Phages interact with bacteria and eukaryotic cells in ways that researchers suspect influence mammalian health.

The finding that a bacterium within a bacterium within an animal cell cooperates with the host on a biosynthetic pathway suggests the endosymbiont is, practically speaking, an organelle.

The blue lagoons of the Cuatro Ciénegas Basin provide a glimpse into the planet’s ancient past.

The ancient organisms appear to be more closely related to eukaryotes than previously appreciated.

Contrary to some hypotheses, the organelles did not descend from any known lineage of Alphaproteobacteria, researchers find.

From fish harvests to cottonwood forests, organisms display evidence that species change can occur on timescales that can influence ecological processes.

Viruses within Salmonella rapidly spread genes throughout the bacterial population during a gut infection, scientists show.

A bacterium’s ability to distinguish self from non-self can arise spontaneously, a study shows, reigniting questions of whether the trait can be considered an adaptation.

Strong selective pressure can lead to rapid and reproducible evolution in bacteria.