The shape of a defense-growth trade-off governs seasonal trait dynamics in natural phytoplankton

Abstract

Theory predicts that trade-offs, quantifying costs of functional trait adjustments, crucially affect community trait adaptation to altered environmental conditions, but empirical verification is scarce. We evaluated trait dynamics (antipredator defense, maximum growth rate, and phosphate affinity) of a lake phytoplankton community in a seasonally changing environment, using literature trait data and 21 years of species-resolved high-frequency biomass measurements. The trait data indicated a concave defense-growth trade-off, promoting fast-growing species with intermediate defense. With seasonally increasing grazing pressure, the community shifted toward higher defense levels at the cost of lower growth rates along the trade-off curve, while phosphate affinity explained some deviations from it. We discuss how low fitness differences of species, inferred from model simulations, in concert with stabilizing mechanisms, e.g., arising from further trait dimensions, may lead to the observed phytoplankton diversity. In conclusion, quantifying trade-offs is key for predictions of community trait adaptation and biodiversity under environmental change.

Seasonal Variations in the Biodiversity, Ecological Strategy, and Specialization of Diatoms and Copepods in a Coastal System With Phaeocystis Blooms: The Key Role of Trait Trade-Offs

“…The association between the defensive trait and cell biovolume was consistent with this functional trait trade-off (Figure 4A). To invest in defensive traits against predation, is generally metabolically costly, in such a way that prey with high defense levels has generally lower maximum growth rate, maximum resource uptake, and/or resource uptake affinity (Pančić and Kiørboe, 2018;Cadier et al, 2019;Ehrlich et al, 2020), all these types of defense costs being related to cell biovolume (Litchman and Klausmeier, 2008;Marañón, 2015).…”

Functional trait‐based approaches as a common framework for aquatic ecologists

“…Comparison of how such relationships that trade-off (i.e., negatively related) change under different abiotic or biotic conditions will allow determination of how flexible such trade-offs are as ecological conditions change. Recently, the shape of the trade-off curve, representing the boundary of the set of feasible trait combinations, has been described as explaining traits of co-existing species and changes in trait values along environmental gradients (Ehrlich et al 2017(Ehrlich et al , 2020. Convex trade-offs would facilitate the coexistence of specialized species with extreme trait values while concave trade-offs would promote species with intermediate trait values.…”

Herbivore‐induced defenses are not under phylogenetic constraints in the genusQuercus(oak): Phylogenetic patterns of growth, defense, and storage

“…Ackerly Physiology and genetics are two well-studied sources of constraints on adaptations of plant defenses (e.g., Ballaré & Austin, 2019;Endara et al, 2017;Keith, 2017;Ochoa-Lopez et al, 2018). Studies focusing on genetic constraints of adaptation often fail to consider limitation and assimilation capacity of resources (Ballaré & Austin, 2019;Mole, 1994), just as studies of physiological constraints often fail to evaluate heritability of traits (Ehrlich et al, 2020;Ward et al, 2012 TA B L E 3 ANOVA results of the effects of location and intensity on oak growth, defenses, and nutrient allocation Züst & Agrawal, 2017). For example, certain plant defenses have been shown to trade-off with plant growth or reproduction within individual species, but general patterns of plant defense trade-offs are less frequently recorded across related species (Agrawal & Fishbein, 2006;Peiman & Robinson, 2017;Züst & Agrawal, 2017;Züst et al, 2015).…”