Evolutionary Biology

Evaluation Summary:

This paper is an impressive and deep look at a very important problem: understanding the genetic underpinnings of evolution acting on a quantitative trait. The authors analytically study the response to an abrupt shift in phenotypic optimum, in terms of both phenotype and genetic basis (how various alleles/loci contribute to this response). The basic assumptions are classic, but the methods and findings are new (especially finite population effects) and well supported by clear analytical approximations and extensive simulation checks. The main finding is that the relative contribution of large vs moderate effect alleles changes substantially and predictably over a long-term period after the shift, even though the phenotypic changes are already undetectable over this period.

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #1 and Reviewer #2 agreed to share their name with the authors.)

Evaluation Summary:

This paper is of interest for scientists studying human genetic adaptation and disease. The work improves on previous studies addressing the question of recent positive selection on genes underlying Mendelian diseases, by examining larger datasets of disease genes as well as carefully controlling for confounding factors that could result in disease genes and non-disease genes showing different patterns of genetic variation. The authors suggest that interference between strongly deleterious recessive mutations can reduce adaptation at disease genes, although this conclusion is weakened by the fact that the signal is only observed in Africa.

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #1 agreed to share their name with the authors.)

Evaluation Summary:

This paper documents in wild bonobos significant physiological changes in response to becoming a sibling for the first time. The authors find that new siblings' cortisol increases dramatically, while their neopterin (a marker of immune function) decreases. This paper will be of interest to those who study development, life history transitions, and colleagues at the intersection of physiology and behavior, in particular in primates and other mammals with slow life histories.

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #3 agreed to share their name with the authors.)

Evaluation Summary:

The authors use a comparative genomics approach to predict gene function, in particular genes that have a role in eye development. After identifying the convergent loss of SERPINE3 with vision loss across mammals, the authors confirmed its involvement in eye development by characterizing zebrafish knockouts. This work highlights the power of comparative genomics to generate hypotheses that can be experimentally validated. This work is relevant to a broad audience interested in evolution and adaptation as well as for those studying eye development and eye pathologies.

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #2 agreed to share their name with the authors.)

Evaluation Summary:

This manuscript describes randomly generated small proteins of <50 amino acids that can rescue the growth of an auxotrophic mutant of Escherichia coli. The authors suggest that these proteins function by binding specifically to a regulatory element in the 5' UTR of the his operon RNA, altering RNA structure to increase expression. The study suggests that functional small proteins can evolve de novo and that newly evolved small proteins can function as regulators by binding RNA. This is an exciting idea, but the suggested mechanism involving the binding of the small proteins to RNA requires additional experimental support.

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #1 and Reviewer #3 agreed to share their name with the authors.)

Evaluation Summary:

This paper combines evolution experiments with genomic analysis of environmental samples to study the evolution of colistin resistance in E. coli. It highlights the importance of pre-existing genomic variations in clinical strains in driving the evolution of antibiotic resistance. The results presented here are relevant for clinical and non-clinical microbiologists studying antibiotic resistance to last-resort drugs like colistin. The design of the research is simple and elegant, and the genomic data analysis connects the in vitro findings to the real world. However, the authors could better align the experimental and clinical data, and better clarify their experimental design choices.

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #1 and Reviewer #2 agreed to share their name with the authors.)

Evaluation Summary:

This paper will be of interest to scientists within community ecology. The authors present a mathematically solid analysis of how nonlinear constraints influence resource-competition models with trade-offs, with the conclusions being similar to those of previous studies in which trade-offs are not exact.

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #1 agreed to share their name with the authors.)

Evaluation Summary:

This work will be of interest to readers in the fields of cell biology, evolutionary biology, and biophysics. The collected data are of good quality and are properly analysed. The work thus convincingly demonstrates that energetic considerations (building costs versus potential benefit) must be taken into account to understand flagellar evolution.

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #1 agreed to share their name with the authors.)

Evaluation Summary:

This study uses the parlance and framing of the fitness landscape to articulate a co-evolution story between host and parasite. It utilizes a tractable system, bacteriophage λ and E. coli, to ask questions that unite different pillars of evolutionary theory - evolutionary genetics (via the fitness landscape analogy), co-evolution, and host-parasite interactions. The findings will be relevant to a number of audiences, and will likely spawn downstream studies that further interrogate the molecular specifics that underlie host-parasite co-evolution.

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #2 agreed to share their name with the authors.)

Evaluation Summary:

Johnson and Desai previously reported "increasing cost epistasis", where mutations tended to have more deleterious effects in higher fitness backgrounds. Here they use the same system as before to investigate adapting populations by introducing a set of 91 mutations at multiple time points. As expected, the mean fitness effect of the mutations does decline in most (but not all) populations as they adapt but the effect is weaker than in the previous work, and in another condition, mean fitness effects of mutations do not change as the populations adapt. They suggest an intriguing interpretation (among others) that the "control coefficient" of selection on growth shifts between different genetic modules over time.

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #2 agreed to share their name with the authors.)