Linking Plant Invasions to Global Environmental Change

  • Montserrat Vilà
  • Jeffrey D. Corbin
  • Jeffrey S. Dukes
  • Joan Pino
  • Stanley D. Smith
Part of the Global Change — The IGBP Series book series (GLOBALCHANGE)

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References

  1. Aber JD, McDowell WH, Nadelhoffer KJ, Magill A, Berntson G, Kamakea M, McNulty SG, Currie W, Rustad L, Fernandez I (1998) Nitrogen saturation in temperate forest ecosystems: Hypotheses revisited. BioScience 48:921–934CrossRefGoogle Scholar
  2. Aber JD, Nadelhoffer KJ, Steduler P, Melillo JM (1989) Nitrogen saturation in northern forest ecosystems. BioScience 39:378–386CrossRefGoogle Scholar
  3. Allen EB (2003) Restoration of Artemisia shrublands invaded by exotic annual Bromus: A comparison between southern California and the Intermountain region. In: Hild AL, Shaw NL, Meyer SE, Schupp EW, Booth T (Compilers) Seed and soil dynamics in shrubland ecosystems: Proceedings; August 12–16, 2002, Laramie, Wyoming, Proceedings RMRS-P-31. U.S. Department of Agriculture Forest Service, Rocky Mountain Research Station, Ogden, Utah, pp 9–17Google Scholar
  4. Baruch Z, Goldstein G (1999) Leaf construction cost, nutrient concentration and net CO2 assimilation of native and invasive species in Hawaii. Oecologia 121:183–192CrossRefGoogle Scholar
  5. Beerling DJ, Huntley B, Bailey JP (1995) Climate and the distribution of Fallopia japonica: use of an introduced species to test the predictive capacity of response surfaces. Journal of Vegetation Science 6:269–282CrossRefGoogle Scholar
  6. Belote RT, Weltzin JF, Norby RJ (2003) Response of an understory plant community to elevated [CO2] depends on differential responses of dominant invasive species and is mediated by soil water availability. New Phytologist 161:827–835CrossRefGoogle Scholar
  7. Bobbink R (1991) Effects of nutrient enrichment in Dutch chalk grasslands. Journal of Applied Ecology 28:28–41CrossRefGoogle Scholar
  8. Bobbink R, Hornung M, Roelofs JGM (1998) The effects of air-borne nitrogen pollutants on species diversity in natural and seminatural European vegetation. Journal of Ecology 86:717–738CrossRefGoogle Scholar
  9. Boutin C, Jobin B (1998) Intensity of agricultural practices and effects on adjacent habitats. Ecological Applications 8:544–557CrossRefGoogle Scholar
  10. Brooks ML (1999) Alien annual grasses and fire in the Mojave Desert. Madroño 46:13–19Google Scholar
  11. Brooks ML (2003) Effects of increased soil nitrogen on the dominance of alien annual plants in the Mojave Desert. Journal of Applied Ecology 40:344–353Google Scholar
  12. Brown VC (1995) Insect herbivores and gaseous air pollutants: current knowledge and predictions. In: Harrington R, Stork NE (eds) Insects in a changing environment. Academic Press, London, pp 22–29Google Scholar
  13. Corbin JD, D’Antonio CM (2004) Effects of invasive species on soil nitrogen cycling: Implications for restoration. Weed Technology 18:1464–1467CrossRefGoogle Scholar
  14. D’Antonio CM, Corbin JD (2003) Effects of plant invaders on nutrient cycling: Using models to explore the link between invasion and development of species effects. In: Canham CD, Cole JC, Lauenroth WK (eds) Models in ecosystem science. Princeton University Press, Princeton, pp 363–384Google Scholar
  15. D’Antonio CM, Vitousek PM (1992) Biological invasions by exotic grasses, the grass/fire cycle, and global change. Annual Review of Ecology and Systematics 23:63–87Google Scholar
  16. D’Antonio CM, Dudley TL, Mack MC (1999) Disturbance and biological invasions: direct effects and feedbacks. In: Walker LR (ed) Ecosystems of disturbed ground. Elsevier, New York, New York, USA, pp 413–452Google Scholar
