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Sutherland WJ, Bennett C, Brotherton PNM, Butterworth HM, Clout MN, Côté IM, Dinsdale J, Esmail N, Fleishman E, Gaston KJ, Herbert-Read JE, Hughes A, Kaartokallio H, Le Roux X, Lickorish FA, Matcham W, Noor N, Palardy JE, Pearce-Higgins JW, Peck LS, Pettorelli N, Pretty J, Scobey R, Spalding MD, Tonneijck FH, Tubbs N, Watson JEM, Wentworth JE, Wilson JD, Thornton A. A global biological conservation horizon scan of issues for 2023. Trends Ecol Evol 2023; 38:96-107. [PMID: 36460563 DOI: 10.1016/j.tree.2022.10.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 10/24/2022] [Accepted: 10/25/2022] [Indexed: 12/03/2022]
Abstract
We present the results of our 14th horizon scan of issues we expect to influence biological conservation in the future. From an initial set of 102 topics, our global panel of 30 scientists and practitioners identified 15 issues we consider most urgent for societies worldwide to address. Issues are novel within biological conservation or represent a substantial positive or negative step change at global or regional scales. Issues such as submerged artificial light fisheries and accelerating upper ocean currents could have profound negative impacts on marine or coastal ecosystems. We also identified potentially positive technological advances, including energy production and storage, improved fertilisation methods, and expansion of biodegradable materials. If effectively managed, these technologies could realise future benefits for biological diversity.
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Affiliation(s)
- William J Sutherland
- Conservation Science Group, Department of Zoology, Cambridge University, The David Attenborough Building, Pembroke Street, Cambridge CB2 3QZ, UK; Biosecurity Research Initiative at St Catharine's (BioRISC), St Catharine's College, University of Cambridge, Cambridge, UK.
| | - Craig Bennett
- Royal Society of Wildlife Trusts, The Kiln, Waterside, Mather Road, Newark, Nottinghamshire NG24 1WT, UK
| | - Peter N M Brotherton
- Natural England, 4th Floor Foss House, Kings Pool, 1-2 Peasholme Green, York YO1 7PX, UK
| | - Holly M Butterworth
- Natural Resources Wales, Cambria House, 29 Newport Road, Cardiff CF24 0TP, UK
| | - Mick N Clout
- Centre for Biodiversity and Biosecurity, School of Biological Sciences, University of Auckland, PB 92019, Auckland, New Zealand
| | - Isabelle M Côté
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Jason Dinsdale
- Environment Agency, Horizon House, Deanery Road, Bristol BS1 5AH, UK
| | - Nafeesa Esmail
- Wilder Institute/Calgary Zoo, 1300 Zoo Road NE, Calgary, AB T2E 7V6, Canada
| | - Erica Fleishman
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Kevin J Gaston
- Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall TR10 9FE, UK
| | | | - Alice Hughes
- School of Biological Sciences, University of Hong Kong, Pok Fu Lam, Hong Kong
| | | | - Xavier Le Roux
- University of Lyon, Microbial Ecology Centre, INRAE (UMR1418), CNRS (UMR5557), University Lyon 1, 69622 Villeurbanne, France
| | - Fiona A Lickorish
- UK Research and Consultancy Services (RCS) Ltd, Valletts Cottage, Westhope, Hereford HR4 8BU, UK
| | - Wendy Matcham
- Natural Environment Research Council, UK Research and Innovation, Polaris House, North Star Avenue, Swindon SN2 1FL, UK
| | - Noor Noor
- UN Environment Programme World Conservation Monitoring Centre (UNEP-WCMC), 219 Huntingdon Road, Cambridge CB3 0DL, UK
| | - James E Palardy
- The Pew Charitable Trusts, 901 E St. NW, Washington, DC 20004, USA
