# Nutrient levels and trade-offs control diversity in a serial dilution ecosystem

## TL;DR

This study shows that in serial dilution microbial ecosystems, metabolic trade-offs and nutrient supply levels significantly influence species diversity, revealing complex relationships that challenge universal nutrient-diversity assumptions.

## Contribution

It provides a theoretical framework demonstrating how metabolic trade-offs enable high microbial diversity in serial dilution cultures with varying nutrient supplies.

## Key findings

- High diversity is possible with metabolic trade-offs in serial dilution cultures.
- Diversity depends on nutrient amount due to an 'early-bird' effect.
- Relationships between nutrient supply and diversity are complex and context-dependent.

## Abstract

Microbial communities feature an immense diversity of species and this diversity is linked with outcomes ranging from ecosystem stability to medical prognoses. Yet the mechanisms underlying microbial diversity are under debate. While simple resource-competition models don't allow for coexistence of a large number of species, it was recently shown that metabolic trade-offs can allow unlimited diversity. Does this diversity persist with more realistic, intermittent nutrient supply? Here, we demonstrate theoretically that in serial dilution culture, metabolic trade-offs allow for high diversity. When a small amount of nutrient is supplied to each batch, the serial dilution dynamics mimic a chemostat-like steady state. If more nutrient is supplied, diversity depends on the amount of nutrient supplied due to an "early-bird" effect. The interplay of this effect with different environmental factors and diversity-supporting mechanisms leads to a variety of relationships between nutrient supply and diversity, suggesting that real ecosystems may not obey a universal nutrient-diversity relationship.