  17. DeVries W, Leeters EM, Hendricks CA (1995) Effects of acid deposition on Dutch forest ecosystems. Water, Air and Soil Pollution 85:1063–1068CrossRefGoogle Scholar
  18. Dukes JS (2000) Will the increasing atmospheric CO2 concentration affect the success of invasive species? In: Mooney HA, Hobbs RJ (eds) Invasive Species in a Changing World. Island Press, Washington, DC, pp 95–113Google Scholar
  19. Dukes JS (2002) Comparison of the effect of elevated CO2 on an invasive species (Centaurea solstitialis) in monoculture and community settings. Plant Ecology 160:225–234CrossRefGoogle Scholar
  20. Dukes JS, Mooney HA (1999) Does global change increase the success of biological invaders? Trends in Ecology and Evolution 14:135–139CrossRefGoogle Scholar
  21. Ehleringer JR, Cerling TE, Helliker BR (1997) C4 photosynthesis, atmospheric CO2 and climate. Oecologia 112:285–299CrossRefGoogle Scholar
  22. Ehrenfeld J (2003) Effects of exotic plant invasions of ecosystem nutrient cycling processes. Ecosystems 6:503–523CrossRefGoogle Scholar
  23. Falkengren-Grerup U (1986) Soil acidification and vegetation changes in deciduous forests in southern Sweden. Oecologia 70:339–347CrossRefGoogle Scholar
  24. Fenn ME, Poth MA, Aber JD, Baron JS, Bormann BT, Johnson DW, Lemly AD, McNulty SG, Ryan DF, Stottlemyer R (1998) Nitrogen excess in North American ecosystems: Predisposing factors, ecosystem responses, and management strategies. Ecological Applications 8:706–733CrossRefGoogle Scholar
  25. Fenn ME, Haeuber R, Tonnesen GS, Baron JS, Grossman-Clarke S, Hope D, Jaffe DA, Copeland S, Geisher L, Rueth HM, Sickman JO (2003a) Nitrogen emissions, deposition, and monitoring in the western United States. BioScience 53:391–403CrossRefGoogle Scholar
  26. Fenn ME, Baron JS, Allen EB, Rueth HM, Nydick KR, Geiser L, Bowman WD, Sickman JO, Meixner T, Johnson DW, Neitlich P (2003b) Ecological effects of nitrogen deposition in the western United States. BioScience 53:404–420CrossRefGoogle Scholar
  27. Galloway JN, Schlesinger WH, Levy H II, Michaels A, Schnoor JL (1995) Nitrogen fixation: Anthropogenic enhancement — environmental response. Global Biogeochemical Cycles 9:235–252CrossRefGoogle Scholar
  28. Galloway JN, Aber JD, Erisman JW, Seitzinger SP, Howarth RW, Cowling EB, Cosby BJ (2003) The nitrogen cascade. BioScience 53:341–356CrossRefGoogle Scholar
  29. Gelbard JL, Belnap J (2003) Roads as conduits for exotic plant invasions in a semiarid landscape. Conservation Biology 17:420–432CrossRefGoogle Scholar
  30. Grotkopp E, Rejmánek M, Rost TL (2002) Toward a causal explanation of plant invasiveness: seedling growth and life-history strategies of 29 pine (Pinus) species. The American Naturalist 159:396–419CrossRefGoogle Scholar
  31. Hättenschwiler S, Körner C (2003) Does elevated CO2 facilitate naturalization of the non-indigenous Prunus laurocerasus in Swiss temperate forests? Functional Ecology 17:778–785CrossRefGoogle Scholar
  32. Hobbs RJ (2000) Land-use Changes and Invasions. In: Mooney HA, Hobbs RJ (eds) Invasive species in a changing world. Island Press, Washington, pp 55–64Google Scholar
  33. Hobbs RJ, Huenneke LF (1992) Disturbance, diversity, and invasion: implications for conservation. Conservation Biology 6:324–337CrossRefGoogle Scholar
  34. Hogbom L, Hogberg P (1991) Nitrate nutrition of Deschampsia flexuosa (L.) Trin. in relation to nitrogen deposition in Sweden. Oecologia 87:488–494CrossRefGoogle Scholar
  35. Huenneke LF, Hamburg SP, Koide R, Mooney HA, Vitousek PM (1990) Effects of soil resources on plant invasion and community structure in California serpentine grassland. Ecology 71:478–491CrossRefGoogle Scholar