| | - James W Pearce-Higgins
- Conservation Science Group, Department of Zoology, Cambridge University, The David Attenborough Building, Pembroke Street, Cambridge CB2 3QZ, UK; British Trust for Ornithology, The Nunnery, Thetford, Norfolk IP24 2PU, UK
| | - Lloyd S Peck
- British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, UK
| | - Nathalie Pettorelli
- Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK
| | - Jules Pretty
- Centre for Public and Policy Engagement and School of Life Sciences, University of Essex, Colchester CO4 3SQ, UK
| | - Richard Scobey
- TRAFFIC, The David Attenborough Building, Pembroke Street, Cambridge CB2 3QZ, UK
| | - Mark D Spalding
- Conservation Science Group, Department of Zoology, Cambridge University, The David Attenborough Building, Pembroke Street, Cambridge CB2 3QZ, UK; The Nature Conservancy, Strade delle Tolfe, 14, Siena 53100, Italy
| | | | - Nicolas Tubbs
- WWF-Belgium, BD Emile Jacqumainlaan 90, 1000 Brussels, Belgium
| | - James E M Watson
- School of Earth and Environmental Sciences, University of Queensland, St Lucia, QLD 4072, Australia
| | - Jonathan E Wentworth
- Parliamentary Office of Science and Technology, 14 Tothill Street, Westminster, London SW1H 9NB, UK
| | - Jeremy D Wilson
- RSPB Centre for Conservation Science, 2 Lochside View, Edinburgh EH12 9DH, UK
| | - Ann Thornton
- Conservation Science Group, Department of Zoology, Cambridge University, The David Attenborough Building, Pembroke Street, Cambridge CB2 3QZ, UK
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Garvey PM, Glen AS, Clout MN, Nichols M, Pech RP. Niche partitioning in a guild of invasive mammalian predators. Ecol Appl 2022; 32:e2566. [PMID: 35138656 PMCID: PMC9285952 DOI: 10.1002/eap.2566] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 08/24/2021] [Accepted: 09/15/2021] [Indexed: 05/28/2023]
Abstract
Predators compete aggressively for resources, establishing trophic hierarchies that influence ecosystem structure. Competitive interactions are particularly important in invaded ecosystems where introduced predators can suppress native prey species. We investigated whether niche partitioning exists within a guild of invasive mammalian predators and determined the consequences for native species. Over 4405 camera-trap days, we assessed interactions among three invasive predators: two apex predators (feral cats Felis catus and ferrets Mustela furo) and a mesopredator (stoats Mustela erminea), in relation to their primary prey (lagomorphs, rodents and birds) and habitat use. Further, we tested for mesopredator release by selectively removing cats and ferrets in a pulse perturbation experiment. We found compelling evidence of niche partitioning; spatiotemporal activity of apex predators maximized access to abundant invasive prey, with ferrets targeting lagomorphs and cats targeting rodents. Mesopredators adjusted their behavior to reduce the risk of interference competition, thereby restricting access to abundant prey but increasing predation pressure on diurnal native birds. Stoats were only recorded at the treatment site after both larger predators were removed, becoming the most frequently detected predator at 6 months post-perturbation. We suggest there is spatial and resource partitioning within the invasive predator guild, but that this is incomplete, and avoidance is achieved by temporal partitioning within overlapping areas. Niche partitioning among invasive predators facilitates coexistence, but simultaneously intensifies predation pressure on vulnerable native species.
