Managing propagule pressure to prevent invasive species establishments: propagule size, number, and risk‐release curve

2021 ◽  
Author(s):  
Oliver C. Stringham ◽  
Julie L. Lockwood
Keyword(s):  
Invasive Species ◽  
Propagule Pressure ◽  
Propagule Size ◽  
Size Number ◽  
Release Curve

scholarly journals Exotic Reptiles in the Pet Trade: Are They a Threat to New Zealand?

2021 ◽  
Author(s):  
◽  
Kristina Heidy Kikillus
Keyword(s):  
Invasive Species ◽  
New Zealand ◽  
Propagule Pressure ◽  
False Negative ◽  
Local Environment ◽  
Physiological Models ◽  
Thermal Requirements ◽  
Survival Sex ◽  
In Captivity ◽  
Soil Measurements

<p>Worldwide, invasive species are associated with severe ecological and economic impacts. As a group, reptiles are very successful invaders and in some areas where they have established they are responsible for the decline of native fauna and economic disruptions, whilst also posing a threat to human health. Due to its biogeographical isolation and unique evolutionary history, New Zealand is highly susceptible to invasive species. Importation of reptiles into New Zealand is illegal, however over a dozen species of exotic reptile are legally present in captivity and their risk of establishment is unknown. This study investigates their establishment potential and possible impacts by considering 1) the amount of trade and propagule pressure of species, 2) the degree of climate match between their native range and New Zealand, 3) areas that may be suitable for establishment based on physiological models of incubation and development, 4) their ability to transfer pathogens to native fauna and humans, and 5) overall establishment risk. The red-eared slider (Trachemys scripta elegans; RES) is the most common and easily obtained exotic reptile pet in New Zealand, with over 800 sales per annum. The RES is also the species most regularly released into the wild. Climate matching models in this study were developed to minimise false-negative predictions, to generate a suitability score irrespective of the prevalence of species records (allowing species to be easily compared to one another), and incorporated a weighted multimodel average prediction based on the relative importance of climatic variables to each species. These correlative models indicated that the blotched blue-tongue skink (Tiliqua nigrolutea) had the highest degree of climate match with parts of New Zealand, while the common blue-tongue skink (T. scincoides) had the highest proportion of land area predicted to be suitable for establishment. The other 10 species generally had both low climate match scores and limited areas within New Zealand predicted to be suitable. Mechanistic models focus upon environmental influences on physiological processes of a species, such as development and growth. Degree-day models, combined with soil measurements in potential reptile nesting sites in New Zealand, were utilised to determine if environmental conditions were suitable for the successful reproduction of oviparous exotic reptiles. These models predicted that the New Zealand environment meets the minimum thermal requirements for the incubation of eggs of RES, snake-neck turtles (Chelodina longicollis), and Reeves turtles (Chinemys reevesii). While prevalence of Salmonella in exotic reptiles is higher than that of native reptiles, it is considerably lower than that of exotic reptiles overseas. All serovars identified in this study had been previously reported both in humans and reptiles in New Zealand. The overall risk assessment for 12 species of exotic reptile kept in captivity in New Zealand indicates that blotched blue-tongue skinks and RES pose the highest establishment risk. Blotched blue-tongue skinks are allegedly only present in zoos. Therefore, based on propagule pressure, RES pose the highest establishment risk and efforts should focus on minimising release events and removing feral individuals from the New Zealand environment. In summary, at least eight species of exotic reptile legally traded within New Zealand are predicted to be capable of surviving in a portion of the New Zealand environment and at least three species have the potential to successfully breed in warmer microclimates. However, further research involving climatic tolerances and breeding potential (i.e., soil moisture content, juvenile survival, sex ratio, and predicted climate change) is recommended. Public education and possible regulations imposed on the New Zealand exotic reptile trade may prevent introductions of these species into the local environment and still allow selected species to be enjoyed by the New Zealand public. The methods developed in this study may be easily applied to other species and other geographic regions, allowing investigation into the establishment risk of alien species. This may help guide control and management efforts and help stem the tide of the growing problem of invasive species.</p>

scholarly journals Are Introduced Alien Species More Predisposed to Invasion in Recipient Environments If They Provide a Wider Range of Services to Humans?

