1
|
Howell E, White A, Lurz PWW, Boots M. Immune interactions and heterogeneity in transmission drives the pathogen-mediated invasion of grey squirrels in the UK. J Anim Ecol 2024; 93:663-675. [PMID: 38494654 DOI: 10.1111/1365-2656.14074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 02/06/2024] [Indexed: 03/19/2024]
Abstract
Mathematical models highlighted the importance of pathogen-mediated invasion, with the replacement of red squirrels by squirrelpox virus (SQPV) carrying grey squirrels in the UK, a well-known example. In this study, we combine new epidemiological models, with a range of infection characteristics, with recent longitudinal field and experimental studies on the SQPV dynamics in red and grey squirrel populations to better infer the mechanistic basis of the disease interaction. A key finding is that a model with either partial immunity or waning immunity and reinfection, where individuals become seropositive on the second exposure to infection, that up to now has been shown in experimental data only, can capture the key aspects of the field study observations. By fitting to SQPV epidemic observations in isolated red squirrel populations, we can infer that SQPV transmission between red squirrels is significantly (4×) higher than the transmission between grey squirrels and as a result our model shows that disease-mediated replacement of red squirrels by greys is considerably more rapid than replacement in the absence of SQPV. Our findings recover the key results of the previous model studies, which highlights the value of simple strategic models that are appropriate when there are limited data, but also emphasise the likely complexity of immune interactions in wildlife disease and how models can help infer disease processes from field data.
Collapse
Affiliation(s)
- E Howell
- Department of Mathematics and the Maxwell Institute for Mathematical Sciences, Heriot-Watt University, Edinburgh, UK
| | - A White
- Department of Mathematics and the Maxwell Institute for Mathematical Sciences, Heriot-Watt University, Edinburgh, UK
| | - P W W Lurz
- The Royal (Dick) School of Veterinary Studies and the Roslin Institute, University of Edinburgh, Roslin, UK
| | - M Boots
- Department of Integrative Biology, University of California, Berkeley, California, USA
- Centre for Ecology and Conservation, Biosciences, University of Exeter, Cornwall, UK
| |
Collapse
|
2
|
Hughes EH, Moyers-Gonzalez M, Murray R, Wilson PL. Partial differential equation models for invasive species spread in the presence of spatial heterogeneity. PLoS One 2024; 19:e0300968. [PMID: 38564572 PMCID: PMC10986974 DOI: 10.1371/journal.pone.0300968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 03/06/2024] [Indexed: 04/04/2024] Open
Abstract
Models of invasive species spread often assume that landscapes are spatially homogeneous; thus simplifying analysis but potentially reducing accuracy. We extend a recently developed partial differential equation model for invasive conifer spread to account for spatial heterogeneity in parameter values and introduce a method to obtain key outputs (e.g. spread rates) from computational simulations. Simulations produce patterns of spatial spread which appear qualitatively similar to observed patterns in grassland ecosystems invaded by exotic conifers, validating our spatially explicit strategy. We find that incorporating spatial variation in different parameters does not significantly affect the evolution of invasions (which are characterised by a long quiescent period followed by rapid evolution towards to a constant rate of invasion) but that distributional assumptions can have a significant impact on the spread rate of invasions. Our work demonstrates that spatial variation in site-suitability or other parameters can have a significant impact on invasions and must be considered when designing models of invasive species spread.
