Biology subjects

Antonovics, J.

Publications and source records attributed to Antonovics, J..

7 recordsLinked to original sources

bioRxiv2026

The consequences of mixed-mode transmission for disease prevalence

Host-parasite relationships are defined by transmission. Transmission takes diverse forms, with horizontal transmission modes generally characterized as density- or frequency-dependent. However, many observed parasites display mixed-mode transmission using both density- and frequency-dependent routes. To investigate how mixed-mode transmission impacts epidemics, we assessed infection prevalence under single- and mixed-mode transmission when there was a linear trade-off between the probability of infection by the two modes. Our results show that the prevalence of a parasite with mixed-mode transmission can be greater than one with a single-mode only when density- and frequency-dependent routes are associated with different effects of the parasite on host fitness. This work shows that mixed transmission modes per se may not necessarily increase disease prevalence, and that substituting two transmission modes for a single one may result in higher prevalence under limited conditions.

ecology↗

bioRxiv2026

Rapid evolution in necromass use under resource limitation reduces persistence in producer-decomposer microbial biospheres

This study employs a synthetic microbial biosphere model to investigate system persistence under resource limitation. Escherichia coli (E. coli) strain MC4100 was incubated in matter-closed systems in an isotonic saline solution without added nutrients for 60 days in spatially homogeneous or heterogeneous conditions. We observed phenotypic adaptive changes in E. coli populations, including loss of motility, enhanced biofilm formation, and improved growth on various carbon sources, which were specific to the spatial structure conditions. While these changes were beneficial for E. coli persistence in monoculture, during co-culture with the alga Chlamydomonas reinhardtii the adapted populations exhibited a 25% reduction in persistence under spatially heterogeneous conditions compared to co-cultures containing non-adapted E. coli populations. Critically, adaptive changes in monoculture affected the dynamics of co-cultures, demonstrating that microbial evolution can constrain coexistence with other species and may be a fundamental determinant of ecosystem sustainability.

ecology↗

bioRxiv2025

Disentangling genetic variance for pathogen avoidance and resistance

Hosts can use avoidance (e.g., behavior) to reduce their contact rates with pathogens; after contact, they can use resistance (e.g., immunity) to reduce the establishment and proliferation of an infection. Because both defenses preserve host fitness and reduce pathogen fitness, we expect that their epidemiological and evolutionary effects will be inter-dependent. This study used a two-locus model to understand the evolution of allelic associations (i.e., linkage disequilibrium) between genes determining levels of avoidance and resistance in the presence of an infectious disease or parasite. We found that polymorphism in both avoidance and resistance was possible, but only for a limited range of parameter values of avoidance and resistance; at equilibrium, avoidance and resistance alleles were negatively associated in these polymorphic populations. However, most commonly, whichever defense was more effective and less costly went to fixation. This result suggests that avoidance and resistance may be more likely to covary negatively across than within populations.

evolutionary biology↗

bioRxiv2024

Spatial structure affects the establishment and persistence of closed microbial ecosystems

Why Earth has remained habitable for billions of years is a question that has long fostered debate in biology and earth sciences. Closed systems approaches have yielded information about the underlying mechanisms, including the persistence of matter recycling. However, the majority of these studies have been conducted under relatively homogenous conditions using aquatic systems. Here, we investigated the effect of spatial structure and heterogeneity on the persistence or failure of closed microbial biospheres. This mimics unsaturated soil-like conditions that were inoculated with a two species producer-decomposer community. Specifically, we investigated how microhabitat physical structure and necromass spatial distribution affected population dynamics and system time-to-failure. We observed strong effects of microhabitat structure, including particle size and moisture level, on persistence at both the population and system levels. Systems containing the smallest substrate particles failed quickly and on average did not support decomposer populations except at high initial cell densities. Persistence was promoted by larger substrate particles, likely due to larger pore sizes resulting in shorter movement distances and better accessibility to resource patches (i.e. necromass). Building on these findings, we manipulated necromass patch distribution and observed that algae clustered around necromass patches when present. Necromass patch distribution had small but significant effects on persistence, with lower persistence in intermediate vs. high or low necromass heterogeneity. Together these findings indicate a limit to the spatial/physical parameter space in which producer-decomposer communities can establish and self-sustain via self-recycling of necromass.