  36. Huxman TE, Smith SD (2001) Photosynthesis in an invasive grass and native forb at elevated CO2 during an El Niño year in the Mojave Desert. Oecologia 128:193–201CrossRefGoogle Scholar
  37. Huxman TE, Hamerlynck EP, Jordan DN, Salsman KJ, Smith SD (1998) The effects of parental CO2 environment on seed quality and subsequent seedling performance in Bromus rubens. Oecologia 114:202–208CrossRefGoogle Scholar
  38. Huxman TE, Hamerlynck EP, Smith SD (1999) Reproductive allocation and seed production in Bromus madritensis ssp. rubens at elevated atmospheric CO2. Functional Ecology 13:769–777CrossRefGoogle Scholar
  39. IPCC (2001) Climate Change 2001: Impacts, Adaptation, and Vulnerability. Contribution of Working Group II to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United KingdomGoogle Scholar
  40. Jackson R, Jobbagy E (2007) Vegetation changes and carbon and water dynamics. In: Canadell J, Pataki D, Pitelka L (eds) Terrestrial ecosystems in a changing world. Springer-Verlag, BerlinGoogle Scholar
  41. Jefferies RL, Maron JL (1997) The embarrassment of riches: atmospheric deposition of nitrogen and community and ecosystem processes. Trends in Ecology and Evolution 12:74–78CrossRefGoogle Scholar
  42. Jenkins JC, Aber JD, Canham (1999) Hemlock woolly adelgid impacts on community structure and N cycling rates in eastern hemlock forests. Canadian Journal of Forest Research 29:630–645CrossRefGoogle Scholar
  43. Kellner O (1993) Effects on associated flora of sylvicultural nitrogen fertilization repeated at long intervals. Journal of Applied Ecology 30:563–574CrossRefGoogle Scholar
  44. Knapp PA (1998) Spatio-temporal patterns of large grassland fires in the Intermountain West, U.S.A. Global Ecol Biogeogr 7:259–272CrossRefGoogle Scholar
  45. Kriticos DJ, Sutherst RW, Brown JR, Adkins SW, Maywald GF (2003a) Climate change and biotic invasions: a case history of a tropical woody vine. Biological Invasions 5:145–165CrossRefGoogle Scholar
  46. Kriticos DJ, Sutherst RW, Brown JR, Adkins SW, Maywald GF (2003b) Climate change and the potential distribution of an invasive alien plant: Acacia nilotica ssp indica in Australia. Journal of Applied Ecology 40:111–124CrossRefGoogle Scholar
  47. Latty EF, Canham CD, Marks PL (2003) Beech bark disease in northern hardwood forests: the importance of nitrogen dynamics and forest history for disease severity. Canadian Journal of Forest Research 33:257–268CrossRefGoogle Scholar
  48. Lavorel S, DÍaz S, Pausas J, Garnier E, Neilson R (2007) Plant functional types: are we getting any closer to the Holy Grail? In: Canadell J, Pataki D, Pitelka L (eds) Terrestrial ecosystems in a changing world. Springer-Verlag, BerlinGoogle Scholar
  49. Le Maitre DC, Wilgen BV, Chapman R, McKelly D (1996) Invasive plants and water resources in the Eastern Cape Province, South Africa: modelling the consequences of a lack of management. Journal of Applied Ecology 33:161–172CrossRefGoogle Scholar
  50. Levine JM, Vilà M, D’Antonio CM, Dukes JS, Grigulis K, Lavorel S (2003) Mechanisms underlying the impact of exotic plant invasions. Philosophical Transactions of the Royal Society of London B 270:775–781Google Scholar
  51. Liebhold AM, MacDonald WL, Bergdahl D, Mastro VC (1995) Invasion by exotic forest pests: A threat to forest ecosystems. Forest Science Monographs 30:1–49Google Scholar
  52. Lockwood JL, Mckinney ML (2001) Biotic homogenization. Kluwer Academic. Plenum Publishers, New YorkGoogle Scholar
  53. Mack RN (1981) Invasion of Bromus tectorum L. into western North America: an ecological chronicle. Agro-Ecosystems 7:145–165CrossRefGoogle Scholar
  54. Mack MC, D’Antonio CM (1998) Impacts of biological invasions on disturbance regimes. Trends in Ecology and Evolution 13:195–198CrossRefGoogle Scholar