Collapse
Affiliation(s)
- Elliott H. Hughes
- School of Mathematics and Statistics, University of Canterbury, Christchurch, New Zealand
- Mathematical Institute, University of Oxford, Oxford, United Kingdom
| | - Miguel Moyers-Gonzalez
- School of Mathematics and Statistics, University of Canterbury, Christchurch, New Zealand
| | - Rua Murray
- School of Mathematics and Statistics, University of Canterbury, Christchurch, New Zealand
| | - Phillip L. Wilson
- School of Mathematics and Statistics, University of Canterbury, Christchurch, New Zealand
- Te Pūnaha Matatini Centre of Research Excellence, University of Auckland, Auckland, New Zealand
| |
Collapse
|
3
|
Rivera-Estay V, Córdova-Lepe F, Moreno-Gómez FN, Benitez H, Gutiérrez R. Exploring the effects of competition and predation on the success of biological invasion through mathematical modeling. Sci Rep 2024; 14:4416. [PMID: 38388475 PMCID: PMC10883959 DOI: 10.1038/s41598-024-53344-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Accepted: 01/31/2024] [Indexed: 02/24/2024] Open
Abstract
Biological invasions are a major cause of species extinction and biodiversity loss. Exotic predators are the type of introduced species that have the greatest negative impact, causing the extinction of hundreds of native species. Despite this, they continue to be intentionally introduced by humans. Understanding the causes that determine the success of these invasions is a challenge within the field of invasion biology. Mathematical models play a crucial role in understanding and predicting the behavior of exotic species in different ecosystems. This study examines the effect of predation and competition on the invasion success of an exotic generalist predator in a native predator-prey system. Considering that the exotic predator both consumes the native prey and competes with the native predator, it is necessary to study the interplay between predation and competition, as one of these interspecific interactions may either counteract or contribute to the impact of the other on the success of a biological invasion. Through a mathematical model, represented by a system of ordinary differential equations, it is possible to describe four different scenarios upon the arrival of the exotic predator in a native predator-prey system. The conditions for each of these scenarios are described analytically and numerically. The numerical simulations are performed considering the American mink (Mustela vison), an invasive generalist predator. The results highlight the importance of considering the interplay between interspecific interactions for understanding biological invasion success.
Collapse
Affiliation(s)
- Viviana Rivera-Estay
- Doctorado en Modelamiento Matemático Aplicado, Facultad de Ciencias Básicas, Universidad Católica del Maule, 3466706, Talca, Chile.
| | - Fernando Córdova-Lepe
- Departamento de Matemática, Física y Estadística, Facultad de Ciencias Básicas, Universidad Católica del Maule, 3466706, Talca, Chile
| | - Felipe N Moreno-Gómez
- Departamento de Biología y Química, Facultad de Ciencias Básicas, Universidad Católica del Maule, 3466706, Talca, Chile
| | - Hugo Benitez
- Laboratorio de Ecología y Morfometría Evolutiva, Centro de Investigación de Estudios Avanzados del Maule, Instituto Milenio Biodiversidad de Ecosistemas Antárticos y Subantárticos (BASE), Universidad Católica del Maule, 3466706, Talca, Chile
- Centro de Investigación en Recursos Naturales y Sustentabilidad (CIRENYS), Universidad Bernardo O'Higgins, Avenida Viel 1497, 8370993, Santiago, Chile
| | - Rodrigo Gutiérrez
- Departamento de Matemática, Física y Estadística, Facultad de Ciencias Básicas, Universidad Católica del Maule, 3466706, Talca, Chile
| |
Collapse
|
4
|
James A, Hann A, Holland EP. Brood size in an uncertain world. ROYAL SOCIETY OPEN SCIENCE 2023; 10:221362. [PMID: 37351496 PMCID: PMC10282570 DOI: 10.1098/rsos.221362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 06/08/2023] [Indexed: 06/24/2023]
Abstract
Reproduction in an uncertain world is fraught. The consequences of investing in too many offspring in a resource poor season can be disastrous but so too is missing the opportunity of a resource rich year. We consider a simple population and individual growth model and use Lyapunov exponents to find analytical results for the optimum brood size under stochastic environmental conditions. We show that if the environment shows dramatic changes between breeding seasons choosing a smaller brood size is more likely to be successful but the best strategy is to synchronize your reproduction to the food availability. Finally, we show that if the cost of having offspring is high it can be better to live in a highly varying world with a plastic strategy that synchronizes to the environment than to live in a deterministic world with a constant strategy, a finding with implications for invasive species and climate change.
