Biology subjects

Duncan, R. P.

Publications and source records attributed to Duncan, R. P..

3 recordsLinked to original sources

bioRxiv2024

Background food influences rate of encounter and efficacy of rodenticides in wild house mice

O_LIBaiting is widely used in wildlife management for various purposes, including lethal control, fertility control, disease and parasite control, and conditioned aversion programs for many invasive vertebrate species. The efficacy of baiting programs relies on the likelihood that target animals will encounter the bait, consume it, and receive an appropriate dose of the active ingredient. However, there has been little focus on encounter rate of toxic baits combined with behavioural aversion, which are likely to be significant factors affecting efficacy. C_LIO_LIThe likelihood of an animal encountering and consuming a toxic grain bait should theoretically increase in proportion to its availability relative to background food quantity if it is neither more or less detectable or palatable. Furthermore, the probability of consuming toxic baits might also be influenced by bait aversion following ingestion of a non-lethal dose of toxin. C_LIO_LIUsing a model system of wild house mice (Mus musculus L.) in mouse-proof enclosures in Australia, we manipulated background food, applied zinc phosphide (ZnP) baits and measured the mortality of mice. When background food was scarce, mouse mortality was high, whereas an increasing abundance of background food led to reduced mortality. A scenario modelling random encounters and including bait aversion explained 78% of the variation in observed mortality outcomes and achieved a closer fit to the data. Mortality rates were predicted to be higher with a higher strength bait which overcomes behavioural aversion. C_LIO_LIEnsuring that animals locate and consume a lethal dose of toxic bait is a critical factor for successful bait delivery and efficacy. This is particularly significant in toxic baiting programs, where sublethal doses can make animals feel sick, leading to a negative association with the bait, and the development of aversion. C_LIO_LISynthesis and applications: Our findings explain why some toxic baiting programs might fail. To achieve successful control, efforts should be directed at reducing the availability of background food to increase the probability of encounter and uptake of toxic baits. It is important to measure and understand the role of background food on toxic baiting programs to explain variable outcomes and inform strategies for successful bait delivery. C_LI Graphical abstractOur findings explain why some toxic baiting programs might fail. To achieve successful control, efforts should be directed at reducing the availability of background food to increase the probability of encounter and uptake of toxic baits. It is important to measure and understand the role of background food on toxic baiting programs to explain variable outcomes and inform strategies for successful bait delivery. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/573962v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@df4b66org.highwire.dtl.DTLVardef@1cf1910org.highwire.dtl.DTLVardef@17680eeorg.highwire.dtl.DTLVardef@10ac688_HPS_FORMAT_FIGEXP M_FIG C_FIG

ecology↗

bioRxiv2021

slimr: An R package for integrating data and tailor-made population genomic simulations over space and time

Software for realistically simulating complex population genomic processes is revolutionizing our understanding of evolutionary processes, and providing novel opportunities for integrating empirical data with simulations. However, the integration between simulation software and software designed for working with empirical data is currently not well developed. Here we present slimr, an R package designed to create a seamless link between standalone software SLiM 3.0, one of the most powerful population genomic simulation frameworks, and the R development environment, with its powerful data manipulation and analysis tools. We show how slimr facilitates smooth integration between genetic data, ecological data and simulation in a single environment. The package enables pipelines that begin with data reading, cleaning, and manipulation, proceed to constructing empirically-based parameters and initial conditions for simulations, then to running numerical simulations, and finally to retrieving simulation results in a format suitable for comparisons with empirical data - aided by advanced analysis and visualization tools provided by R. We demonstrate the use of slimr with an example from our own work on the landscape population genomics of desert mammals, highlighting the advantage of having a single integrated tool for both data analysis and simulation. slimr makes the powerful simulation ability of SliM 3.0 directly accessible to R users, allowing integrated simulation projects that incorporate empirical data without the need to switch between software environments. This should provide more opportunities for evolutionary biologists and ecologists to use realistic simulations to better understand the interplay between ecological and evolutionary processes.

evolutionary biology↗

bioRxiv2019

Horizontal transfer of prokaryotic cytolethal distending toxin B genes to eukaryotes

Cytolethal distending toxins (CDTs) are tripartite eukaryotic genotoxins encoded in diverse bacterial and phage genomes. The cdtB subunit is a DNAse that causes eukaryotic cell cycle arrest and apoptosis, and in one context, is associated with resistance against parasitoid wasp infections. Here we report the discovery of functional cdtB copies in the nuclear genomes of insect species from two distantly related insect orders, including fruit flies (Diptera: Drosophilidae) and aphids (Hemiptera: Aphididae). Insect cdtB copies are most closely related to bacteriophage copies, were horizontally transferred to insect genomes > 40 million years ago and encode a protein that retains ancestral DNase activity. This phage-derived toxin has been domesticated by diverse insects and we hypothesize that it is used as a defensive weapon against parasitoid wasps. One Sentence SummaryWe report horizontal transfer of the gene cytolethal distending toxin B, which encodes a DNase, into eukaryotic genomes from bacteriophage. SignificanceCytolethal distending toxins (CDTs) are secreted by diverse pathogenic bacterial species to kill animal cells. The cdtB subunit enters cell nuclei, damaging the DNA and leading to mitotic arrest and apoptosis. In the pea aphid, a bacterial endosymbiont provides protection against wasp attack, possibly via cdtB. We discovered that this same endosymbiont-encoded lineage of cdtB was transferred to the genomes of Diptera and Hemiptera species and retains ancestral DNase activity. This is the first report of cdtB outside of bacteria or phages. A toxin that first evolved to kill eukaryotic cells has been co-opted by insects, potentially to their benefit.

evolutionary biology↗