  55. Malcolm JR, Markham A, Neilson RP, Garaci M (2002) Estimated migration rates under scenarios of global climate change. Journal of Biogeography 29:835–849CrossRefGoogle Scholar
  56. Maron JL, Connors PG (1996) A native nitrogen-fixing shrub facilitates weed invasion. Oecologia 105:302–312CrossRefGoogle Scholar
  57. McNeely JA (2001) The great reshuffling. Human dimensions of invasive alien species. IUCN, CambridgeGoogle Scholar
  58. Moore PD (2004) Favoured aliens for the future. Nature 427:594CrossRefGoogle Scholar
  59. Murphy DD, Ehrlich PR (1989) Conservation biology of California’s remnant native grasslands. In: Huenneke LF, Mooney HA (eds) Grassland structure and function: The California annual grassland. Klewer Academic Publishers, The Netherlands, pp 201–211Google Scholar
  60. Nagel JM, Griffin KL (2001) Construction cost and invasive potential: comparing Lythrum salicaria (Lythraceae) with co-occurring native species along pond banks. American Journal of Botany 88:2252–2258Google Scholar
  61. Nagel JM, Griffin KL (2004) Can gas-exchange characteristics help explain the invasive success of Lythrum salicaria? Biological Invasions 6:101–111CrossRefGoogle Scholar
  62. Nagel JM, Huxman TE, Griffin KL, Smith SD (2004) CO2 enrichment reduces the energetic cost of biomass construction in an invasive desert grass. Ecology 85:100–106Google Scholar
  63. Norby R, Rustad L, Beier C, Zavaleta E, Parton B, McMurtrie R (2007) Multiple factor interactions on ecosystem function (CO2, temperature, nutrients, water (TERACC)). In: Canadell J, Pataki D, Pitelka L (eds) Terrestrial ecosystems in a changing world. Springer-Verlag, BerlinGoogle Scholar
  64. Parendes LA, Jones JA (1999) Role of light availability and dispersal in exotic plant invasion along roads and streams in the HJ Andrews Experimental Forest, Oregon. Conservation Biology 14:64–75CrossRefGoogle Scholar
  65. Parmesan C, Yohe G (2003) A globally coherent fingerprint of climate change impacts across natural systems. Nature 421:37–42CrossRefGoogle Scholar
  66. Patterson DT (1995) Weeds in a changing climate. Weed Science 43:685–701Google Scholar
  67. Peñuelas J, Filella I, Comas P (2002) Changed plant and animal life cycles from 1952 to 2000 in the Mediterranean region. Global Change Biology 8:531–544CrossRefGoogle Scholar
  68. Peterson AT, Vieglais DA (2001) Predicting the species invasions using ecological niche modeling: New approaches from bioinformatics attack a pressing problem. BioScience 51:363–371CrossRefGoogle Scholar
  69. Peterson AT, Papes M, Kluza DA (2003) Predicting the potential invasive distribution of four alien plant species in North America. Weed Science 51:863–868CrossRefGoogle Scholar
  70. Pino J, Font X, Carbó J, Jové M, Pallarés L (2005) Large-scale correlates of alien plant invasion in Catalonia (NE Spain). Biological Conservation 122:339–350CrossRefGoogle Scholar
  71. Pino J, SeguÍ JM, Alvarez N (2006) Invasibility of four plant communities in the Llobregat delta (Catalonia, NE of Spain) in relation to their historical stability. Hydrobiologia 570:257–263CrossRefGoogle Scholar
  72. Pysek P, Prach K, Mandák B (1998) Invasions of alien plants into habitats of central european landscape: an historical pattern. In: Starfinger U, Edwards K, Kowarik I, Williamson M, editors. Plant invasions: ecological mechanisms and human responses. Backhuys Publishers, Leiden, pp 23–32Google Scholar
  73. Rejmánek M (1996) A theory of seed plant invasiveness: the first sketch. Biological Conservation 78:171–181CrossRefGoogle Scholar
  74. Rejmánek M (2000) Invasive plants: approaches and predictions. Austral Ecology 25:497–506CrossRefGoogle Scholar
