Evolution of altruistic cooperation among nascent multicellular organisms

Abstract

Cooperation is a classic solution to hostile environments that limit individual survival. In extreme cases this may lead to the evolution of new types of biological individuals (e.g., eusocial super‐organisms). We examined the potential for interindividual cooperation to evolve via experimental evolution, challenging nascent multicellular “snowflake yeast” with an environment in which solitary multicellular clusters experienced low survival. In response, snowflake yeast evolved to form cooperative groups composed of thousands of multicellular clusters that typically survive selection. Group formation occurred through the creation of protein aggregates, only arising in strains with high (>2%) rates of cell death. Nonetheless, it was adaptive and repeatable, although ultimately evolutionarily unstable. Extracellular protein aggregates act as a common good, as they can be exploited by cheats that do not contribute to aggregate production. These results highlight the importance of group formation as a mechanism for surviving environmental stress, and underscore the remarkable ease with which even simple multicellular entities may evolve—and lose—novel social traits.

Nutrient status shapes selfish mitochondrial genome dynamics across different levels of selection

“…New levels of organization emerge when natural selection favors cooperation and the loss of conflict between previously autonomous replicating entities, giving rise to a collective unit upon which selection can further operate ( Michod et al, 2006 ; West et al, 2015 ; Queller and Strassmann, 2009 ). Cooperation thus underlies the evolution of larger, more complex biological systems ( Fisher and Regenberg, 2019 ; Gulli et al, 2019 ; Michod et al, 2006 ; West et al, 2015 ; Hammerschmidt et al, 2014 ). However, because cooperators incur the near-term cost of contributing to the fitness of others for long-term benefit, cooperation creates opportunities for the emergence of selfish ‘cheater’ entities, which show up at multiple levels of the hierarchy of biological organization.…”

Multicellular magnetotactic bacterial consortia are metabolically differentiated and not clonal

“…TA systems represent an extreme example of altruism in multicellular systems, as individual cells that contribute to the organism by sacrificing themselves through death do not directly benefit from the organism’s multicellularity. But, selection favoring altruistic traits occurs due to the fitness benefits those traits impart on relatives (50). Detection of CRISPR (clustered regularly interspaced short palindromic repeats) systems I, III-A, and III-B (SI Appendix Table S7) suggest the TA systems could be used in response to viral infection (51).…”

Multiple distinct evolutionary mechanisms govern the dynamics of selfish mitochondrial genomes

“…Cooperation and cheating represent conflicting adaptive strategies understood to shape the evolution and behavior of complex biological systems (Fisher and Regenberg, 2019, Gulli et al, 2019, Michod et al, 2006, West et al, 2015, Hammerschmidt et al, 2014). In particular, transitions toward larger, more complex forms of life occur when natural selection favors cooperation and loss of conflict between individual life forms, enabling them to become integrated into a collective entity that replicates and undergoes selection as a unified whole (Michod et al, 2006, West et al, 2015, Queller and Strassmann, 2009).…”