Biology subjects

Nabutanyi, P.

Publications and source records attributed to Nabutanyi, P..

6 recordsLinked to original sources

bioRxiv2026

Using refuge plants to manage resistance evolution and crop yield in agricultural fields

The evolution of pesticide resistance in herbivores poses a significant challenge in agriculture. A refuge strategy, where farmers plant non-toxin-treated plants to promote growth of susceptible herbivore individuals near treated plants and facilitate gene exchange between susceptible and resistant individuals, has been used in resistance management. However, we know very little about the effect of spatiotemporal fluctuations in selection pressure on resistance management. Furthermore, pests show oviposition preference and assortative mating behaviours, both of which have rarely been considered by researchers when designing resistance management strategies. Using a stochastic eco-evolutionary plant-herbivore model, we show that over a wide range of population parameters, directional changes in toxicity level and refuge frequency that reduce selection pressure for the resistance allele in the initial pest generations are much more effective for resistance management than exposing pests to a constant toxicity level and refuge frequency across pest generations. However, the exact magnitude of the effect of changing toxicity and refuge frequency relative to keeping them constant across pest generations is sensitive to underlying population parameter values. Our results show that the refuge strategy is most effective when niche choice can evolve, but assortative mating shows both negative and positive effects in resistance management. Thus, our results reveal a potential mechanism underlying the refuge strategy's successes in the field. We show how resistance allele dominance and resistance costs influence our observations, and discuss our results in the context of partial protection from directional selection and field resistance management.

evolutionary biology↗

bioRxiv2025

Individualised niches in a variable environment - Consequences for environmental change responses

O_LIIntraspecific trait variation (ITV) can be important for population performance in a variable and changing environment because individuals with different traits have different fitness responses. Furthermore, there are three mechanisms via which individuals can interact with their environment to potentially improve fitness: niche conformance, niche construction, and niche choice (NC3). These processes become increasingly important in the presence of environmental change, but there is still no mathematical modelling framework that would unite the effects of ITV and the NC3 mechanisms. C_LIO_LIIn this paper, we build a general model incorporating ITV and two of the NC3 mechanisms (niche conformance and construction, NC2) to investigate how they affect populations in a changing and variable environment via non-linear averaging. We quantify the effects of NC2 and ITV on average individual fitness using an analytical Taylor approximation and a sampling approach. C_LIO_LIOur method allows us to answer the question of what would have happened if individuals in the study system did not have ITV or did not perform NC2 mechanisms. The answer to this question depends on the curvature of the fitness function and can be estimated via the Taylor approximation. C_LIO_LIWe apply the method to two case studies: great tits adjusting their laying date to yearly changes in vegetation green-up, and a host-parasite system in which the parasite changes its environment by immunodepression of the host. In the great tits, we found a slight negative effect of ITV and a slight positive effect of niche conformance on the population fitness. In the host-parasite system, we found ITV to have no effect without niche construction, but with niche construction ITV decreased virulence. Also, niche construction had a strong negative effect on virulence. C_LIO_LIOur extension of non-linear averaging theory, combining intraspecific and environmental variation, niche conformance, and niche construction, allowed us to assess average population performance with those mechanisms at play. However, how well one can estimate such performance depends on the type of data available. This framework can be extended further to niche choice and evolution, therefore including all processes that can change the match between individuals and their environment. C_LI

ecology↗

bioRxiv2024

The role of evolving niche choice in herbivore adaptation to host plants

Individuals living in heterogeneous environments often choose microenvironments that provide benefits to their fitness. Theory predicts that such "niche choice" can promote rapid adaptation to novel environments and help maintain genetic diversity. An open question of large applied importance is how niche choice and niche choice evolution affect the evolution of insecticide resistance in phytophagous insects. We, therefore, developed an individual-based model based on phytophagous insects to examine the evolution of insecticide resistance and host plant choice via oviposition preferences. To find biologically realistic parameter ranges, we performed an empirical literature survey on insecticide resistance in major agricultural pests and also conducted a density-dependent survival experiment using potato beetles. We find that, in comparison to a scenario where individuals randomly oviposit eggs on toxic or non-toxic plants, the evolution of niche choice generally leads to slower evolution of resistance and facilitates the coexistence of different phenotypes. Our simulations also reveal that recombination rate and dominance effects can influence the evolution of both niche choice and resistance. Thus, this study provides new insights into the effects of niche choice on resistance evolution and highlights the need for more studies on the genetic basis of resistance and choice.

