modeled communities of bacteria in which nutrients were repeatedly added and then used up. To address this question, Erez, Lopez et al. By contrast, less is known about the way species diversity is maintained when nutrients are only intermittently available, for example in ecosystems that have seasons. Researchers have proposed many competing theories to explain how this paradox can emerge, but they have mainly focused on ecosystems where nutrients are steadily supplied. However, many natural ecosystems foster a wide array of species despite offering relatively few resources. The competitive-exclusion principle is a hypothesis which proposes that, in an ecosystem, competition for resources results in decreased diversity: only species best equipped to consume the available resources thrive, while their less successful competitors die off. The number and relative abundance of species that an ecosystem can host is referred to as ‘species diversity’. In most environments, organisms compete for limited resources. 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. If more nutrient is supplied, community diversity shifts due to an 'early-bird' effect. When a small amount of nutrient is supplied to each batch, the serial dilution dynamics mimic a chemostat-like steady state.
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. 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. Yet the mechanisms underlying microbial diversity are under debate. Microbial communities feature an immense diversity of species and this diversity is linked to outcomes ranging from ecosystem stability to medical prognoses.