Collapse
Affiliation(s)
- Alex James
- School of Maths and Stats, University of Canterbury, Christchurch, New Zealand
| | - Alexander Hann
- School of Maths and Stats, University of Canterbury, Christchurch, New Zealand
| | | |
Collapse
|
5
|
Wauters LA, Lurz PWW, Santicchia F, Romeo C, Ferrari N, Martinoli A, Gurnell J. Interactions between native and invasive species: A systematic review of the red squirrel-gray squirrel paradigm. Front Ecol Evol 2023. [DOI: 10.3389/fevo.2023.1083008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023] Open
Abstract
The eastern gray squirrel (Sciurus carolinensis) has been labeled as one of the 100 worst invasive alien species by the IUCN. In Europe, the species has been introduced to Britain, Ireland and Italy, and its subsequent spread has resulted in wide-scale extinction of native Eurasian red squirrels (Sciurus vulgaris) from the areas colonized by the gray squirrel. This replacement of a native by an alien competitor is one of the best documented cases of the devastating effects of biological invasions on native fauna. To understand how this replacement occurs, we present a systematic review of the literature on competition and interactions between red and gray squirrels. We describe the patterns of red and gray squirrel distribution in those parts of Europe where gray squirrels occur and summarize the evidence on the different processes and mechanisms determining the outcome of competition between the native and alien species including the influence of predators and pathogens. Some of the drivers behind the demise of the red squirrel have been intensively studied and documented in the past 30 years, but recent field studies and mathematical models revealed that the mechanisms underlying the red-gray paradigm are more complex than previously thought and affected by landscape-level processes. Therefore, we consider habitat type and multi-species interactions, including host-parasite and predator-prey relationships, to determine the outcome of the interaction between the two species and to better address gray squirrel control efforts.
Collapse
|
6
|
Slade A, White A, Lurz PW, Shuttleworth C, Tosh DG, Twining JP. Indirect effects of pine marten recovery result in benefits to native prey through suppression of an invasive species and a shared pathogen. Ecol Modell 2023. [DOI: 10.1016/j.ecolmodel.2022.110216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
|
7
|
Slade A, White A, Lurz PWW, Shuttleworth C, Lambin X. A temporal refuge from predation can change the outcome of prey species competition. OIKOS 2022. [DOI: 10.1111/oik.08565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andrew Slade
- Maxwell Inst. for Mathematical Sciences, Dept of Mathematics, Heriot‐Watt Univ. Edinburgh UK
| | - Andy White
- Maxwell Inst. for Mathematical Sciences, Dept of Mathematics, Heriot‐Watt Univ. Edinburgh UK
| | - Peter W. W. Lurz
- Royal (Dick) School of Veterinary Studies, Univ. of Edinburgh Midlothian UK
| | | | - Xavier Lambin
- School of Biological Sciences, Univ. of Aberdeen Aberdeen UK
| |
Collapse
|
8
|
Shuttleworth CM, Everest D, Holmes P, Bell S, Cripps R. An Opportunistic Assessment of the Impact of Squirrelpox Disease Outbreaks upon a Red Squirrel Population Sympatric with Grey Squirrels in Wales. Animals (Basel) 2022; 12:ani12010099. [PMID: 35011205 PMCID: PMC8749610 DOI: 10.3390/ani12010099] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 12/27/2021] [Accepted: 12/29/2021] [Indexed: 11/16/2022] Open
Abstract
Simple Summary In Europe, squirrelpox virus is carried by non-native grey squirrels and spread into native red squirrel populations. The virus causes a large proportion of infected red squirrels to die and contributes to local declines and the replacement by grey squirrels. There are relatively few published studies quantifying the impact of disease amongst red squirrels. We present findings from a short-term study in north Wales, United Kingdom. Abstract Native red squirrels (Sciurus vulgaris) persisted in the coastal mainland woodlands of northern Gwynedd whilst sympatric with an invasive grey squirrel (Sciurus carolinensis) population suppressed by culling. Squirrelpox disease in the red squirrel population was recorded in 2017 and 2020/21. An autumn 2020 outbreak was associated with only 17.4% of animals caught and marked in the preceding June known to be present in March 2021. Despite an opportunistic data collection lacking the rigour of empirical experimental design, we observed low local survival rates similar to previously published accounts reported during major squirrelpox outbreaks. The use of a conservation dog to detect red squirrel carcasses resulted in positive detection and confirmation of a temporal and spatial expansion of one disease outbreak. The study is the first in Wales to use conservation dogs and the findings reinforce the vital strategic importance of geographical isolation reducing sympatry of red with grey squirrels in European regions where the introduced congener is a source of the squirrelpox infection.
