  Biofilms are microbial collectives that occupy a diverse array of surfaces.
The function and evolution of biofilms are strongly influenced by the spatial
arrangement of different strains and species within them, but how
spatiotemporal distributions of different genotypes in biofilm populations
originate is still underexplored. Here, we study the origins of biofilm genetic
structure by combining model development, numerical simulations, and
microfluidic experiments using the human pathogen Vibrio cholerae. Using
spatial correlation functions to quantify the differences between emergent cell
lineage segregation patterns, we find that strong adhesion often, but not
always, maximizes the size of clonal cell clusters on flat surfaces.
Counterintuitively, our model predicts that, under some conditions, investing
in adhesion can reduce rather than increase clonal group size. Our results
emphasize that a complex interaction of fluid flow and cell adhesiveness can
underlie emergent patterns of biofilm genetic structure. This structure, in
turn, has an outsize influence on how biofilm-dwelling populations function and
evolve.