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Affiliation(s)
| | | | - Mick N. Clout
- Centre for Biodiversity and Biosecurity, School of Biological SciencesUniversity of AucklandAucklandNew Zealand
| | - Margaret Nichols
- Centre for Wildlife Management and ConservationLincoln UniversityCanterburyNew Zealand
| | - Roger P. Pech
- Manaaki Whenua – Landcare ResearchLincolnNew Zealand
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Garvey PM, Glen AS, Clout MN, Wyse SV, Nichols M, Pech RP. Exploiting interspecific olfactory communication to monitor predators. Ecol Appl 2017; 27:389-402. [PMID: 27983773 DOI: 10.1002/eap.1483] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 09/11/2016] [Accepted: 11/08/2016] [Indexed: 06/06/2023]
Abstract
Olfaction is the primary sense of many mammals and subordinate predators use this sense to detect dominant species, thereby reducing the risk of an encounter and facilitating coexistence. Chemical signals can act as repellents or attractants and may therefore have applications for wildlife management. We devised a field experiment to investigate whether dominant predator (ferret Mustela furo) body odor would alter the behavior of three common mesopredators: stoats (Mustela erminea), hedgehogs (Erinaceus europaeus), and ship rats (Rattus rattus). We predicted that apex predator odor would lead to increased detections, and our results support this hypothesis as predator kairomones (interspecific olfactory messages that benefit the receiver) provoked "eavesdropping" behavior by mesopredators. Stoats exhibited the most pronounced responses, with kairomones significantly increasing the number of observations and the time spent at a site, so that their occupancy estimates changed from rare to widespread. Behavioral responses to predator odors can therefore be exploited for conservation and this avenue of research has not yet been extensively explored. A long-life lure derived from apex predator kairomones could have practical value, especially when there are plentiful resources that reduce the efficiency of food-based lures. Our results have application for pest management in New Zealand and the technique of using kairomones to monitor predators could have applications for conservation efforts worldwide.
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Affiliation(s)
- Patrick M Garvey
- Centre for Biodiversity and Biosecurity, School of Biological Sciences, University of Auckland, Auckland, New Zealand
- Landcare Research, Private Bag 92170, Auckland, 1142, New Zealand
| | - Alistair S Glen
- Landcare Research, Private Bag 92170, Auckland, 1142, New Zealand
| | - Mick N Clout
- Centre for Biodiversity and Biosecurity, School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Sarah V Wyse
- Centre for Biodiversity and Biosecurity, School of Biological Sciences, University of Auckland, Auckland, New Zealand
- Royal Botanic Gardens Kew, Wakehurst Place, RH17 6TN, United Kingdom
| | - Margaret Nichols
- Centre for Wildlife Management and Conservation, Lincoln University, Canterbury, New Zealand
| | - Roger P Pech
- Landcare Research, PO Box 69040, Lincoln, 7640, New Zealand
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Goldson SL, Bourdôt GW, Brockerhoff EG, Byrom AE, Clout MN, McGlone MS, Nelson WA, Popay AJ, Suckling DM, Templeton MD. New Zealand pest management: current and future challenges. J R Soc N Z 2015. [DOI: 10.1080/03036758.2014.1000343] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Etherington TR, Perry GLW, Cowan PE, Clout MN. Quantifying the direct transfer costs of common brushtail possum dispersal using least-cost modelling: a combined cost-surface and accumulated-cost dispersal kernel approach. PLoS One 2014; 9:e88293. [PMID: 24505467 PMCID: PMC3914968 DOI: 10.1371/journal.pone.0088293] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Accepted: 01/06/2014] [Indexed: 11/21/2022] Open
Abstract
Dispersal costs need to be quantified from empirical data and incorporated into dispersal models to improve our understanding of the dispersal process. We are interested in quantifying how landscape features affect the immediately incurred direct costs associated with the transfer of an organism from one location to another. We propose that least-cost modelling is one method that can be used to quantify direct transfer costs. By representing the landscape as a cost-surface, which describes the costs associated with traversing different landscape features, least-cost modelling is often applied to measure connectivity between locations in accumulated-cost units that are a combination of both the distance travelled and the costs traversed. However, we take an additional step by defining an accumulated-cost dispersal kernel, which describes the probability of dispersal in accumulated-cost units. This novel combination of cost-surface and accumulated-cost dispersal kernel enables the transfer stage of dispersal to incorporate the effects of landscape features by modifying the direction of dispersal based on the cost-surface and the distance of dispersal based on the accumulated-cost dispersal kernel. We apply this approach to the common brushtail possum (Trichosurus vulpecula) within the North Island of New Zealand, demonstrating how commonly collected empirical dispersal data can be used to calibrate a cost-surface and associated accumulated-cost dispersal kernel. Our results indicate that considerable improvements could be made to the modelling of the transfer stage of possum dispersal by using a cost-surface and associated accumulated-cost dispersal kernel instead of a more traditional straight-line distance based dispersal kernel. We envisage a variety of ways in which the information from this novel combination of a cost-surface and accumulated-cost dispersal kernel could be gainfully incorporated into existing dispersal models. This would enable more realistic modelling of the direct transfer costs associated with the dispersal process, without requiring existing dispersal models to be abandoned.
