Biology subjects

Phillips, B.

Publications and source records attributed to Phillips, B..

5 recordsLinked to original sources

bioRxiv2018

Bangers and cash: Baiting efficiency in a heterogeneous population.

O_LIContext: The uptake of baits is a key variable in management actions aimed at the vaccination, training, or control of many vertebrate species. Increasingly, however, it is appreciated that individuals of the target species vary in their likelihood of taking baits. To optimise a baiting program, then, we require knowledge, not only on the rate of bait uptake, and how this changes with bait availability, but also knowledge on the proportion of the target population that will take a bait.\nC_LIO_LIThe invasive cane toad (Rhinella marina) is a major threat to northern quolls (Dasyurus hallucatus), which are poisoned when they attack this novel toxic prey item. Conditioned taste aversion baits (cane toad sausages) can be delivered in the field to train individual northern quolls to avoid toads.\nC_LIO_LIMethods: Here we report on a large-scale field trial across eleven sites across one large property in Western Australia. Camera trapping and statistical modelling was used to estimate the proportion of baitable animals in the population, and the proportion of these that were baited at varying bait availabilities.\nC_LIO_LIResults: Population estimates varied at each site from 3.5 ({+/-}0.76 SD) to 18 ({+/-} 1.58 SD) individual quolls per site, resulting in a range across sites of 0.6-4 baits available per individual. Bait uptake increased with increasing bait availability.\nC_LIO_LIWe also estimate that only 62% of individual quolls are baitable, and that a baiting rate of 3 baits per individual (rather than per area) will result in almost all of these baitable individuals being treated.\nC_LIO_LIWe compared our statistical method with prior data informing the probability of being baitable; and with probability of being baitable set to 1; this resulted in largely differing estimates in relation to an appropriate baiting rate.\nC_LIO_LISynthesis and applications: Data and models such as ours provide wildlife managers with information critical to informed decision making and are fundamental to estimate the cost-efficiency of any baiting campaign.\nC_LI

ecology↗

bioRxiv2018

How many, and when? Optimising targeted gene flow for a step change in the environment

Targeted gene flow is an emerging conservation strategy that involves translocating individuals with particular traits to places where they are of benefit, thereby increasing a populations evolutionary resilience. While the idea can work in theory, questions remain as to how best to implement it. Here, we vary timing of introduction and size of the introduced cohort to maximise our objective - survival of the recipient populations genome. We demonstrate our approach using the northern quoll, an Australian marsupial predator threatened by the toxic cane toad. We highlight a general trade-off between maintaining a local genome and reducing population extinction risk, but show that key management levers can optimise this so that 100% of the populations genome is preserved. In our case, any action was better than not acting at all (even with strong outbreeding depression), but the size of the benefit was sensitive to timing and size of the introduction.

ecology↗

bioRxiv2017

The population genetics of spatial sorting

In most systems, dispersal occurs despite clear fitness costs to dispersing individuals. Theory posits that spatial heterogeneity in habitat quality pushes dispersal rates to evolve towards zero, while temporal heterogeneity in habitat quality favours non-zero dispersal rates. One aspect of dispersal evolution that has received a great deal of recent attention is a process known as spatial sorting, which has been referred to as a \"shy younger sibling\" of natural selection. More precisely, spatial sorting is the process whereby variation in dispersal ability is sorted along density clines and will, in nature, often be a transient phenomenon. Despite this transience, spatial sorting is likely a general mechanism behind non-zero dispersal in spatiotemporally varying environments. While generally transient, spatial sorting is persistent on invasion fronts, where its effect cannot be ignored, causing rapid evolution of traits related to dispersal. Spatial sorting is described in several elegant models, yet these models require a high level of mathematical sophistication and are not accessible to most evolutionary biologists or their students. Here, we frame spatial sorting in terms of the classic haploid and diploid models of natural selection. We show that, on an invasion front, spatial sorting can be conceptualized precisely as selection operating through space rather than (as with natural selection) time, and that genotypes can be viewed as having both spatial and temporal aspects of fitness. The resultant model is strikingly similar to classic models of natural selection. This similarity renders the model easy to understand (and to teach), but also suggests that many established theoretical results around natural selection could apply equally to spatial sorting.

evolutionary biology↗

bioRxiv2017

Not such silly sausages: Northern quolls exhibit aversion to toads after training with toad sausages.

The invasion of toxic cane toads (Rhinella marina) is a major threat to northern quolls (Dasyurus hallucatus) which are poisoned when they attack this novel prey item. Quolls are now endangered as a consequence of the toad invasion. Conditioned taste aversion can be used to train individual quolls to avoid toads, but we currently lack a training technique that can be used at a landscape scale to buffer entire populations from toad impact. Broad scale deployment requires a bait that can be used for training, but there is no guarantee that such a bait will ultimately elicit aversion to toads. Here we test a manufactured bait--a toad sausage--for its ability to elicit aversion to toads in northern quolls. To do this, we exposed one group of quolls to a toad sausage and another to a control sausage and compared the quolls predatory responses when presented with a dead adult toad. Captive quolls that consumed a single toad sausage showed substantially reduced interest in cane toads, interacting with them for less than half the time of their untrained counterparts and showing substantially reduced attack behaviour. We also quantified bait uptake in the field, by both quolls and non-target species. These field trials showed that wild quolls were the most frequent species attracted to the baits, and that approximately 61% of quolls consumed toad-aversion baits when first encountered. Between 40-68% of these animals developed aversion to further bait consumption. Our results suggest that toad-aversion sausages can be used to train wild quolls to avoid cane toads. This opens the possibility for broad-scale quoll training with toad aversion sausages: a technique that may allow wildlife managers to prevent quoll extinctions at a landscape scale.

ecology↗

bioRxiv2017

Using Connectivity To Identify Climatic Drivers Of Local Adaptation

This preprint has been reviewed and recommended by Peer Community In Evolutionary Biology (http://dx.doi.org/10.24072/pci.evolbiol.100034). Despite being able to conclusively demonstrate local adaptation, we are still often unable to objectively determine the climatic drivers of local adaptation. Given the rapid rate of global change, understanding the climatic drivers of local adaptation is vital. Not only will this tell us which climate axes matter most to population fitness, but such knowledge is critical to inform management strategies such as translocation and targeted gene flow. While simple assessments of geographic trait variation are useful, geographic variation (and its associations with environment) may represent plastic, rather than evolved, differences. Additionally, the vast number of trait-environment combinations makes it difficult to determine which aspects of the environment populations adapt to. Here we argue that by incorporating a measure of landscape connectivity as a proxy for gene flow, we can differentiate between trait-environment relationships underpinned by genetic differences versus those that reflect phenotypic plasticity. By doing so, we can rapidly shorten the list of trait-environment combinations that may be of adaptive significance. We demonstrate how this reasoning can be applied using data on geographic trait variation in a lizard species from Australia's Wet Tropics rainforest. Our analysis reveals an overwhelming signal of local adaptation for the traits and environmental variables we investigated. Our analysis also allows us to rank environmental variables by the degree to which they appear to be driving local adaptation. Although encouraging, methodological issues remain: we point to these issue in the hope that the community can rapidly hone the methods we sketch here. The promise is a rapid and general approach to identifying the environmental drivers of local adaptation.

evolutionary biology↗