  75. Reynolds JF, Maestre F, Lambin EF, Stafford-Smith DM, Valentin C (2007) Natural and human dimensions of land degradation: causes and consequences. In: Canadell J, Pataki D, Pitelka L (eds) Terrestrial ecosystems in a changing world. Springer-Verlag, BerlinGoogle Scholar
  76. Richardson DM, Allsopp N, D’Antonio CM, Milton SJ, Rejmánek M (2000a) Plant invasions — the role of mutualisms. Biological Reviews 75:65–93Google Scholar
  77. Richardson DM, Bond WJ, Dean RJ, Higgins SI, Midgley GF, Milton SJ, Powrie LW, Rutherford MC, Samways MJ, Schulze RE (2000b) In: Mooney HA, Hobbs RJ (eds) Invasive alien species and global change: a South African perspective. Invasive species in a changing world. Island Press, Washington, pp 303–349Google Scholar
  78. Romney EM, Wallance A, Hunter RB (1978) Plant response to nitrogen fertilization in the Northern Mojave Desert and its relationship to water manipulation. In: West NE, Skujins J (eds) Nitrogen in desert ecosystems. Dowden, Hutchinson & Ross Inc., Stroudsburg, pp 232–243Google Scholar
  79. Root TL, Price JT, Hall KR, Schneider SH, Rosenzweig C, Pounds JA (2003) Fingerprints of global warming on wild animals and plants. Nature 421:57–60CrossRefGoogle Scholar
  80. Rosen K, Gunderson P, Tegnhammer L, Johansson M, Frogner T (1992) Nitrogen enrichment of Nordic forests: the concept of critical loads. Ambio 21:364–368Google Scholar
  81. Roura-Pascual N, Suarez AV, Gómez C, Pons P, Touyama Y, Wild AL, Peterson AT (2004) Geographical potential of Argentine ants (Linepithema humile Mayr) in the face of global climate change. Proceedings of the Royal Society of London 271:2527–2534CrossRefGoogle Scholar
  82. Sasek TW, Strain BR (1991) Effects of CO2 enrichment on the growth and morphology of a native and an introduced honeysuckle vine. American Journal of Botany 78:69–75CrossRefGoogle Scholar
  83. Smith SD, Strain BR, Sharkey TD (1987) Effects of CO2 enrichment on four Great Basin grasses. Functional Ecology 1:139–143CrossRefGoogle Scholar
  84. Smith SD, Huxman TE, Zitzer SF, Charlet TN, Housman DC, Coleman JS, Fenstermaker LK, Seemann JR, Nowak RS (2000) Elevated CO2 increases productivity and invasive species success in an arid ecosystem. Nature 408:79–82CrossRefGoogle Scholar
  85. Soulé ME (1991) Conservation: tactics for a constant crisis. Science 253:744–750CrossRefGoogle Scholar
  86. Stevens CJ, Dise NB, Mountford JO, Gowing DJ (2004) Impact of nitrogen deposition on the species richness of grasslands. Science 303:1876–1879CrossRefGoogle Scholar
  87. Thimoneir A, Dupouey JL, Timbal J (1992) Floristic changes in the herb-layer vegetation of a deciduous forest in the Lorraine Plain under the influence of atmospheric deposition. Forest Ecology and Management 55:149–167CrossRefGoogle Scholar
  88. Throop HL, Lerdau MT (2004) Effects of nitrogen deposition on insect herbivory: Implications for community and ecosystem processes. Ecosystems 7:109–133CrossRefGoogle Scholar
  89. Tyser RW, Worley CA (1992) Alien flora in grasslands adjacent to road and trail corridors in Glacier National Park, Montana (U.S.A.). Conservation Biology 6:253–262CrossRefGoogle Scholar
  90. van Breemen N, van Dijk HFG (1988) Ecosystem effects of atmospheric deposition on nitrogen in The Netherlands. Environmental Pollution 54:249–274CrossRefGoogle Scholar
  91. Vane-Wright RI, Humphries CJ, Williams PH (1991) What to protect? Systematics and the agony of choice. Biological Conservation 55:235–254CrossRefGoogle Scholar
  92. Vilà M, Pujadas J (2001) Land-use and socio-economic correlates of plant invasions in European and North African countries. Biological Conservation 100:397–401CrossRefGoogle Scholar
  93. Vilà M, Burriel JA, Pino J, Chamizo J, Llach E, Porterias M, Vives M (2003) Association between Opuntia spp. invasion and changes in land-cover in the Mediterranean region. Global Change Biology 9:1234–1239CrossRefGoogle Scholar