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Affiliation(s)
| | - George L. W. Perry
- School of Environment, The University of Auckland, Auckland, New Zealand
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | | | - Mick N. Clout
- School of Environment, The University of Auckland, Auckland, New Zealand
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
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Galbraith JA, Fraser EA, Clout MN, Hauber ME. Survey duration and season influence the detection of introduced eastern rosella (Platycercus eximius) in New Zealand. New Zealand Journal of Zoology 2011. [DOI: 10.1080/03014223.2011.584541] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Blackie HM, Russell JC, Clout MN. Maternal influence on philopatry and space use by juvenile brushtail possums (Trichosurus vulpecula). J Anim Ecol 2010; 80:477-83. [DOI: 10.1111/j.1365-2656.2010.01781.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Rayner MJ, Carraher CJF, Clout MN, Hauber ME. Mitochondrial DNA analysis reveals genetic structure in two New Zealand Cook’s petrel (Pterodroma cookii) populations. CONSERV GENET 2010. [DOI: 10.1007/s10592-010-0072-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Affiliation(s)
- Mick N. Clout
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
- * E-mail:
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Abstract
Of the extant species of land mammals, 124 (2.6%) can be classed as ‘successful invaders’, whereas 1038 (21.6%) are classed as threatened, according to the 2006 IUCN Red List. Relatively high proportions of successful invaders are found among Artiodactyla, Carnivora, Lagomorpha and Perissodactyla. Compared with other organisms, mammals seem relatively likely to become established when introduced outside their natural range. Studies of determinants of invasion success indicate that the number of individuals released, the size of the natural range of the introduced species, and the temperateness of climate in the new range can all increase the probability of establishment of introduced mammals. Negative impacts of invasive mammals on native biodiversity include direct effects such as predation, browsing and competition, but can extend to disruption of patterns of nutrient flow, and trophic cascades. Eradication of several species of invasive mammals from increasingly large areas is now possible. In this context, it is important to better understand ecological interactions between such mammals (and between them and other species) to avoid unwanted consequences such as mesopredator or competitor release, after the removal of particular species. Finally, it is increasingly apparent that research is needed on the behaviour of dispersing and invading individuals, to improve the early detection of new mammal invasions or reinvasions.
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White PCL, Ford AES, Clout MN, Engeman RM, Roy S, Saunders G. Alien invasive vertebrates in ecosystems: pattern, process and the social dimension. Wildl Res 2008. [DOI: 10.1071/wr08058] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The rate of biological invasions has increased dramatically over recent centuries. Alien invasive vertebrates have significant adverse effects on biodiversity, and island fauna are especially susceptible. Human-induced environmental change is likely to exacerbate these negative impacts of alien invasive species. However, invasion biology has advanced considerably over the last two decades, with improvement in understanding of the processes of establishment and spread. New developments in spatial modelling have elucidated the way in which behavioural processes at the individual level can drive population-level patterns such as spread. Combined with new genetic insights into the process of invasion, these advances may assist in the development of novel, better-targeted management strategies that provide new options in how to deal with the threat posed by invasive species. Decisions about whether to and how we should intervene are questions for all sectors of society, but research on the social and cultural impacts of invasive species is largely lacking. There are many opportunities for enhancing the social dimensions of invasive species research, and integrated assessments of the social, economic and environmental impacts of species provide one potential avenue. As part of this, there is also a need to increase stakeholder participation in the decision-making process regarding alien invasive species. These more holistic approaches are essential if we are to reduce the impact of alien invasive species to within acceptable limits in the face of rapid environmental change.