evolutionary biology↗

bioRxiv2021

Modeling minimum viable population size with multiple genetic problems of small populations

An important goal for conservation is to define minimum viable population (MVP) sizes for long-term persistence. Although many MVP size estimates focus on ecological processes, with increasing evidence for the role of genetic problems in population extinction, conservation practitioners have also increasingly started to incorporate inbreeding depression (ID). However, small populations also face other genetic problems such as mutation accumulation (MA) and loss of genetic diversity through genetic drift that are usually factored into population viability assessments only via verbal arguments. Comprehensive quantitative theory on interacting genetic problems is missing. Here we develop eco-evolutionary quantitative models that track both population size and levels of genetic diversity. Our models assume a biallelic multilocus genome whose loci can be under either a single or interacting genetic forces. In addition to mutation-selection-drift balance (for loci facing ID and MA), we include three forms of balancing selection (for loci where variation is lost through genetic drift). We define MVP size as the lowest population size that avoids an eco-evolutionary extinction vortex after a time sufficient for an equilibrium allele frequency distribution to establish. Our results show that MVP size decreases rapidly with increasing mutation rates for populations whose genomes are only under balancing selection, while for genomes under mutation-selection-drift balance, the MVP size increases rapidly. MVP sizes also increase rapidly with increasing number of loci under the same or different selection mechanisms until a point is reached at which even arbitrarily large populations cannot survive anymore. In the case of fixed number of loci under selection, interaction of genetic problems did not necessarily increase MVP sizes. To further enhance our understanding about interaction of genetic problems, there is need for more empirical studies to reveal how different genetic processes interact in the genome.

evolutionary biology↗

bioRxiv2021

Nonlinear averaging in 2D: intraspecific variation in two interacting species and consequences for population dynamics

Interactions between two species, e.g. between a predator species and a prey species, can often be described as the sum of many individual-by-individual interactions whose outcomes depend on the traits of the interacting individuals. These traits often vary substantially among individuals in each species, and individuals do not always interact randomly, e.g. due to plastic responses to a shared environmental factor in a heterogeneous landscape. Here we investigate the impact of intraspecific trait variation (ITV) and such interspecific trait correlations on species interactions via nonlinear averaging. Building on past models that integrate over an interaction kernel to obtain the impacts of ITV, we develop a modeling framework that allows to model arbitrary species interactions, with interspecific trait correlations as novel feature. Based on two key ingredients, a joint trait distribution and a two-dimensional interaction function, the average interaction parameters (e.g. average predation rate) can be quantified numerically, approximated using an insightful Taylor approximation, and compared to cases without ITV. We highlight two applications of our framework. First, we study the quantitative and qualitative effects of ITV and trait correlations in a simple predator-prey model and show that even in the absence of evolution, variation and trait correlations among interacting individuals can make or break the coexistence between species. Second, we use simulated field data for a predator-prey system to show how the impact of ITV on an ecological interaction can be estimated from empirical data. HighlightsO_LIWe model how intraspecific trait variation in two species affects their interaction. C_LIO_LIOur framework allows correlations between the traits of interacting individuals. C_LIO_LITrait variation and correlations can strongly affect ecological interactions. C_LIO_LITrait variation and correlations can make or break coexistence. C_LIO_LIThe effect of intraspecific trait variation can be estimated from data. C_LI

ecology↗

bioRxiv2020

Models for Eco-evolutionary Extinction Vortices and their Detection

The smaller a population is, the faster it looses genetic variation due to genetic drift. Loss of genetic variation can reduce population growth rate, making populations even smaller and more vulnerable to loss of genetic variation, and so on. Ultimately, the population can be driven to extinction by this "eco-evolutionary extinction vortex". So far, extinction vortices due to loss of genetic variation have been mainly described verbally. However, quantitative models are needed to better understand when such vortices arise and to develop methods for detecting them. Here we propose quantitative eco-evolutionary models, both individual-based simulations and analytic approximations, that link loss of genetic variation and population decline. Our models assume stochastic population dynamics and multi-locus genetics with different forms of balancing selection. Using mathematical analysis and simulations, we identify parameter combinations that exhibit strong interactions between population size and genetic variation as populations decline to extinction and match our definition of an eco-evolutionary vortex, i.e. the per-capita population decline rates and per-locus fixation rates increase with decreasing population size and number of polymorphic loci. We further highlight cues and early warning signals that may be useful in identifying populations undergoing an eco-evolutionary extinction vortex.

evolutionary biology↗