Diversity ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 553
Author(s):  
Kowiyou Yessoufou ◽  
Annie Estelle Ambani
Keyword(s):  
South Africa ◽  
Invasive Species ◽  
Alien Species ◽  
Propagule Pressure ◽  
Phylogenetic Signal ◽  
Dna Barcode ◽  
Alien Plants ◽  
Invasion Success ◽  
Alien Invasive Species ◽  
Unexpected Finding

The drivers of invasion success of alien species remain, to some extent, a matter of debate. Here, we suggest that the services (the benefits humans obtain from a species) provided by alien plants could predict their invasion status, such that alien species providing more services would be more likely to be invasive than not. The rationale for this expectation is that alien species providing multiple services stand a better chance of being introduced in various numbers and multiple times outside their native range (propagule pressure theory). We investigated this hypothesis on alien woody species in South Africa. First, we defined 12 services provided by all the 210 known naturalized alien woody plants in South Africa. Then, we tested for a phylogenetic signal in these services using a DNA barcode-based phylogeny. Finally, we tested for potential links between the services and invasion status by fitting GLM models with appropriate error families. We found a phylogenetic signal in most services, suggesting that closely related species tend to provide similar services. Counter-intuitively, we consistently found that alien non-invasive species tend to provide more services, or even unique services, in comparison to alien invasive species. Although alternative scenarios are plausible to explain this unexpected finding, we speculate that harvesting alien plants for human benefits may limit their invasion ability. This warrants further investigation.

scholarly journals Timing between successive introduction events determines establishment success in bacteria with an Allee effect

2019 ◽  
Vol 286 (1902) ◽  
pp. 20190598 ◽  
Author(s):  
Michael D. Dressler ◽  
Josue Conde ◽  
Omar Tonsi Eldakar ◽  
Robert P. Smith
Keyword(s):  
Infectious Disease ◽  
Allee Effect ◽  
Propagule Pressure ◽  
Temporal Distribution ◽  
Invasion Biology ◽  
Theoretical Studies ◽  
Establishment Success ◽  
Propagule Size ◽  
Population Establishment ◽  
Principal Parts

Propagule pressure is a leading determinant of population establishment. Yet, an experimental understanding of how propagule size and number (two principal parts of propagule pressure) determine establishment success remains incomplete. Theoretical studies suggest that the timing between introduction events, a component of propagule number, can influence establishment success. However, this dynamic has rarely been explored experimentally. Using Escherichia coli engineered with an Allee effect, we investigated how the timing of two introduction events influences establishment. For populations introduced below the Allee threshold, establishment occurred if the time between two introduction events was sufficiently short, with the length of time between events further reduced by reducing growth rate. Interestingly, we observed that as the density of bacteria introduced in one introduction event increased, the time between introduction events that allowed for establishment increased. Using a mathematical model, we provide support that the mechanism behind these trends is the ability of the first population to modify the environment, which can pave the way for establishment of the second population. Our results provide experimental evidence that the temporal distribution of introduction events regulates establishment, furthering our understanding of propagule pressure and may have implications in invasion biology and infectious disease.

scholarly journals Quantifying the propagule load associated with the construction of an Antarctic research station

2009 ◽  
Vol 21 (5) ◽  
pp. 471-475 ◽  
Author(s):  
Jennifer E. Lee ◽  
Steven L. Chown
Keyword(s):  
Invasive Species ◽  
Biological Invasions ◽  
Quantitative Assessment ◽  
Propagule Pressure ◽  
Research Effort ◽  
Research Station ◽  
Antarctic Research

AbstractAlthough the impacts of biological invasions are widely appreciated, a bias exists in research effort to post dispersal processes because of the difficulties of measuring propagule pressure. Here we quantify the propagule pressure associated with the construction of a research station in Antarctica. Based on quantitative assessment of different classes of cargo, we predict that over 5000 seeds will be entrained during the period of building the station. Seeds from 34 taxa were identified, including known invasive species.