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Abstract
Rats continue to invade rat-free islands around the world, and it remains difficult to successfully intercept them before they establish populations. Successful biosecurity methods should intercept rats rapidly, before they can establish a population. Current island biosecurity practice employs techniques used for high-density rat eradication, assuming that they will be equally effective on low-density invaders. However, such approaches are often untested. Adult male Norway rats (Rattus norvegicus) were individually released onto forested rat-free islands in New Zealand to test methods of detecting and eliminating a single invader. Only half the rats released were caught within a two-week timeframe, although the mean time to interception was just under 14 days. Permanent island biosecurity surveillance systems performed better than contingency responses. Success rates were higher on islands where complete coverage could be obtained, although surveillance systems using multiple devices eventually detected most invading rats. For some rats a change of methods was necessary. Single invading rats left a rat-free island despite the presence of excessive natural food resources. With surveillance systems comprising an array of tested island biosecurity devices, and where necessary a contingency response using alternative methods, it should be possible to maintain islands as rat-free even when they have a high reinvasion rate.
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Abstract
Supplementary feeding is often a key tool in the intensive management of captive and threatened species. Although it can increase such parameters as breeding frequency and individual survival, supplementary feeding may produce undesirable side effects that increase overall extinction risk. Recent attempts to increase breeding frequency and success in the kakapo Strigops habroptilus using supplementary feeding inadvertently resulted in highly male-biased chick sex ratios. Here, we describe how the inclusion of sex allocation theory has remedied this conservation dilemma. Our study is the first to manipulate chick sex ratios in an endangered species by altering maternal condition and highlights the importance of incorporating evolutionary theory into modern conservation practice.
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Affiliation(s)
- Bruce C Robertson
- University of Canterbury, School of Biological Sciences, PB 4800, Christchurch, New Zealand.
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Ward DF, Beggs JR, Clout MN, Harris RJ, O'Connor S. The diversity and origin of exotic ants arriving in New Zealand via human-mediated dispersal. DIVERS DISTRIB 2006. [DOI: 10.1111/j.1366-9516.2006.00270.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Abstract
A single Norway rat released on to a rat-free island was not caught for more than four months, despite intensive efforts to trap it. The rat first explored the 9.5-hectare island and then swam 400 metres across open water to another rat-free island, evading capture for 18 weeks until an aggressive combination of detection and trapping methods were deployed simultaneously. The exceptional difficulty of this capture indicates that methods normally used to eradicate rats in dense populations are unlikely to be effective on small numbers, a finding that could have global implications for conservation on protected islands.
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Affiliation(s)
- James C Russell
- School of Biological Sciences, Private Bag 92019, Auckland, New Zealand.
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Abstract
Brushtail possums (Trichosurus vulpecula) were live-trapped for two years prior to and following depopulation in two ~6-ha areas of native forest in New Zealand. The populations had recovered to 55% of the original density at one site and 40% of the original density at the other site, two years after the depopulation. The post-removal populations responded to reduced density with a higher proportion of females breeding, higher survival rate of young, and less seasonal fluctuation in body condition. The initial recolonisation was probably mainly due to surrounding animals shifting their ranges into the depopulated area, rather than long-range dispersal, which resulted in an even sex ratio in the recovering populations. The greater proportion of adult males in the post-removal populations is likely to increase sexual contact rates for females. This would enhance the dissemination of a viral-vectored biological control agent through the population, when used as part of an integrated control program.
