84 research outputs found
Preventing biological invasions by understanding the processes leading to establishment
No full textInvasive species are a leading cause of animal extinctions and result in billions of dollars ($US) in economic damages globally. Understanding the processes involved in biological invasions can aid in finding efficient and effective policy and management solutions. In this dissertation, I explore three mechanisms that can prevent invasive species from establishing. First, within the context of the most common pathway for invasive vertebrate species, I document factors related to the release of exotic pets into the wild by their owners. Second, I develop a method to calculate the reduction of propagule pressure required to lower the establishment probability for introduced non-native populations. Last, I explore an overlooked assumption of the propagule pressure effect and calculate the how establishment probability is altered when spatial and temporal independence of introduction events is violated. The results I highlight, and the methods I developed, are critical in slowing the rate at which invasive species are establishing worldwide.Ph.D.Includes bibliographical referencesby Oliver C. Stringha
ocstringham/propagule_pressure_sensitivity_analysis: Propagule Pressure Sensitivity Analysis v1.0
No full textCode and data associated with "Managing propagule pressure to prevent invasive species establishments: propagule size, number, and risk-release curve
Identifying recent captive escapees of Rainbow Lorikeets (Trichoglossus moluccanus) at different stages of the pet-release pathway
No full textIntroduction: Rainbow Lorikeets (Trichoglossus moluccanus) are a highly desirable bird in Australian pet trade and consequently have established invasive populations outside their native range. These birds are aggressive, outcompete native species, and cause significant damage to agriculture. Invasive populations have not been impacted by existing management practices, and it is unclear if their persistence is due to their high reproductive success in the wild, or from regular escapes from captivity. Methods: We tested the ability of stable isotope analysis to identify recently escaped captive Rainbow Lorikeets in wild populations within Australia. We compared the stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopes of captive birds to three wild populations at different stages of the pet-release pathway: (i) birds within their native distribution; (ii) a newly established population; and (iii) a large invasive population. Results: We found evidence of two escaped captive birds in the newly established population due to the higher and more variable δ¹³C, which is likely driven by the consumption of nectar supplements. The invasive population had a similar isotopic niche area to the native population; potentially indicating the invasive birds have adapted to the environment and learnt to consume a large variety of local food sources, therefore reducing the effectiveness of detecting recent escapees. Discussion: Therefore, for contained wild populations with small isotopic niches, stable isotope analysis can be a useful tool to identify captive escapees and can inform management of invasive species incursions.Katherine G.W. Hill, Steven Delean, Susan A. Robinson, Tony Hall, Jonathan J. Tyler, Oliver C. Stringham, and Phillip Casse
Who's a pretty bird? Predicting the traded abundance of bird species in Australian online pet trade
No full textPublished online: 16 December 2023The increasing popularity of online commerce provides a new opportunity to investigate and quantify the dynamics of pet trade. Understanding these dynamics, including relationships between species characteristics and a species’ relative abundance in trade, can assist in informing trade regulation for conservation and biosecurity. We identified the leading correlates behind the abundance in the Australian pet trade of parrot (Psittaciformes) and passerine (Passeriformes) species. We examined 14,000 online sales of parrots and passerines collected from a popular online Australian marketplace in 2019 (representing 235 species) using an automated data collection method. We identified the characteristics that correlated with online species abundance; including (i) breeding and handling requirements; (ii) trade and availability; and (iii) appearance and behaviour. We found 55% of parrot species and 64% of passerine species traded online were non-native to Australia; of these, 81% and 85% respectively have an extreme risk of establishing invasive populations. Species abundance of both orders was correlated with cheaper prices, which is also associated with a higher invasion risk. Trade in parrots was correlated with attractive birdsongs, being easier to care for, and a preference for native Australian species. Passerine abundance was correlated with attractive plumage colour and, to a lesser extent, the availability of colour mutations and smaller geographic range sizes. These results, combined with an understanding of consumer behaviour and international trends, may help predict which species will become abundant in domestic trade in the future, and identify current and future invasion risks to assist in environmental biosecurity efforts.Katherine G. W. Hill, Oliver C. Stringham, Stephanie Moncayo, Adam Toomes, Jonathan J. Tyler, Phillip Cassey, Steven Delea
Managing propagule pressure to prevent invasive species establishments: propagule size, number, and risk–release curve
No full textHundreds of variants clustered in genomic loci and biological pathways affect human height
No full textMost common human traits and diseases have a polygenic pattern of inheritance: DNA sequence variants at many genetic loci influence the phenotype. Genome-wide association (GWA) studies have identified more than 600 variants associated with human traits(1), but these typically explain small fractions of phenotypic variation, raising questions about the use of further studies. Here, using 183,727 individuals, we show that hundreds of genetic variants, in at least 180 loci, influence adult height, a highly heritable and classic polygenic trait(2,3). The large number of loci reveals patterns with important implications for genetic studies of common human diseases and traits. First, the 180 loci are not random, but instead are enriched for genes that are connected in biological pathways (P = 0.016) and that underlie skeletal growth defects (P<0.001). Second, the likely causal gene is often located near the most strongly associated variant: in 13 of 21 loci containing a known skeletal growth gene, that gene was closest to the associated variant. Third, at least 19 loci have multiple independently associated variants, suggesting that allelic heterogeneity is a frequent feature of polygenic traits, that comprehensive explorations of already-discovered loci should discover additional variants and that an appreciable fraction of associated loci may have been identified. Fourth, associated variants are enriched for likely functional effects on genes, being over-represented among variants that alter amino-acid structure of proteins and expression levels of nearby genes. Our data explain approximately 10% of the phenotypic variation in height, and we estimate that unidentified common variants of similar effect sizes would increase this figure to approximately 16% of phenotypic variation (approximately 20% of heritable variation). Although additional approaches are needed to dissect the genetic architecture of polygenic human traits fully, our findings indicate that GWA studies can identify large numbers of loci that implicate biologically relevant genes and pathways
Pet problems: Biological and economic factors that influence the release of alien reptiles and amphibians by pet owners
No full textData from: Pet problems: biological and economic factors that influence the release of alien reptiles and amphibians by pet owners
No full text1. The number of alien reptiles and amphibians introduced and established worldwide has been increasing over the last decades. The legal pet trade is the now the dominant pathway by which individuals of these species arrive in their non-native locale. Despite its importance, pet trade pathway specific factors that influence the release (introduction) of exotic reptiles and amphibians have not yet been examined.