Collapse
Affiliation(s)
| | | | - Paul Holmes
- APHA Shrewsbury, Veterinary Investigation Centre, Shrewsbury SY1 4HD, UK; (P.H.); (S.B.)
| | - Suzi Bell
- APHA Shrewsbury, Veterinary Investigation Centre, Shrewsbury SY1 4HD, UK; (P.H.); (S.B.)
| | - Rachel Cripps
- Lancashire Wildlife Trust, Bamber Bridge PR5 6BY, UK;
| |
Collapse
|
9
|
Roberts MG, Heesterbeek JAP. Infection dynamics in ecosystems: on the interaction between red and grey squirrels, pox virus, pine martens and trees. J R Soc Interface 2021; 18:20210551. [PMID: 34637641 PMCID: PMC8513127 DOI: 10.1098/rsif.2021.0551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Ecological and epidemiological processes and interactions influence each other, positively and negatively, directly and indirectly. The invasion potential of pathogens is influenced by the ecosystem context of their host species' populations. This extends to the capacity of (multiple) host species to maintain their (common) pathogen and the way pathogen dynamics are influenced by changes in ecosystem composition. This paper exemplifies these interactions and consequences in a study of red and grey squirrel dynamics in the UK. Differences and changes in background habitat and trophic levels above and below the squirrel species lead to different dynamic behaviour in many subtle ways. The range of outcomes of the different interactions shows that one has to be careful when drawing conclusions about the mechanisms and processes involved in explaining observed phenomena concerning pathogens in their natural environment. The dynamic behaviour also shows that planning interventions, for example for conservation purposes, benefits from understanding the complexity of interactions beyond the particular pathogen and its threatened host species.
Collapse
Affiliation(s)
- M G Roberts
- School of Natural and Computational Sciences, New Zealand Institute for Advanced Study and the Infectious Disease Research Centre, Massey University, Private Bag 102 904, North Shore Mail Centre, Auckland, New Zealand
| | - J A P Heesterbeek
- Department of Population Health Sciences, Faculty of Veterinary Medicine, University of Utrecht, Yalelaan 7, Utrecht 3584 CL, The Netherlands
| |
Collapse
|
10
|
Goetz SM, Hileman ET, Nafus MG, Yackel Adams AA, Bryant AR, Reed RN, Siers SR. Brown Treesnake Mortality After Aerial Application of Toxic Baits. J Wildl Manage 2021. [DOI: 10.1002/jwmg.22108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Scott M. Goetz
- U.S. Department of Agriculture, Wildlife Services, National Wildlife Research Center 233 Pangelinan Way Barrigada GU 96913 USA
| | - Eric T. Hileman
- U.S. Geological Survey, Fort Collins Science Center 2150 Centre Avenue, Building C Fort Collins CO 80526 USA
| | - Melia G. Nafus
- U.S. Geological Survey, Fort Collins Science Center 2150 Centre Avenue, Building C Fort Collins CO 80526 USA
| | - Amy A. Yackel Adams
- U.S. Geological Survey, Fort Collins Science Center 2150 Centre Avenue, Building C Fort Collins CO 80526 USA
| | - Amanda R. Bryant
- Cherokee Nation Technologies, U.S. Geological Survey Brown Treesnake Project Yigo GU 96929 USA
| | - Robert N. Reed
- U.S. Geological Survey, Fort Collins Science Center 2150 Centre Avenue, Building C Fort Collins CO 80526 USA
| | - Shane R. Siers
- U.S. Department of Agriculture, Wildlife Services, National Wildlife Research Center 233 Pangelinan Way Barrigada GU 96913 USA
| |
Collapse
|
11
|
Slade A, White A, Kortland K, Lurz PWW. Natural strongholds for red squirrel conservation in Scotland. NATURE CONSERVATION 2021. [DOI: 10.3897/natureconservation.43.62864] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The Eurasian Red Squirrel (Sciurus vulgaris) is under threat from the invasive North American eastern Grey Squirrel (Sciurus carolinensis) with 80% of the remaining red squirrel populations in the British Isles found in Scotland. In this study we develop a spatially explicit mathematical model of the red and grey squirrel system and use it to assess the population viability of red squirrels across Scotland. In particular, we aim to identify existing forests – natural strongholds for red squirrels – that can successfully support red squirrels under UK Forestry Standard management and protect them from potential disease-mediated competition from grey squirrels. Our model results indicate that if current levels of grey squirrel control, which restrict or reduce the distribution of grey squirrels, are continued then there will be large expanses of forests in northern Scotland that support viable red squirrel populations. Model results that represent (hypothetical) scenarios where grey squirrel control no longer occurred indicated that grey squirrel range expansion and the process of red squirrel replacement would be slow. Model results for an assumed worst-case scenario where grey squirrels have expanded to all regions in Scotland identified forest regions – denoted natural strongholds – that could currently support red squirrels under UK Forestry Standard management practice. The results will be used to inform forest management policy and support a strategic review of red squirrel management by land management agencies and other stakeholders.
