bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.64898/2026.10.15.759214

When should a pathogen strike? Navigating the landscape of birth pulses and mating season

Srinivasan, B.·Bruns, E.·Hulse, S. V.
View original source ↗Export metadata ↓

Abstract

Susceptibility to pathogens often differs across host life stages, which in turn depends on seasonal host phenology. For many species, juveniles are highly susceptible relative to adults, which given constrained birth periods can lead to seasonal variation in the average host susceptibility. Similarly, for pathogens with complex lifecycles, or seasonally dependent development, peak transmission may be temporally constrained. Maximum pathogen transmission may therefore coincide with a greater abundance of either juvenile or adult hosts. For instance, the birthing season presents a highly susceptible pool of hosts while the mating season presents a higher rate of contact between potentially less susceptible hosts. When these two transmission opportunities are separated in time, it is unclear whether pathogens should evolve a single, intermediate transmission timing or undergo disruptive selection to exploit different host life stages. To investigate how pathogens might navigate this complex landscape, we developed an age-structured model that allows us to test the impacts of host life history on pathogen prevalence and evolution, inspired by a fungal plant pathogen. Parameterizing the model for Silene latifolia, we find that disease prevalence is highest when seed germination coincides with flowering, and that separating the two reduces disease. Using invasion analysis, we find that at the estimated S. latifolia parameters, a single evolutionarily stable transmission timing closely tracks germination time, with infectious flowering centered about seven weeks after the median germination day. When juveniles mature faster or are much more susceptible than adults, or under parameters for Dianthus pavonius, a pathogen genotype that transmits to spring-germinating juveniles and one that transmits later in the year can instead each invade the other and coexist as a polymorphic population when germination is split between spring and summer cohorts. Our model may help explain observed phenological differences seen in wild populations of infected plants.

Explore related subjects

evolutionary biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Srinivasan, B., Bruns, E., Hulse, S. V.. 2026-10-16. When should a pathogen strike? Navigating the landscape of birth pulses and mating season. https://doi.org/10.64898/2026.10.15.759214

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

An unconstrained Euclidean parametrisation of phylogenetic tree space

Phylogenetic trees combine a discrete topology with continuous branch lengths, which makes them difficult to work with. We introduce a recursive contour-grafting construction that encodes both components using unconstrained real-valued coordinates. After fixing an order of the leaves, each new leaf is attached at a point selected by a contour traversal of the tree constructed so far. Moving a graft coordinate continuously along the contour enables changes of topology when internal branches contract to zero. For trees with n labelled leaves, we apply the construction to rooted ultrametric trees, rooted trees with unrestricted branch lengths, and unrooted trees, obtaining parametrisations of dimensions n-1, 2n-2, and 2n-3, respectively. We show that the resulting construction functions are surjective and continuous onto the corresponding spaces of phylogenetic trees. We also determine the number of representations of a generic tree and calculate the Jacobian of each parametrisation. These results provide explicit change-of-variables formulae between Euclidean coordinates and the phylogenetic tree spaces, and we show how probability distributions on tree space can be sampled using generic algorithms that target unconstrained Euclidean coordinates. This approach paves the way for the development and application of new methodology in Bayesian phylogenetic inference.

evolutionary biology↗
bioRxiv2026

Triangulating evidence to detect signatures of stabilizing selection acting on protein levels in humans

Stabilizing selection is thought to maintain quantitative traits near evolutionary optima, yet the extent to which it constrains human molecular phenotypes remains largely unknown. Here, we investigate signatures of stabilizing selection on the circulating levels of 2'923 plasma proteins in up to 50'000 UK Biobank participants by integrating complementary evidence across evolutionary timescales. We combine genetic signatures of selection accumulated over generations with associations between protein abundance and contemporary fitness-related outcomes. Genetic evidence was assessed using the frequency-dependent architecture of common variants with LDpred2 and a newly developed likelihood-based framework leveraging rare loss-of-function variant burdens. Contemporary evidence was obtained through quadratic associations between protein abundance and three fitness proxies: reproductive success, somatic health, and parental longevity. Across all approaches, negative selection coefficients predominated. Among significant estimates, 100% of common-variant and 92.4% of rare-variant estimates were consistent with stabilizing selection, compared with 99.8% for somatic health, 97.7% for parental longevity, and 89.3% for reproductive success. Despite capturing distinct aspects of selection, the approaches showed partial convergence. Rare-variant-based estimates correlated with health-score-derived coefficients (rho = 0.36, p = 5.2 x 10^-6) and independent measures of evolutionary constraint, including protein heritability, loss-of-function intolerance, and cross-species transcript evolutionary rates. Together, our findings suggest that stabilizing selection is widespread across the human plasma proteome and highlight the value of integrating genetic architecture with fitness-related phenotypes to understand evolutionary constraints on molecular variation.

evolutionary biology↗
bioRxiv2026

Strain-specific higher-order interactions break phylogenetic conservatism in microbial communities

Whether strains of the same species sharing the same ecological role are truly interchangeable has not been directly tested experimentally in communities, where higher-order interactions govern outcomes. Using 79 co-occurring Bacillaceae isolates from the Cuatrocienegas Basin, we combined whole-genome analyses with systematic strain substitutions in BARS, a three-species community in which a resistant strain protects a sensitive strain from an antagonist. Trait conservatism strongly predicted pairwise antagonistic outcomes. Yet across 34 assembled triads, 13 showed rescue beyond pairwise expectations and five showed suppression; single-strain substitutions rarely restored protection, although protection was recovered in one fully reconfigured triad. These outcomes could not be inferred from taxonomic relatedness, pangenomic content or pairwise assays; phylogenetic conservatism thus reaches its limit at the transition from pairwise to higher-order interactions. To explain this limit, we propose that strains behave as non-equivalent biological tiles whose interaction edges must align, a dynamic biological tessellation.

evolutionary biology↗