@article{22101,
  abstract     = {Evolutionary biology examines how the genetic and phenotypic composition
of populations changes over time. An important goal is to determine the
fixation probability of a single advantageous mutant that arises in a homogeneous
population of N residents. Many real populations experience environmental
gradients that cause mutations to be beneficial in some spatial
regions but harmful in others. Here, we study the fixation probability of a
mutant placed on a simple one-dimensional spatial structure that experiences
such a gradient. The mutant’s fitness varies linearly from1 − s to 1 + s, whereas
the resident fitness is constant and equal to 1. The existing literature suggests
that such heterogeneity in the mutant’s fitness should lead to a decrease in its
fixation probability. However, in this work, we find that small, non-negligible
gradients (s < 1=√N) substantially increase the fixation probability,while larger
gradients (s > (log N)/√N) substantially decrease it.Moreover, we quantify the
strength of this phenomenon analytically and we precisely delimit the range of
the gradients for which it occurs. Our computer simulations closely match
those findings. Altogether, our results indicate that subjecting a simple
population structure to natural environmental conditions can produce strong
counterintuitive effects.},
  author       = {Svoboda, Jakub and Nemati, Hossein and Tkadlec, Josef and Kaveh, Kamran and Chatterjee, Krishnendu},
  issn         = {2041-1723},
  journal      = {Nature Communications},
  publisher    = {Springer Nature},
  title        = {{The effect of the fitness gradient on fixation probability}},
  doi          = {10.1038/s41467-026-71777-2},
  volume       = {17},
  year         = {2026},
}