Richard P Duncan

Richard P Duncan
University of Canberra ·  Institute for Applied Ecology (IAE)

About

239
Publications
67,495
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16,167
Citations
Additional affiliations
February 2013 - present
University of Canberra
Position
  • Professor in Conservation Ecology

Publications

Publications (239)
Article
Understanding the cumulative effects of multiple stressors on biodiversity is key to managing their impacts. Stressor interactions are often studied using an additive/antagonistic/synergistic typology, aimed at identifying situations where individual stressor effects are reduced or amplified when they act in combination. Here, we analysed variation...
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Context - Improved tracking technologies increase understanding of fish movement, but care is required when comparing studies of different design. Aims - We used an approach that allowed fine-scale tracking to compare results from individual-tracking designs to simulated batch-marking designs. Methods - Adult Galaxias tantangara (a small freshwat...
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Rainfall following turtle nest construction has long been believed to increase nest survival by its effects on reducing the location cues used by nest predators. However, it is unclear if this is generally the case and if nesting turtles actively use this mechanism to increase their reproductive fitness by deliberately timing nesting to occur befor...
Preprint
Recent studies have shown the sensitivity of wild house mice to ZnP poison in Australia is significantly lower than previously assumed which may account for the reported variability in efficacy of ZnP baits used for broadacre control of house mice in grain growing regions. Under laboratory conditions ZnP-coated grains coated with a new higher dose...
Preprint
Biodiversity is declining, typically because of multiple anthropogenic stressors. Cumulative effects of multiple stressors are classified as additive, when cumulative effects are as expected from the stressor’s singular effects, synergistic when greater than additive or antagonistic when less than additive. Less attention has been given to the cons...
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Genetic differentiation and phenotypic plasticity jointly shape intraspecific trait variation, but their roles differ among traits. In short-lived plants, reproductive traits may be more genetically determined due to their impact on fitness, whereas vegetative traits may show higher plasticity to buffer short-term perturbations. Combining a multi-t...
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Context dependence is widely invoked to explain disparate results in ecology. It arises when the magnitude or sign of a relationship varies due to the conditions under which it is observed. Such variation, especially when unexplained, can lead to spurious or seemingly contradictory conclusions, which can limit understanding and our ability to trans...
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We introduce the AusTraits database - a compilation of values of plant traits for taxa in the Australian flora (hereafter AusTraits). AusTraits synthesises data on 448 traits across 28,640 taxa from field campaigns, published literature, taxonomic monographs, and individual taxon descriptions. Traits vary in scope from physiological measures of per...
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In ecological studies, the magnitude and direction of interactions among two continuous explanatory variables and are commonly evaluated by fitting a statistical model of the form , where is an interaction term that measures departure from additivity of effects. Here, we highlight three issues associated with evaluating interactions in statistical...
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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...
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Ecological processes often exhibit time lags. For plant invasions, lags of decades to centuries between species’ introduction and establishment in the wild (naturalisation) are common, leading to the idea of an invasion debt: accelerating rates of introduction result in an expanding pool of introduced species that will naturalise in the future. Her...
Article
The global threat of plant invasions to native ecosystems mandates an understanding of the mechanisms that determine invasion success. While some exotic species establish, spread and impact native ecosystems, others establish with little or no measurable impact. Competitive ability has been highlighted as a key mechanism influencing invasion succes...
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• Environmental DNA (eDNA) monitoring is a useful tool for species detection but its use in addressing management questions remains scarce. One factor limiting the use of eDNA as a routine monitoring tool is uncertainty around the potential of eDNA data to estimate species abundance. While several confounding factors limit the ability of eDNA data...
Preprint
Full-text available
Ecological processes often exhibit time lags. For plant invasions, lags of decades to centuries between species’ introduction and establishment in the wild (naturalisation) are common, leading to the idea of an invasion debt: accelerating rates of introduction result in an expanding pool of introduced species that will naturalise in the future. Her...
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The New Zealand flora has a high proportion of endemic species but has been invaded by almost the same number of non-native plant species. To support management of invasive plant species, we provide an updated inventory of New Zealand’s naturalised flora and compare it with the native flora to identify key taxonomic and functional distinctions. We...
