Phage therapy is a promising alternative to antibiotics to treat multidrug resistant infections. Plasmid dependent phages (PDPs) are particularly attractive as therapeutics because they can both kill ...

In this TrendsTalk series 'Disability in ecology and evolution' in Trends in Ecology and Evolution, we will be hearing from people about their experiences being disabled in ecology and evolution. We a...

Are you an alum from one of the 9 schools Trump just attacked? Sign this alumni petition now to support your school, defend democracy, and build a grassroots movement for campus freedom across America...

Safe gain-of-function research is necessary to identify new treatments for diseases like for tuberculosis — but the NIH has imposed unfounded stops.

An Open Letter to U.S. STEM Leadership on the NSF Graduate Research Fellowship Program

LexicMap uses a fixed set of probes to efficiently query gene sequences for fast and low-memory alignment.

Antibiotic resistance is frequently observed shortly after the clinical introduction of an antibiotic. Whether and how frequently that resistance occurred before the introduction is harder to determin...

NIAID’s Integrated Research Facility is one of the few federal facilities charged with studying Ebola. Tuesday afternoon, all of its work was put on indefinite pause by Robert F. Kennedy Jr.’s departm...

The rise of antibiotic-resistant bacteria, particularly multidrug-resistant Pseudomonas aeruginosa (P. aeruginosa), represents a critical challenge to…

The end of an era.

Elizabeth Jacobs, PhD, shares her story of encountering online vaccine misinformation in the early 2000's, and how she used her scientific training to uncover the truth.

On 5 May 2025, the White House issued Executive Order (EO) 14292, titled “Improving the Safety and Security of Biological Research,” framing it as a sweeping directive to strengthen biosafety and bios...

Bacterial flagella drive motility and chemotaxis while also playing critical roles in host-pathogen interactions, as their oligomeric subunit, flagellin, is specifically recognized by the mammalian im...

In simple microbial populations, the fitness effects of most selected mutations are generally taken to be constant, independent of genotype frequency. This assumption underpins predictions about evolutionary dynamics, epistatic interactions, and the maintenance of genetic diversity in populations. Here, we systematically test this assumption using beneficial mutations from early generations of the Escherichia coli Long-Term Evolution Experiment (LTEE). Using flow cytometry-based competition assays, we find that frequency-dependent fitness effects are the norm rather than the exception, occurring in approximately 80\% of strain pairs tested. Most competitions exhibit negative frequency-dependence, where fitness advantages decline as mutant frequency increases. Furthermore, we demonstrate that the strength of frequency-dependence is predictable from invasion fitness measurements, with invasion fitness explaining approximately half of the biological variation in frequency-dependent slopes. Additionally, we observe violations of fitness transitivity in several strain combinations, indicating that competitive relationships cannot always be predicted from fitness relative to a single reference strain alone. Through high-resolution measurements of within-growth cycle dynamics, we show that simple resource competition explains a substantial portion of the frequency-dependence: when faster-growing genotypes dominate populations, they deplete shared resources more rapidly, reducing the time available for fitness differences to accumulate. Our results demonstrate that even in a simple model system designed to minimize ecological complexity, subtle ecological interactions between closely related genotypes create frequency-dependent selection that can fundamentally alter evolutionary dynamics. ### Competing Interest Statement The authors have declared no competing interest.