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Ji W, Sarre SD, Craig JL, Clout MN. DENNING BEHAVIOR OF COMMON BRUSHTAIL POSSUMS IN POPULATIONS RECOVERING FROM DENSITY REDUCTION. J Mammal 2003. [DOI: 10.1644/bos-030] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Ji W, Sarre SD, Aitken N, Hankin RK, Clout MN. Sex-biased dispersal and a density-independent mating system in the Australian brushtail possum, as revealed by minisatellite DNA profiling. Mol Ecol 2001; 10:1527-37. [PMID: 11412373 DOI: 10.1046/j.1365-294x.2001.01287.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Natal dispersal can have important effects on mammal population structure and dynamics following a local population crash. Such dispersal is of practical importance when applied to the control of pest species because dispersal may significantly, and undesirably, reduce the population recovery time following a control operation. The relative dispersal rate of the sexes is also critical because that too will affect the rate of population increase. Here, we describe a field experiment in which we reduce the density of two populations of the Australian brushtail possum, and use genetic similarity, as estimated by minisatellite DNA profiles, to investigate dispersal in the original (undisturbed) and recovering populations. Our results show that the genetic similarity within the undisturbed populations was lower between males than between females. Conversely, the genetic similarities between males and females in the two recovering populations were not significantly different, while relatedness among males was significantly higher in the recovering populations when compared with those in the pre-removal populations. These data indicate two important characteristics of dispersal in possums: (i) that dispersal in established populations is sex biased towards males; and (ii) that within the first 3 years following population control, 'the vacuum effect', whereby individuals from areas adjacent to a control area expand their home range and invade the depopulated area, is the most important factor in the re-colonization process for possums. We found no evidence that the mating system, which is polygynous, varied when the density was markedly reduced. These results indicate that drastic reductions in population density by conventional control will not affect the rate of spread of biological control agents that rely on sexual transmission for dissemination.
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Affiliation(s)
- W Ji
- School of Environmental and Marine Sciences, The University of Auckland, PB 92019, Auckland, New Zealand.
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20
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Abstract
Many studies in molecular ecology have focused on the use of repeat DNA markers to determine the nature of mating systems in a wide variety of animal species. Whilst these studies typically have focused on important issues such as the evolutionary consequences of fitness variation among males, genetic studies of mating systems are potentially also important because they can generate information of significance to wider issues in wildlife management. For example, genetically modified, sexually transmitted viral diseases have been suggested as potential agents for the control of vertebrate pest species. An understanding of the epidemiology of such agents requires an intimate knowledge of the sexual contact rates between individuals of the target species. Here, we report the use of minisatellite DNA profiling to reveal the mating system in two New Zealand populations of the introduced Australian brushtail possum. The brushtail possum is New Zealand's most important mammalian pest and a species for which control by a sexually transmitted immunocontraceptive has been proposed. Encouragingly, we report considerable variation in the reproductive success of males at both study sites, with one male siring offspring from four females in one year (mean no. of offspring/reproductively successful male/year at the two sites is 1.95-2.15), while many sired none. This bias in the pattern of reproductive success among males will probably facilitate the spread of an immunocontraceptive agent and thereby increase the power of this approach to biological control.
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Affiliation(s)
- S D Sarre
- Institute of Molecular Biosciences, Massey University, Private Bag 11-222, Palmerston North, New Zealand,School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand. Anthropology, University of Auckland, Private
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Abstract
The foraging behaviour of glossy black-cockatoos (Calyptorhynchus lathami) was studied in eucalypt
forests near Eden, New South Wales, Australia, from June 1982 to February 1983. In this area, the
cockatoos fed solely on Allocasuarina littoralis seeds that they extracted from closed cones, leaving
characteristic feeding litter beneath favoured trees. The cockatoos bred in winter and apparently raised
their young entirely on A. littoralis seeds. They spent 88% of the day foraging. The basis on which
the cockatoos selected particular A. littoralis trees in which to forage was investigated. They chose
trees with larger cone crops but showed no evidence of selecting trees on the basis of cone size.
They concentrated their foraging in trees bearing cones with a high ratio of total seed weight to cone
weight, which is an index of the potential return (i.e. seeds) from each cone-opening effort.
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