ecology↗

bioRxiv2023

Host-pathogen coevolution promotes the evolution of general, broad-spectrum resistance and reduces foreign pathogen spillover risk

Genetic variation for disease resistance within host populations can strongly impact the spread of endemic pathogens. In plants, recent work has shown that within-population variation in resistance can also affect the transmission of foreign spillover pathogens if that resistance is general. However, most hosts also possess specific resistance mechanisms that provide strong defenses against coevolved endemic pathogens. Here we use a modeling approach to ask how antagonistic coevolution between hosts and their endemic pathogen at the specific resistance locus can affect the frequency of general resistance, and therefore a hosts vulnerability to foreign pathogens. We develop a two-locus model with variable recombination that incorporates both general (resistance to all pathogens) and specific (resistance to endemic pathogens only). We find that introducing coevolution into our model greatly expands the regions where general resistance can evolve, decreasing the risk of foreign pathogen invasion. Furthermore, coevolution greatly expands which conditions maintain polymorphisms at both resistance loci, thereby driving greater genetic diversity within host populations. This genetic diversity often leads to positive correlations between host resistance to foreign and endemic pathogens, similar to those observed in natural populations. However, if resistance loci become linked, the resistance correlations can shift to negative. If we include a third, linkage modifying locus into our model, we find that selection often favors complete linkage. Our model demonstrates how coevolutionary dynamics with an endemic pathogen can mold the resistance structure of host populations in ways that affect its susceptibility to foreign pathogen spillovers, and that the nature of these outcomes depends on resistance costs, as well as the degree of linkage between resistance genes.

evolutionary biology↗

bioRxiv2022

Multimodal disease transmission as a limiting factor for the spatial extent of a host plant

Theoretical models suggest that infectious diseases could play a substantial role in determining species ranges, but few studies have collected the empirical data required to test this hypothesis. Pathogens that sterilize their hosts or spread through frequency-dependent transmission could have especially strong effects on the limits of species distributions because sterilized hosts can serve as long-lived disease reservoirs and frequency-dependent transmission mechanisms are effective even at very low population densities. We collected spatial disease prevalence data and population abundance data for alpine carnations infected by the sterilizing pathogen M. violaceum, a disease that is spread through both frequency-dependent (vector-borne) and density-dependent (aerial spore transmission) mechanisms. Our 13-year study reveals rapid declines in population abundance without a compensatory decrease in disease prevalence. We apply a stochastic, spatial model of disease spread that accommodates spatial habitat heterogeneity to investigate how the population dynamics depend on multimodal (frequency-dependent and density-dependent) transmission. We found that the observed rate of population decline can be readily explained by multimodal transmission, but is unlikely to be explained by either frequency-dependent or density-dependent mechanisms alone. Multimodal disease transmission rates high enough to explain the observed decline predicted that eventual local extinction of the host species is highly likely. Our results add to a growing body of literature showing how multimodal transmission can constrain species distributions in nature. Open ResearchAll scripts associated with the analyses in this manuscript, as well as the data we collected, are available at https://github.com/uricchio/antherSmutDis.

ecology↗

bioRxiv2020

Evolution of behavioral resistance in host-pathogen systems

Behavioral resistance to parasites is widespread in animals, yet little is known about the evolutionary dynamics that have shaped these strategies. We show that theory developed for the evolution of physiological parasite resistance can only be applied to behavioral resistance under limited circumstances. We find that accounting explicitly for the behavioral processes, including the detectability of infected individuals, leads to novel dynamics that are strongly dependent on the nature of the costs and benefits of social interactions. As with physiological resistance, the evolutionary dynamics can also lead to mixed strategies that balance the costs of disease risk and the benefits of social interaction, with implications for understanding avoidance strategies in human disease outbreaks.

animal behavior and cognition↗