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Plant-soil feedbacks (PSFs) have been shown to strongly affect plant performance under controlled conditions, and PSFs are thought to have far reaching consequences for plant population dynamics and the structuring of plant communities. However, thus far the relationship between PSF and plant species abundance in the field is not consistent. Here,...
Preprint
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Phenotypic plasticity can mask population genetic differentiation, reducing the predictability of trait-environment relationships. In short-lived plants, reproductive traits may be more genetically determined due to their direct impact on fitness, whereas vegetative traits may show higher plasticity to buffer short-term perturbations. Combining a m...
Preprint
Full-text available
We introduce the AusTraits database - a compilation of measurements of plant traits for taxa in the Australian flora (hereafter AusTraits). AusTraits synthesises data on 375 traits across 29230 taxa from field campaigns, published literature, taxonomic monographs, and individual taxa descriptions. Traits vary in scope from physiological measures of...
Article
Environmental flows are increasingly being used to restore degraded floodplain vegetation; however, the type of flow regime required for recovery to healthy condition can vary depending on the extent of degradation before restoration. Regulation of the River Murray has affected floodplain ecosystems at many locations, including Bottle Bend Reserve,...
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Many invasion theories invoke resource competition as the primary mechanism of invader advantage. These include Darwin's naturalization hypothesis (DNH), which treats phylogenetic similarity as a proxy for niche overlap and competitive intensity, and the evolutionary imbalance hypothesis (EIH), which suggests the phylogenetic diversity (PD) of an i...
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1. The removal of seeds by granivorous ants can affect plant recruitment through either seed loss from predation or the dispersal and recruitment of seeds that are removed but not consumed. Consequently, variation in ant selection preferences can influence patterns of seed removal and affect plant community composition, including the spread of exot...
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Stocky galaxias Galaxias tantangara is a newly‐described freshwater fish restricted to a single population, occupying a 3 km reach of a small headwater stream in the upper Murrumbidgee River catchment of south eastern Australia. Listed as critically endangered under IUCN Red List criteria, knowledge of the species’ ecology is critical for future co...
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The strength and direction of plant–soil feedbacks are commonly estimated using log response ratios. Ratios have the benefit of being readily comparable across taxa and studies, but calculating the uncertainty associated with a ratio is not always straightforward. Many studies do not report estimates of uncertainty for feedback ratios despite this...
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Successful conservation management is often based on the principle that small or declining populations can recover if we identify and remove the factors that caused them to decline in the first place. But what form will that recovery take? Theory tells us that when a strong limiting factor is removed, a population should increase in size to where i...
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There is strong evidence for a phylogenetic signal in the degree to which species share co‐evolved biotic partners and in the outcomes of biotic interactions. This implies there should be a phylogenetic signal in the outcome of feedbacks between plants and soil microbiota they cultivate. However, attempts to identify a phylogenetic signal in plant‐...
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Freshwater ecosystems and their associated biota have been negatively impacted by the human development of water resources. Fundamental to restoration activities for target species is an understanding of the factors affecting population decline or recovery. Within Australia’s Murray–Darling Basin, recovery efforts to address the population decline...
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Environmental DNA (eDNA) metabarcoding surveys enable rapid, non‐invasive identification of taxa from trace samples with wide‐ranging applications from characterising local biodiversity to identifying food‐web interactions. However, the technique is prone to error from two major sources: i) contamination through foreign DNA entering the workflow, a...
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Understanding the causes of spatial variation in the distribution and richness of alien species is a key goal of invasion biology. Thanks to the increasing availability of geographical compendia of alien species it is also the subject of a burgeoning scientific literature. Here, we review elements of this literature to argue that understanding the...
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A recent analysis by Moulton & Cropper (2019) of a global dataset on alien bird population introductions claims to find no evidence that establishment success is a function of the size of the founding population. Here, we re-analyse Moulton & Cropper’s data and show that this conclusion is based on flawed statistical methods—their data in fact conf...
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When plants establish outside their native range, their ability to adapt to the new environment is influenced by both demography and dispersal. However, the relative importance of these two factors is poorly understood. To quantify the influence of demography and dispersal on patterns of genetic diversity underlying adaptation, we used data from a...
