Nutrient stoichiometry shapes microbial coevolution

Abstract

Coevolution is a force contributing to the generation and maintenance of biodiversity. It is influenced by environmental conditions including the scarcity of essential resources, which can drive the evolution of defence and virulence traits. We conducted a long‐term chemostat experiment where the marine cyanobacterium Synechococcus was challenged with a lytic phage under nitrogen (N) or phosphorus (P) limitation. This manipulation of nutrient stoichiometry altered the stability of host–parasite interactions and the underlying mode of coevolution. By assessing the infectivity with > 18 000 pairwise challenges, we documented directional selection for increased phage resistance, consistent with arms‐race dynamics while phage infectivity fluctuated through time, as expected when coevolution is driven by negative frequency‐dependent selection. The resulting infection networks were 50% less modular under N‐ versus P‐limitation reflecting host‐range contraction and asymmetric coevolutionary trajectories. Nutrient stoichiometry affects eco‐evolutionary feedbacks in ways that may alter the dynamics and functioning of environmental and host‐associated microbial communities.

Anthropogenic global shifts in biospheric N and P concentrations and ratios and their impacts on biodiversity, ecosystem productivity, food security, and human health

“…Impacts of changes from N to P limitation on the relationships between bacteria and hosts (and vice versa) are strong due to the short life cycles of bacteria. Host selection in the cyanobacterium Synechococcus is more discriminant under N than P limitation, leading to changes in the co‐evolution of microbial communities associated with hosts that depend on intermediate N:P ratios (Larsen, Wilhelm, & Lennon, ). Similarly, changes in key ecosystem processes indirectly involved in community species composition, such as the transfer of energy and elements through trophic levels and nutrient cycling, have been correlated with changes in organismic N:P ratios (Ågren, ; Arnold et al, ; Güsewell & Gessner, ; Güsewell & Verhoeven, ; Penuelas et al, ; Vanni, Flecker, Hood, & Headworth, ; Zhang, Bai, & Han, and references therein).…”

Stoichiometric flexibility and soil bacterial communities respond to nitrogen fertilization and neighbor competition at the early stage of primary succession

“…4). Similarly, previous studies have showed that resource stoichiometry and soil microorganisms have a close relationship, and soil C:N:P stoichiometry shapes microbial coevolution, which is important for the maintenance of microbial biodiversity (Castle et al 2016;Larsen et al 2019). Generally, the growth of plants and soil microbes are limited by N, and there is competition for resources between plant roots and soil microbes under nutrient-poor conditions (e.g., N-limited environment, Wang and Bakken 1997;Kuzyakov and Xu 2013).…”

Elemental Ratios Link Environmental Change and Human Health

“…Resource stoichiometry impacts the composition and function of microbial communities across a broad suite of environments (Cherif and Loreau, 2007;Hibbing et al, 2010;Larsen et al, 2019), but this has not yet been explored in the human gut. Both dietary fiber intake (Hamaker and Tuncil, 2014) and dietary N (Holmes et al, 2017) have clear effects on gut microbial community composition and function, suggesting that dietary C:element ratios play a role in shaping the microbiome and its effects on health.…”