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1. Evidence for the Stability Selection Mechanism in a Live Predator–Prey System

   https://doi.org/10.1111/ele.70367  

   DeLong, John P; Coblentz, Kyle E; Montooth, Kristi L; Yang, Qingqing; Thilakarathne, Dinelka; Biagioli, Francis (March 2026, Ecology Letters)

   ABSTRACT Stability selection is the process by which species are lost from a community due to a structural susceptibility to extinction. Stability selection is non‐adaptive because it does not lead to the evolution of traits that increase individual fitness. However, stability selection could still drive evolutionary change because the stability of populations is linked to heritable traits. Here we demonstrate both phenomena with a live predator–prey system. We show that the stability properties of a predator–prey pair vary with prey genetics, indicating the potential for differential extinction to influence the genotypic makeup of populations. Second, we show that the loss of unstable predator–prey pairs in subpopulations from the overall population can lead to trait evolution in the aggregate population, providing empirical support for the stability selection mechanism. Our results indicate that community‐level processes such as predator–prey interactions can generate eco‐evolutionary change at the population scale. 

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2. Effects of mixotroph evolution on trophic transfer

   https://doi.org/10.1093/plankt/fbae053  

   Honig, Meredith A; Barbaglia, Gina S; Doyle, Margaret D; Moeller, Holly V (January 2025, Journal of Plankton Research)

   Beisner, Beatrix E (Ed.)

   Abstract Plankton form the foundation of marine food webs, playing fundamental roles in mediating trophic transfer and the movement of organic matter. Increasing ocean temperatures have been documented to drive evolution of plankton, resulting in changes to metabolic traits that can affect trophic transfer. Despite this, there are few direct tests of the effects of such evolution on predator–prey interactions. Here, we used two thermally adapted strains of the marine mixotroph (organism that combines both heterotrophy and autotrophy to obtain energy) Ochromonas as prey and the generalist dinoflagellate predator Oxyrrhis marina to quantify how evolved traits of mixotrophs to hot and cold temperatures affects trophic transfer. Evolution to hot temperatures reduced the overall ingestion rates of both mixotroph strains, consequently weakening predator–prey interactions. We found variability in prey palatability and predator performance with prey thermal adaptation and between strains. Further, we quantified how ambient temperature affects predator grazing on mixotrophs thermally adapted to the same conditions. Increasing ambient temperatures led to increased ingestion rates but declines in clearance rates. Our results for individual, pairwise trophic interactions show how climate change can alter the dynamics of planktonic food webs with implications for carbon cycling in upper ocean ecosystems. 

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3. Bacteriophage specificity is impacted by interactions between bacteria

   https://doi.org/10.1128/msystems.01177-23  

   Bisesi, Ave T; Möbius, Wolfram; Nadell, Carey D; Hansen, Eleanore G; Bowden, Steven D; Harcombe, William R (March 2024, mSystems)

   Dyson, Zoe A (Ed.)

   ABSTRACT Predators play a central role in shaping community structure, function, and stability. The degree to which bacteriophage predators (viruses that infect bacteria) evolve to be specialists with a single bacterial prey species versus generalists able to consume multiple types of prey has implications for their effect on microbial communities. The presence and abundance of multiple bacterial prey types can alter selection for phage generalists, but less is known about how interactions between prey shape predator specificity in microbial systems. Using a phenomenological mathematical model of phage and bacterial populations, we find that the dominant phage strategy depends on prey ecology. Given a fitness cost for generalism, generalist predators maintain an advantage when prey species compete, while specialists dominate when prey are obligately engaged in cross-feeding interactions. We test these predictions in a synthetic microbial community with interacting strains ofEscherichia coliandSalmonella entericaby competing a generalist T5-like phage able to infect both prey against P22vir, anS. enterica-specific phage. Our experimental data conform to our modeling expectations when prey species are competing or obligately mutualistic, although our results suggest that thein vitrocost of generalism is caused by a combination of biological mechanisms not anticipated in our model. Our work demonstrates that interactions between bacteria play a role in shaping ecological selection on predator specificity in obligately lytic bacteriophages and emphasizes the diversity of ways in which fitness trade-offs can manifest. IMPORTANCEThere is significant natural diversity in how many different types of bacteria a bacteriophage can infect, but the mechanisms driving this diversity are unclear. This study uses a combination of mathematical modeling and anin vitrosystem consisting ofEscherichia coli,Salmonella enterica, a T5-like generalist phage, and the specialist phage P22virto highlight the connection between bacteriophage specificity and interactions between their potential microbial prey. Mathematical modeling suggests that competing bacteria tend to favor generalist bacteriophage, while bacteria that benefit each other tend to favor specialist bacteriophage. Experimental results support this general finding. The experiments also show that the optimal phage strategy is impacted by phage degradation and bacterial physiology. These findings enhance our understanding of how complex microbial communities shape selection on bacteriophage specificity, which may improve our ability to use phage to manage antibiotic-resistant microbial infections. 

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4. Predator feeding rates may often be unsaturated under typical prey densities

   https://doi.org/10.1111/ele.14151  

   Coblentz, Kyle E; Novak, Mark; DeLong, John P (February 2023, Ecology Letters)

   Abstract Predator feeding rates (described by their functional response) must saturate at high prey densities. Although thousands of manipulative functional response experiments show feeding rate saturation at high densities under controlled conditions, it remains unclearhowsaturated feeding rates are at natural prey densities. The general degree of feeding rate saturation has important implications for the processes determining feeding rates and how they respond to changes in prey density. To address this, we linked two databases—one of functional response parameters and one on mass–abundance scaling—through prey mass to calculate a feeding rate saturation index. We find that: (1) feeding rates may commonly be unsaturated and (2) the degree of saturation varies with predator and prey taxonomic identities and body sizes, habitat, interaction dimension and temperature. These results reshape our conceptualisation of predator–prey interactions in nature and suggest new research on the ecological and evolutionary implications of unsaturated feeding rates. 

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5. A predator-prey model with age-structured role reversal

   https://doi.org/10.1007/s00285-026-02402-5  

   Suarez, Luis Carlos; Cameron, Maria K; Fagan, William F; Levy, Doron (May 2026, Journal of Mathematical Biology)

   Abstract We propose a predator-prey model with an age-structured predator population that exhibits a functional role reversal. The structure of the predator population in our model embodies the ecological concept of an ontogenetic niche shift, in which a species’ functional role changes as it grows. This structure adds complexity to our model but increases its biological relevance. The time evolution of the age-structured predator population is motivated by the Kermack-McKendrick Renewal Equation (KMRE). Unlike KMRE, the predator population’s birth and death rate functions depend on the prey population’s size. We establish the existence, uniqueness, and positivity of the solutions to the proposed model’s initial value problem. The dynamical properties of the proposed model are investigated via Latin Hypercube Sampling in the 15-dimensional space of its parameters. Our Linear Discriminant Analysis suggests that the most influential parameters are the maturation age of the predator and the rate of consumption of juvenile predators by the prey. We carry out a detailed study of the long-term behavior of the proposed model as a function of these two parameters. In addition, we reduce the proposed age-structured model to ordinary and delayed differential equation (ODE and DDE) models. The comparison of the long-term behavior of the ODE, DDE, and the age-structured models with matching parameter settings shows that the age structure promotes the instability of the Coexistence Equilibrium and the emergence of the Coexistence Periodic Attractor. 

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