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Bi-allelic Single Nucleotide Polymorphism (SNP) markers are widely used in population genetic studies. In most studies, sequences either side of the SNPs remain unused, although these sequences contain information beyond that used in population genetic studies. In this study, we show how these sequence tags either side of a single nucleotide polymo...
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Background: The use of environmental DNA analysis has revolutionized biodiversity monitoring. Initially, eDNA monitoring surveys in aquatic environments utilized a targeted approach, but there has been a steady shift toward whole community assessments (eDNA metabarcoding). Both approaches can increase the detection sensitivity for rare and elusive...
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Non‐native species can dominate plant communities by competitively displacing native species, or because environmental change creates conditions favourable to non‐native species but unfavourable to native species. We need to disentangle these mechanisms so that management can target competitively dominant species and reduce their impacts. Joint‐spe...
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Eradications of invasive species are usually expensive and difficult to conduct. Knowing when to declare an eradication successful requires distinguishing between failed detection of the target species due to imperfect sensitivity of the detection method and true species absence. This is difficult because the sensitivities of many detection methods...
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Alien plant pathogens are a threat to native plants and are increasingly integrating into native plant‐pathogen networks, but how these novel plant‐pathogen networks are structured remains unclear. Theory predicts that novel antagonists are likely to be generalists, resulting in interaction networks with greater nestedness as well as lower modulari...
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Karyotypic data from Australian native freshwater fishes are scarce, having been described from relatively few species. Golden perch (Macquaria ambigua) and Murray cod (Maccullochella peelii) are two large-bodied freshwater fish species native to Australia with significant indigenous, cultural, recreational and commercial value. The arid landscape...
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A key question in invasion biology is why some regions have more alien species than others. Here, we provide a general framework to answer this. We model alien species richness as a function of the number of species introduced (colonization pressure) and the probability that each species establishes, which is a function of propagule pressure (the n...
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Determining whether an alien species is at environmental equilibrium is fundamental to understanding the risk of its continued range expansion, but this is rarely quantitatively assessed. We used experimental transplants within and beyond the current elevation range (~ 0–300 m a.s.l.) of two naturalized succulent plant species, Aeonium arboreum and...
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The degree to which plant communities are vulnerable to invasion by alien species has often been assessed using the relationship between native and alien plant species richness (NAR). Variation in the direction and strength of the NAR tends to be negative for small plot sizes and study extents, but positive for large plots and extents. This invasio...
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Aim Mutualisms are often disrupted for plants introduced to new ranges, yet many of these plants have managed to obtain effective mutualistic associations in their new ranges. There are two potential pathways for non‐native plants to reassemble mutualisms: cointroduction (i.e. familiar associations with cointroduced mutualists) or ecological fittin...
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Imperfect detection can bias estimates of site occupancy in ecological surveys but can be corrected by estimating detection probability. Time‐to‐first‐detection (TTD) occupancy models have been proposed as a cost‐effective survey method that allows detection probability to be estimated from single site visits. Nevertheless, few studies have validat...
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Socio-economic factors often determine the extent to which different global regions have been invaded by non-native plant species, yet few studies examine whether such variables are similarly important for native species richness. In contrast to previous studies that have assembled regional floras for comparison, we examine global patterns of non-n...
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1.Niche availability, niche overlap and competitive ability are key determinants of the distribution and abundance of species. However, quantifying each of these components is difficult because it is not always possible to identify or measure relevant environmental gradients (niche axes) along which species might partition or compete for niche spac...
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Hybridisation and introgression are natural phenomena that may lead to the transfer of adaptive alleles from one species to another and increased species diversity. At the same time, hybridisation and subsequent introgression threaten many species world‐wide through the loss of genetic and species diversity. In Australia, introgressive hybridisatio...
Preprint
1.Non-native plant species can dominate communities by competitively excluding native species. However, quantifying the competitive impact of non-native species is difficult because they may simply be abundant where native species are not due to different environmental requirements, meaning that the effects of environmental and competitive variatio...
