Skip to main content
×
×
Home

Genetic erosion in crops: concept, research results and challenges

  • Mark van de Wouw (a1), Chris Kik (a1), Theo van Hintum (a1), Rob van Treuren (a1) and Bert Visser (a1)...
Abstract

The loss of variation in crops due to the modernization of agriculture has been described as genetic erosion. The current paper discusses the different views that exist on the concept of genetic erosion in crops. Genetic erosion of cultivated diversity is reflected in a modernization bottleneck in the diversity levels that occurred during the history of the crop. Two stages in this bottleneck are recognized: the initial replacement of landraces by modern cultivars; and further trends in diversity as a consequence of modern breeding practices. Genetic erosion may occur at three levels of integration: crop, variety and allele. The different approaches in the recent literature to measure genetic erosion in crops are reviewed. Genetic erosion as reflected in a reduction of allelic evenness and richness appears to be the most useful definition, but has to be viewed in conjunction with events at variety level. According to the reviewed literature, the most likely scenario of diversity trends during modernization is the following: a reduction in diversity due to the replacement of landraces by modern cultivars, but no further reduction after this replacement has been completed.

Copyright
Corresponding author
*Corresponding author. E-mail: markvandewouw@yahoo.co.uk
References
Hide All
Allard RW (1996) Genetic basis of the evolution of adaptedness in plants. Euphytica 92: 111.
Almanza-Pinzon MI, Khairallah M, Fox PN and Warburton ML (2003) Comparison of molecular markers and coefficients of parentage for the analysis of genetic diversity among spring bread wheat accessions. Euphytica 130: 7786.
Bardsley D and Thomas I (2005) Valuing local wheat landraces for agrobiodiversity conservation in Northeast Turkey. Agriculture Ecosystems & Environment 106: 407412.
Barry MB, Pham JL, Beavogui S, Ghesquiere A and Ahmadi N (2008) Diachronic (1979–2003) analysis of rice genetic diversity in Guinea did not reveal genetic erosion. Genetic Resources and Crop Evolution 55: 723733.
Baur E (1914) Die Bedeutung der primitiven Kulturrassen und der wilden Verwandten unserer Kulturpflanzen für die Pflanzenzüchtung. Jahrbuch der Deutschen Landwirtschafts Gesellschaft 29: 104110.
Bennett E (1973) Wheats of the Mediterranean basin. In: Frankel OH (ed.) Survey of Crop Genetic Resources in Their Centre of Diversity. First Report: FAO – IBP, pp. 18.
Bitocchi E, Nanni L, Rossi M, Rau D, Bellucci E, Giardini A, Buonamici A, Vendramin GG and Papa R (2009) Introgression from modern hybrid varieties into landrace populations of maize (Zea mays ssp. mays L.) in central Italy. Molecular Ecology 18: 603621.
Boches P, Bassil NV and Rowland L (2006) Genetic diversity in the highbush blueberry evaluated with microsatellite markers. Journal of the American Society for Horticultural Science 131: 674686.
Bonifacio A (2003) Chenopodium sp.: genetic resources, ethnobotany, and geographic distribution. Food Reviews International 19: 17.
Brennan JP and Fox PN (1998) Impact of CIMMYT varieties on the genetic diversity of wheat in Australia, 1973–1993. Australian Journal of Agricultural Research 49: 175178.
Brinckmann J and Smith E (2004) Maca culture of the Junin plateau. Journal of Alternative and Complementary Medicine 10: 426430.
Brush S, Kesseli R, Ortega R, Cisneros P, Zimmerer K and Quiros C (1995) Potato diversity in the Andean center of crop domestication. Conservation Biology 9: 11891198.
Buckler ES, Thornsberry JM and Kresovich S (2001) Molecular diversity, structure and domestication of grasses. Genetical Research 77: 213218.
Buerkert A, Oryakhail M, Filatenko AA and Hammer K (2006) Cultivation and taxonomic classification of wheat landraces in the upper Panjsher valley of Afghanistan after 23 years of war. Genetic Resources and Crop Evolution 53: 9197.
Caicedo AL, Williamson SH, Hernandez RD, Boyko A, Fledel-Alon A, York TL, Polato NR, Olsen KM, Nielsen R, McCouch SR, Bustamante CD and Purugganan MD (2007) Genome-wide patterns of nucleotide polymorphism in domesticated rice. PLos Genetics 3: 17451756.
Christiansen MJ, Andersen SB and Ortiz R (2002) Diversity changes in an intensively bred wheat germplasm during the 20th century. Molecular Breeding 9: 111.
Clark RM, Linton E, Messing J and Doebley JF (2004) Pattern of diversity in the genomic region near the maize domestication gene tb1. Proceedings of the National Academy of Sciences of the United States of America 101: 700707.
Dawe D (2003) The monoculture myth. Rice Today 2: 33.
