PLOS Genetics study finds sexual-mode speciation in Shewanella baltica driven by stratified Baltic Sea sediment habitats
Genomic analysis of 112 Shewanella baltica strains from Baltic Sea sediment cores reveals that fine-scale spatial structure in the habitat promotes recombination-driven speciation patterns more reminiscent of sexual than clonal evolution.
A study published on 11 September 2026 in PLOS Genetics by Víctor Fernández-Juárez, Francisco Salvà-Serra, Guillem Seguí, Alberto J. Martín-Rodríguez and colleagues investigates how bacterial species boundaries form and are maintained in the stratified sediment environment of the Baltic Sea.
The researchers analysed 112 genome sequences from Shewanella baltica strains collected across multiple sediment cores and depths (0–6 cm) at Vaxön, Sweden. Their genomic analysis of this species complex — a group of closely related but distinct lineages co-occurring at fine spatial scales — found patterns of intraspecific and interspecific differentiation consistent with recombination-driven, or 'sexual', speciation rather than the strictly clonal mode traditionally associated with bacteria.
The findings contribute to understanding how microbial diversity is generated and maintained in physically structured environments, with implications for models of bacterial evolution and ecology. Shewanella baltica is not a human pathogen; the study's significance is primarily for evolutionary microbiology, microbial ecology, and educators covering concepts of speciation and bacterial population genetics.
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Primary source Public Library of Science · 2026-09-11Life in sediments fosters 'sexual' speciation in the Shewanella baltica complex