2. To address this gap, we set out to identify broad-scale and easily measured biological and economic factors that influence the release of these exotic pets by their owners. We hypothesize that biological factors reflect the cost of care and economic factors reflect the value owners place on their pet, both of which can influence the probability a pet is released. We collected life history and economic data on the 1722 species of reptiles and amphibians sold within the US as pets over the last 18 years. We also compiled a list of pet-trade attributed releases in the US (i.e. all free-living species regardless of whether they successfully established). We then used boosted regression trees to correlate species release status to their life history traits and economic attributes (r2 = 0.51, AUC = 0.89).
3. We found that species with a high probability of being released were imported at higher quantities over our period of record, have a relatively large adult mass, and commanded cheaper retail prices. Quantity imported and price interact with longevity and adult mass to produce non-linear increases in release probability. The most important interaction revealed that large-bodied species imported in high quantities have a three times higher release probability compared to large-bodied species imported in lower quantities.
4. Policy implications. Our results provide much needed guidance toward targeting exotic pet reptile and amphibian species that are at a high risk of being released. In particular, species that are both prevalent in the pet trade and are large-bodied or long-lived have the highest probability of being released. This will aid in developing education and policy solutions aimed at decreasing the rate at which these pets are released, thus curtailing the invasion process before these species can establish and impacts can occu
High annual survival in infected wildlife populations may veil a persistent extinction risk from disease
No full textHost response to emerging pathogens is variable, causing uncertainty about population‐level impacts and challenging effective disease management. White‐nose syndrome (WNS) has caused catastrophic declines in some bat species, while others appear less impacted. Developing predictive models based on observed survival patterns can generate testable hypotheses about mechanisms driving population dynamics and contribute to the development of targeted approaches to disease management. We conducted a mark–recapture study of federally endangered Indiana bats (Myotis sodalis) during 2011–2016. Annual survival decreased from 0.78 (95% CI: 0.59, 0.89) and 0.79 (95% CI: 0.70, 0.86) for females and males, respectively, in 2011 to 0.74 (95% CI: 0.33, 0.94) and 0.75 (95% CI: 0.53, 0.89) for females and males, respectively, in 2015. We then modeled two explanatory mechanisms potentially driving the observed patterns: (1) phased exposure to disease through the spatial spread of the pathogen within the hibernaculum; and (2) cumulative mortality risk from iterative yearly WNS infection. Under a phased exposure scenario, models suggest that infected individuals have an average survival probability of 0.68, and disease prevalence is predicted to reach 100% within 9 yr of disease emergence. Under the cumulative mortality risk hypothesis, survival probability of individuals decreases with each infection cycle. In either case, infected populations are predicted to stabilize at a negative growth rate. Results suggest that Indiana bats tolerate a pathogen load prior to onset of infection, leading to a less pronounced population decline than for other susceptible species. However, the long‐term risk of WNS to Indiana bats may be more severe than current population trends suggest. To inform current conservation management, we performed a vital rate sensitivity analysis, which suggested that modest increases in survival (4–5%) through targeted intervention may return declining populations to stability (λ = 1.0). Demographic modeling approaches coupled with continued population monitoring can highlight important differences in disease response, and ultimately extinction risk, in host species allowing conservation practitioners to tailor intervention actions so that they will be most effective
Scientists' warning to humanity on illegal or unsustainable wildlife trade
No full textIllegal or unsustainable wildlife trade is growing at a global level, threatening the traded species and coexisting biota, and promoting the spread of invasive species. From the loss of ecosystem services to diseases transmitted from wildlife to humans, or connections with major organized crime networks and disruption of local to global economies, its ramifications are pervading our daily lives and perniciously affecting our well-being. Here we build on the manifesto 'World Scientists' Warning to Humanity, issued by the Alliance of World Scientists. As a group of researchers deeply concerned about the consequences of illegal or unsustainable wildlife trade, we review and highlight how these can negatively impact species, ecosystems, and society. We appeal for urgent action to close key knowledge gaps and regulate wildlife trade more stringently.Peer reviewe
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