  94. Vinton MA, Burke IC (1995) Interactions between individual plant species and soil nutrient status in shortgrass steppe. Ecology 76:1116–1133CrossRefGoogle Scholar
  95. Vitousek P (1994) Beyond global warming: ecology and global change. Ecology 75:1861–1876CrossRefGoogle Scholar
  96. Vitousek PM, Howarth RW (1991) Nitrogen limitation of land and sea: How can it occur? Biogeochemistry 13:87–115CrossRefGoogle Scholar
  97. Vitousek PM, Walker LR, Whiteaker LD, Mueller-Dombois D, Matson PA (1987) Biological invasion by Myrica faya alters ecosystem development in Hawaii. Science 238:802–804CrossRefGoogle Scholar
  98. Vitousek PM, Howarth RW, Likens GE, Matson PA, Schindler D, Schlesinger WH, Tilman GD (1997) Human alteration of the global nitrogen cycle: Causes and consequences. Issues in Ecology 1:1–17Google Scholar
  99. Walther GR (2002) Weakening of climatic constraints with global warming and its consequences for evergreen broad-leaved species. Folia Geobotanica 37:129–139Google Scholar
  100. Wedin DA, Tilman D (1996) Influence of nitrogen loading and species composition on the carbon balance of grasslands. Science 274:1720–1723CrossRefGoogle Scholar
  101. Weiss SB (1999) Cars, cows, and checkerspot butterflies: Nitrogen deposition and management of nutrient-poor grasslands for a threatened species. Conservation Biology 13:1476–1486CrossRefGoogle Scholar
  102. White TA, Campbell BD, Kemp PD, Hunt CL (2000) Sensitivity of three grassland communities to simulated extreme temperature and rainfall events. Global Change Biology 6:671–684CrossRefGoogle Scholar
  103. White TA, Campbell BD, Kemp PD, Hunt CL (2001) Impacts of extreme climatic events on competition during grassland invasions. Global Change Biology 7:1–13CrossRefGoogle Scholar
  104. With KA (2002) The landscape ecology of invasive spread. Conservation Biology 16:1192–1203CrossRefGoogle Scholar
  105. Young JA, Evans RA (1978) Population dynamics after wildfires in sagebrush grasslands. Journal of Range Management 31:283–289Google Scholar
  106. Zavaleta ES, Royval JL (2002) Climate change and the susceptibility of U.S. ecosystems to biological invasions: two cases of expected range expansion. In: Root TL (ed) Wildlife Responses to Climate Change. Island Press, Washington, pp 277–341Google Scholar
  107. Ziska LH (2002) Influence of rising atmospheric CO2 since 1900 on early growth and photosynthetic response of a noxious invasive weed, Canada thistle (Cirsium arvense). Functional Plant Biology 29:1387–1392CrossRefGoogle Scholar
  108. Ziska LH (2003) Evaluation of the growth response of six invasive species to past, present and future atmospheric carbon dioxide. Journal of Experimental Botany 54:395–404CrossRefGoogle Scholar
  109. Ziska LH, Caulfield FA (2000) Rising CO2 and pollen production of common ragweed (Ambrosia artemisiifolia), a known allergyinducing species: implications for public health. Australian Journal of Plant Physiology 27:893–898Google Scholar

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© Springer-Verlag Berlin Heidelberg 2007

Authors and Affiliations

  • Montserrat Vilà
    • 1
  • Jeffrey D. Corbin
    • 2
  • Jeffrey S. Dukes
    • 3
  • Joan Pino
    • 4
  • Stanley D. Smith
    • 5
  1. 1.Center for Ecological Research and Forestry ApplicationsBarcelona, CataloniaSpain
  2. 2.Department of Integrative BiologyUniversity of CaliforniaBerkeleyUSA
  3. 3.Department of BiologyUniversity of MassachusettsBostonUSA
  4. 4.Center for Ecological Research and Forestry ApplicationsBellaterra, CataloniaSpain
  5. 5.Department of Biological SciencesUniversity of NevadaLas VegasUSA

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