Collapse
|
12
|
Shuttleworth CM, Brady D, Cross P, Gardner L, Greenwood A, Jackson N, McKinney C, Robinson N, Trotter S, Valle S, Wood K, Hayward MW. Recalibrating risk: Implications of squirrelpox virus for successful red squirrel translocations within mainland
UK. CONSERVATION SCIENCE AND PRACTICE 2021. [DOI: 10.1111/csp2.321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Affiliation(s)
| | | | - Paul Cross
- School of Natural Sciences, College Road, Bangor University Gwynedd Wales UK
| | | | - Andrew Greenwood
- Wildlife Vets International, Station House Keighley West Yorkshire UK
| | - Nick Jackson
- National Zoological Society of Wales Colwyn Bay, Conwy UK
| | | | - Nikki Robinson
- The Wildlife Trusts, The Kiln, Waterside Newark, Nottinghamshire UK
| | | | - Simon Valle
- School of Natural Sciences, College Road, Bangor University Gwynedd Wales UK
| | - Kim Wood
- National Zoological Society of Wales Colwyn Bay, Conwy UK
| | - Matt W. Hayward
- School of Environmental and Life Sciences, University of Newcastle Callaghan New South Wales Australia
- Centre for African Conservation Ecology, Nelson Mandela University Port Elizabeth South Africa
| |
Collapse
|
13
|
Pepper N, Gerardo-Giorda L, Montomoli F. Meta-modeling on detailed geography for accurate prediction of invasive alien species dispersal. Sci Rep 2019; 9:16237. [PMID: 31700073 PMCID: PMC6838098 DOI: 10.1038/s41598-019-52763-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Accepted: 10/22/2019] [Indexed: 11/09/2022] Open
Abstract
Invasive species are recognized as a significant threat to biodiversity. The mathematical modeling of their spatio-temporal dynamics can provide significant help to environmental managers in devising suitable control strategies. Several mathematical approaches have been proposed in recent decades to efficiently model the dispersal of invasive species. Relying on the assumption that the dispersal of an individual is random, but the density of individuals at the scale of the population can be considered smooth, reaction-diffusion models are a good trade-off between model complexity and flexibility for use in different situations. In this paper we present a continuous reaction-diffusion model coupled with arbitrary Polynomial Chaos (aPC) to assess the impact of uncertainties in the model parameters. We show how the finite elements framework is well-suited to handle important landscape heterogeneities as elevation and the complex geometries associated with the boundaries of an actual geographical region. We demonstrate the main capabilities of the proposed coupled model by assessing the uncertainties in the invasion of an alien species invading the Basque Country region in Northern Spain.
Collapse
Affiliation(s)
- Nick Pepper
- UQLab, Department of Aeronautics, Imperial College London, SW7 2AZ, London, UK.
| | | | - Francesco Montomoli
- UQLab, Department of Aeronautics, Imperial College London, SW7 2AZ, London, UK
| |
Collapse
|
14
|
de Ávila-Simas S, Morato MM, Reynalte-Tataje DA, Silveira HB, Zaniboni-Filho E, E. Normey-Rico J. Model-based predictive control for the regulation of the golden mussel Limnoperna fortunei (Dunker, 1857). Ecol Modell 2019. [DOI: 10.1016/j.ecolmodel.2019.05.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|