This
discrepancy is best explained by the difficulty in detecting small allele
frequency changes (AFCs) across many contributing loci. To resolve this,
we use laboratory natural selection to detect signatures for selective
sweeps and polygenic adaptation. We exposed 10 replicates of a Drosophila
simulans population to a new temperature regime and uncovered a polygenic
architecture of an adaptive trait with high genetic redundancy among
beneficial alleles. We observed convergent responses for several
phenotypes—e.g., fitness, metabolic rate, and fat content—and a strong
polygenic response (99 selected alleles; mean s = 0.059). However, each of
these selected alleles increased in frequency only in a subset of the
evolving replicates. We discerned different evolutionary paradigms based
on the heterogeneous genomic patterns among replicates. Redundancy and
quantitative trait (QT) paradigms fitted the experimental data better than
simulations assuming independent selective sweeps. Our results show that
natural D. simulans populations harbor a vast reservoir of adaptive
variation facilitating rapid evolutionary responses using multiple
alternative genetic pathways converging at a new phenotypic optimum. This
key property of beneficial alleles requires the modification of testing
strategies in natural populations beyond the search for convergence on the
molecular level.