Single-cell profiling of the amphioxus digestive tract reveals scattered distribution of three endocrine-like cell clusters.

Single-cell profiling of the amphioxus digestive tract reveals scattered distribution of three endocrine-like cell clusters.

Amphioxus are small marine chordates that have broad ecological ranges, yet as adults form local settlements and exhibit limited mobility. Genomic surveys of two amphioxus species have suggested that they rank among the most genetically diverse metazoans. Here, we present the first accurate assessment of genomic diversity in the European amphioxus ( Branchiostoma lanceolatum ) and investigate the processes underlying this diversity. We leverage high-coverage whole-genome sequencing data from multiple individuals sampled at two geographically distant Atlantic and Mediterranean locations. Consistent with previous estimates in other amphioxus species, we measure exceptionally high genomic diversity, with an average heterozygosity of 2.73% in B. lanceolatum . Despite the large geographic separation between sampling sites, population differentiation is minimal, indicating extensive gene flow among distant adult settlements. Phylogenetic analyses combined with population genetic simulations confirm that this elevated genomic diversity is primarily driven by a large effective population size. Although adult amphioxus have limited mobility, our results indicate that long-distance larval dispersal mediated by ocean currents is sufficient to generate a near-panmictic population structure across their broad ecological range. ### Competing Interest Statement The authors have declared no competing interest. Swiss National Science Foundation, 207853 Agence Nationale de la Recherche, ANR-21-CE13-0034

Cephalochordates (amphioxus or lancelet) are considered as living proxies for ancestral chordates due to their key phylogenetic position and slow e...

The lateral plate mesoderm of vertebrates, which borders the other mesodermal territories, develops during embryogenesis into a variety of tissues and…

Amphioxus, or cephalochordates, have a key phylogenetic position among chordates and serve as pivotal invertebrate models for investigating the evolut…

Amphioxus (Cephalochordata) are small marine chordates that have broad ecological ranges, yet as adults form local settlements and exhibit limited mobility. Genomic surveys of two amphioxus species have suggested that they rank among the most genetically diverse metazoans. Here, we present the first accurate assessment of genomic diversity in the European amphioxus (Branchiostoma lanceolatum) and investigate the processes underlying this diversity. We leverage whole-genome sequencing data from multiple individuals sampled at two geographically distant Atlantic and Mediterranean locations. Consistent with previous estimates in other amphioxus species, we measure exceptionally high genomic diversity, with an average heterozygosity of 2.73% in B. lanceolatum. Despite the large geographic separation between sampling sites, population differentiation is minimal, indicating extensive gene flow among distant adult settlements. Phylogenetic analyses combined with population genetic simulations confirm that this elevated genomic diversity is primarily driven by a large effective population size. Although adult amphioxus have limited mobility, our results indicate that long-distance larval dispersal mediated by ocean currents is sufficient to generate a near-panmictic population structure across their broad ecological range. ### Competing Interest Statement The authors have declared no competing interest. Swiss National Science Foundation, 207853 Agence Nationale de la Recherche, ANR-21-CE13-0034

Analyses of brain single-cell transcriptomes from human, mouse, lizard, lamprey and amphioxus reveal that duplicated genes (ohnologues) played a pivotal part in early vertebrate cell-type diversification.