Crowded growth leads to the spontaneous evolution of semistable coexistence in laboratory yeast populations

Evgeni M. Frenkel, Michael J. McDonald, J. David Van Dyken, Katya Kosheleva, Gregory I. Lang, Michael M. Desai

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Identifying the mechanisms that create and maintain biodiversity is a central challenge in biology. Stable diversification of microbial populations often requires the evolution of differences in resource utilization. Alternatively, coexistence can be maintained by specialization to exploit spatial heterogeneity in the environment. Here, we report spontaneous diversification maintained bya related but distinct mechanism: crowding avoidance. During experimental evolution of laboratory Saccharomyces cerevisiae populations, we observed the repeated appearance of "adherent" (A) lineages able to grow as a dispersed film, in contrast to their crowded "bottomdweller" (B) ancestors. These two types stably coexist because dispersal reduces interference competition for nutrients among kin, at the cost of a slower maximum growth rate. This tradeoff causes the frequencies of the two types to oscillate around equilibrium over the course of repeated cycles of growth, crowding, and dispersal. However, further coevolution of the A and B types can perturb and eventually destroy their coexistence over longer time scales. We introduce a simple mathematical model of this "semistable" coexistence, which explains the interplay between ecological and evolutionary dynamics. Because crowded growth generally limits nutrient access in biofilms, the mechanism we report here may be broadly important in maintaining diversity in these natural environments.

Original languageEnglish (US)
Pages (from-to)11306-11311
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number36
StatePublished - Sep 8 2015
Externally publishedYes


  • Coexistence
  • Crowding
  • Experimental evolution
  • Fungal adherence

ASJC Scopus subject areas

  • General


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