Microbial communities feature an immense diversity of species . Moreover, the extent of  diversity correlates with outcomes ranging from ecosystem stability to favorable medical prognoses. Yet the mechanisms underlying microbial diversity are not well understood . Simple resource-competition models do not allow for  a large number of URLanisms, permitting coexistence of only as many speciesas resources . However, it was recently shown that metabolic trade-offs can lead to unlimited diversity in a steady-state chemostat model. Do such trade-offs permit diversity under more realistic, intermittent conditions of nutrient supply? Here, we demonstrate that in serial dilution culture, metabolic trade-offs allow for arbitrarily high diversity. Surprisingly, we find that, unlike the chemostat case, diversity depends on the amount of nutrient supplied to the community. The form of this dependence , however, varies with the precision of metabolic trade-offs and the presence of cross-feeding, immigration, or evolution. The large variation seen in this simple model suggests that real ecosystems may not obey a single universal relationship between nutrient supply and diversity  .
Microbial communities feature an immense diversity of species and the extent of this diversity correlates with outcomes ranging from ecosystem stability to medical prognoses. Yet the mechanisms underlying microbial diversity are not well understood ; simple resource-competition models do not allow for coexistence of a large number of species . However, it was recently shown that metabolic trade-offs can lead to unlimited diversity in a chemostat model. Do such trade-offs permit diversity under more realistic, intermittent conditions of nutrient supply? Here, we demonstrate that in serial dilution culture, metabolic trade-offs allow for high diversity. Unlike the chemostat case, diversity depends on the amount of nutrient supplied to the community. The form of this dependence varies with the precision of trade-offs and the presence of cross-feeding, immigration, or evolution. The large variation seen in this simple model suggests that real ecosystems may not obey a single universal relationship between nutrient supply and diversity . To connect to real microbial communities, we validate our model framework against previously published Escherichia coli batch and chemostat experiments and outline potential future experiments to test the model's multispecies predictions .
R
. Moreover,
and
A
this
D
favorable
R
. Simple
; simple
A
coexistence of
R
URLanisms, permitting coexistence of only as many speciesas resources
species
D
steady-state
D
arbitrarily
R
Surprisingly, we find that, unlike
Unlike
D
, however,
D
metabolic
A
. To connect to real microbial communities, we validate our model framework against previously published Escherichia coli batch and chemostat experiments and outline potential future experiments to test the model's multispecies predictions