scholarly journals Propagule pressure and the establishment of emergent polyploid populations

2020 ◽  
Vol 127 (1) ◽  
pp. 1-5
Author(s):  
Donald A Levin
Keyword(s):  
Invasive Species ◽  
Seed Production ◽  
Propagule Pressure ◽  
Prime Factor ◽  
Demographic Stochasticity ◽  
Local Populations ◽  
Population Survival ◽  
Successful Colonization ◽  
Number Of Seeds ◽  
Diploid Populations

Abstract Background Whereas the incidence or rate of polyploid speciation in flowering plants is modest, the production of polyploid individuals within local populations is widespread. Explanations for this disparity primarily have focused on properties or interactions of polyploids that limit their persistence. Hypothesis The emergence of local polyploid populations within diploid populations is similar to the arrival of invasive species at new, suitable sites, with the exception that polyploids suffer interference from their progenitor(s). The most consistent predictor of successful colonization by invasive plants is propagule pressure, i.e. the number of seeds introduced. Therefore, insufficient propagule pressure, i.e. the formation of polyploid seeds within diploid populations, ostensibly is a prime factor limiting the establishment of newly emergent polyploids within local populations. Increasing propagule number reduces the effects of genetic, environmental and demographic stochasticity, which thwart population survival. As with invasive species, insufficient seed production within polyploid populations limits seed export, and thus reduces the chance of polyploid expansion. Conclusion The extent to which propagule pressure limits the establishment of local polyploid populations remains to be determined, because we know so little. The numbers of auto- or allopolyploid seed in diploid populations rarely have been ascertained, as have the numbers of newly emergent polyploid plants within diploid populations. Moreover, seed production by these polyploids has yet to be assessed.

Medawar?s medicine: the local-global prescription for conservation actions

2008 ◽  
Vol 14 (2) ◽  
pp. 89
Author(s):  
Robert A. Leidy ◽  
Peggy Lee Fiedler
Keyword(s):  
Invasive Species ◽  
Habitat Fragmentation ◽  
Pacific Islands ◽  
Current Knowledge ◽  
Natural Habitat ◽  
Conservation Science ◽  
Conservation Practice ◽  
Size Number ◽  
Conservation Actions ◽  
Effective Conservation

Duffy and Kraus (2008) provide a broadly relevant and generally insightful overview of what plagues implementation of effective conservation science. That their overview is true is largely because many, if not all, of their insights and proffered solutions to remedy the ineffectiveness of conservation science apply globally. That is, one could replace ?Hawai?i? with any number of other Pacific islands and continental venues, a depressing and rapidly growing list of threatened ecosystems. In essence, the conservation issues raised by Duffy and Kraus are not local, regional, or by any means, unique to Hawai?i, although Hawai?i does represent one of the more challenging places to implement conservation practice successfully. Distinctions between regional (viz., island) and continental environmental crises are becoming blurred as ecosystems become increasingly fragmented and isolated, and their supporting processes altered. For example, California at approximately 40.5 million hectares, 38 million residents, and 150 years of habitat fragmentation now consists of many much smaller natural habitat fragments surrounded by a matrix of human-altered landscapes than only 50 years ago. These island fragments vary in size, number and spatial orientation not unlike island archipelagos. Furthermore, current knowledge gaps are universal, invasive species are invading every island and continent, more species are endangered or extinct than we can possibly know, document or protect, millions of ecosystems worldwide would benefit from some type of protection, active restoration, and management, and all types of conservation activities are grossly under funded around the globe.

scholarly journals Propagule size and dispersal costs mediate establishment success of an invasive species

Ecology ◽  
2016 ◽  
Vol 97 (3) ◽  
pp. 569-575 ◽  
Author(s):  
Rolanda Lange ◽  
Dustin J. Marshall
Keyword(s):  
Invasive Species ◽  
Establishment Success ◽  
Propagule Size
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