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Rewilding is a novel approach to ecological restoration. Trophic rewilding in particular aims to reinstate ecological functions, especially trophic interactions, through the introduction of animals. We consider the potential for trophic rewilding to address biological invasions. In this broad review, we note some of the important conceptual and eth...
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Background: Highly modified landscapes offer the opportunity to assess how environmental factors influence the integration of alien plant species into native vegetation communities and determine the vulnerability of different communities to invasion. Aims: To examine the importance of biotic and abiotic drivers in determining whether alien plant sp...
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Recent advances in passive integrated transponder (PIT) technology have led to smaller tags, meaning this technology can be used to mark and monitor smaller bodied species, many of which are threatened. This study examined the effects of 9‐mm PIT tags on the survival and growth of the Mountain Galaxias Galaxias olidus, using this fish as a surrogat...
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Global trade and the movement of people accelerate biological invasions by spreading species worldwide. Biosecurity measures seek to allow trade and passenger movements while preventing incursions that could lead to the establishment of unwanted pests, pathogens, and weeds. However, few data exist to evaluate whether changes in trade volumes, passe...
Data
List of focal host plant species and family affiliation for each production sector. (DOCX)
Data
Correlations between variables representing trade and passenger arrivals to New Zealand. (DOCX)
Data
Number of detected fungal pathogens in New Zealand compared to those observed globally for the focal host species with the 10 most pathogens in New Zealand. (DOCX)
Data
FAO commodity categories and plant family affiliation used to determine sector-specific imports. FAO, Food and Agriculture Organization. (DOCX)
Article
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Aim Changing preferences regarding which species humans have transported to new regions can have major consequences for the potential distribution of alien taxa, but the mechanisms shaping these patterns are poorly understood. We assessed the extent to which changes in human preferences for transporting and introducing alien freshwater fishes have...
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Environmental DNA (eDNA) is increasingly used to monitor aquatic macro-fauna. Typically, short mitochondrial DNA fragments are targeted because these should be relatively more abundant in the environment as longer fragments will break into smaller fragments over time. However, longer fragments may permit more flexible primer design and increase tax...
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DNA based techniques are increasingly used for measuring the biodiversity (species presence, identity, abundance and community composition) of terrestrial and aquatic ecosystems. While there are numerous reviews of molecular methods and bioinformatic steps, there has been little consideration of the methods used to collect samples upon which these...
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Mortality caused by rabbit haemorrhagic disease virus (RHDV) in wild rabbits is reduced in parts of Australia where the related, non-pathogenic calicivirus RCV-A1 is endemic. Laboratory experiments previously showed that prior infection with RCV-A1 enabled rabbits to better withstand subsequent infection with highly virulent RHDV, and this was assu...
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Information criteria (IC) are used widely for data summary and model building in ecology, especially in applied ecology and wildlife management. Although IC are useful for distinguishing among rival candidate models, IC do not necessarily indicate whether the ‘best’ model (or a model-averaged version) is a good representation of the data or whether...
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Release from natural enemies is considered an important mechanism underlying the success of plants introduced to new regions, but the degree to which alien plant species benefit from enemy release appears highly variable and context-dependent. Such variation could arise if enemy release is a transient phenomenon, whereby alien plant species initial...
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Dispersal is thought to be a key process underlying the high spatial diversity of tropical forests. Just how important dispersal is in structuring plant communities is nevertheless an open question because it is very difficult to isolate dispersal from other processes, and thereby measure its effect. Using a unique situation, the loss of vertebrate...
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Risk assessments of alien species are usually conducted at species level, assuming that all individuals of a given species pose similar risks. However, this may not be the case if there is substantial within-species variation that could influence invasion success. We used a seed addition experiment, comprising 25 taxonomically stratified varieties...
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Extinctions have altered island ecosystems throughout the late Quaternary. Here, we review the main historic drivers of extinctions on islands, patterns in extinction chronologies between islands, and the potential for restoring ecosystems through reintroducing extirpated species. While some extinctions have been caused by climatic and environmenta...
Presentation
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As identifying illegally traded taxa is often difficult through visual observations, DNA-based species identification has been routinely applied for forensic case-work. While traditional DNA barcoding utilises physical samples from individual taxa (tissue, blood, etc.), recent advances now allow us to identify species using DNA derived from environ...