Pervasive fitness trade-offs revealed by rapid adaptation in large experimental populations of .

Life-history trade-offs are an inherent feature of organismal biology that evolutionary theory posits play a key role in patterns of divergence within and between species. Efforts to quantify trade-offs are largely confined to phenotypic measurements and the identification of negative genetic-correlations among fitness-relevant traits. Here, we use time-series genomic data collected during experimental evolution in large, genetically diverse populations of to directly measure the manifestation of trade-offs in response to temporally fluctuating selection pressures on ecological timescales.

Dominance reversal maintains large-effect resistance polymorphism in temporally varying environments.

A central challenge in evolutionary biology is to uncover mechanisms maintaining functional genetic variation1. Theory suggests that dominance reversal, whereby alleles subject to fluctuating selection are dominant when beneficial and recessive when deleterious, can help stabilize large-effect functional variation in temporally varying environments2,3. However, empirical evidence for dominance reversal is scarce because testing requires both knowing the genetic architecture of relevant traits and measuring the dominance effects on fitness in natural conditions4.

Continuously fluctuating selection reveals fine granularity of adaptation.

Temporally fluctuating environmental conditions are a ubiquitous feature of natural habitats. Yet, how finely natural populations adaptively track fluctuating selection pressures via shifts in standing genetic variation is unknown. Here we generated genome-wide allele frequency data every 1-2 generations from a genetically diverse population of Drosophila melanogaster in extensively replicated field mesocosms from late June to mid-December (a period of approximately 12 total generations).

Continuously fluctuating selection reveals extreme granularity and parallelism of adaptive tracking.

Temporally fluctuating environmental conditions are a ubiquitous feature of natural habitats. Yet, how finely natural populations adaptively track fluctuating selection pressures via shifts in standing genetic variation is unknown. We generated high-frequency, genome-wide allele frequency data from a genetically diverse population of in extensively replicated field mesocosms from late June to mid-December, a period of ∼12 generations.

The Consensus from the (MAP) Conference 2017.

On March 24 and 25, 2017 researchers and clinicians from around the world met at Temple University in Philadelphia to discuss the current knowledge of ssp. (MAP) and its relationship to human disease. The conference was held because of shared concern that MAP is a zoonotic bacterium that poses a threat not only to animal health but also human health.