Dobrotvorskaya TV, Martynov SP and Pukhalskyi VA (2004) Trends in genetic diversity change of spring bread wheat cultivars released in Russia in 1929–2003. Russian Journal of Genetics 40: 12451257.
Doebley JF, Gaut BS and Smith BD (2006) The molecular genetics of crop domestication. Cell 127: 13091321.
Ellstrand NC and Elam DR (1993) Population genetic consequences of small population size – implications for plant conservation. Annual Review of Ecology and Systematics 24: 217242.
Erskine W, Chandra S, Chaudhry M, Malik IA, Sarker A, Sharma B, Tufail M and Tyagi MC (1998) A bottleneck in lentil: widening its genetic base in south Asia. Euphytica 101: 207211.
Evenson RE (2003) Production impacts of crop genetic improvement. In: Evenson RE and Gollin D (eds) Crop Variety Improvement and Its Effect on Productivity, The Impact of International Agricultural Research. Wallingford: CABI publishing, pp. 447471.
Ford-Lloyd BV (2006) Realistic population and molecular genetic approaches to genetic assessment. In: Ford-Lloyd BV, Dias SR and Bettencourt E (eds) Genetic Erosion and Pollution Assessment Methodologies. Proceedings of PGR Forum Workshop 5, Terceira Island, Autonomous Region of the Azores, Portugal, 8–11 September 2004. Rome: Bioversity International, pp. 5154.
Fowler C and Mooney P (1990) Shattering: Food, Politics, and The Loss of Genetic Diversity. Tucson: The University of Arizona Press.
Frankel OH and Bennett E (1970) Genetic Resources – Introduction. In: Frankel OH and Bennett E (eds) Genetic Resources in Plants – Their Exploration and Conservation, IPB Handbook No. 11. London: International Biological Programme, pp. 718.
Fraser EDG (2003) Social vulnerability and ecological fragility: building bridges between social and natural sciences using the Irish Potato Famine as a case study. Conservation Ecology: 7.
Fu YB, Diederichsen A, Richards KW and Peterson G (2002) Genetic diversity within a range of cultivars and landraces of flax (Linum usitatissimum L.) as revealed by RAPDs. Genetic Resources and Crop Evolution 49: 167174.
Fu YB, Peterson GW, Scoles G, Rossnagel B, Schoen DJ and Richards KW (2003) Allelic diversity changes in 96 Canadian oat cultivars released from 1886 to 2001. Crop Science 43: 19891995.
Fu YB, Peterson GW, Richards KW, Somers D, DePauw RM and Clarke JM (2005) Allelic reduction and genetic shift in the Canadian hard red spring wheat germplasm released from 1845 to 2004. Theoretical and Applied Genetics 110: 15051516.
Fu YB, Peterson GW, Yu JK, Gao LF, Jia JZ and Richards KW (2006) Impact of plant breeding on genetic diversity of the Canadian hard red spring wheat germplasm as revealed by EST-derived SSR markers. Theoretical and Applied Genetics 112: 12391247.
Fu YB, Peterson GW and Morrison MJ (2007) Genetic diversity of Canadian soybean cultivars and exotic germplasm revealed by simple sequence repeat markers. Crop Science 47: 19471954.
Gao LZ (2003) The conservation of Chinese rice biodiversity: genetic erosion, ethnobotany and prospects. Genetic Resources and Crop Evolution 50: 1732.
Gepts P (2006) Plant genetic resources conservation and utilization: the accomplishments and future of a societal insurance policy. Crop Science 46: 22782292.
Hammer K and Khoshbakht K (2005) Towards a ’red list’ for crop plant species. Genetic Resources and Crop Evolution 52: 249265.
Hammer K and Laghetti G (2005) Genetic erosion – examples from Italy. Genetic Resources and Crop Evolution 52: 629634.
Hammer K, Knupffer H, Xhuveli L and Perrino P (1996) Estimating genetic erosion in landraces – two case studies. Genetic Resources and Crop Evolution 43: 329336.
Hao C, Wang L, Zhang X, You G, Dong Y, Jia J, Liu X, Shang X, Liu S and Cao Y (2006a) Genetic diversity in Chinese modern wheat varieties revealed by microsatellite markers. Science in China, Series C: Life Sciences 49: 218226.
Hao CY, Zhang XY, Wang LF, Dong YS, Shang XW and Jia JZ (2006b) Genetic diversity and core collection evaluations in common wheat germplasm from the Northwestern Spring Wheat Region in China. Molecular Breeding 17: 6977.
Harlan JR (1970) Evolution of cultivated plants. In: Frankel OH and Bennett E (eds) Genetic Resources in Plants – IBP Handbook No 11. London: International Biological Programme, pp. 1932.
Harlan JR (1975) Our vanishing genetic resources. Science 188: 618621.
Harlan JR and de Wet JMJ (1971) Toward a rational classification of cultivated plants. Taxon 20: 509517.
Heal G, Walker B, Levin S, Arrow K, Dasgupta P, Daily G, Ehrlich P, Maler KG, Kautsky N, Lubchenco J, Schneider S and Starrett D (2004) Genetic diversity and interdependent crop choices in agriculture. Resource and Energy Economics 26: 175184.
Hernandez-Verdugo S, Luna-Reyes R and Oyama K (2001) Genetic structure and differentiation of wild and domesticated populations of Capsicum annuum (Solanaceae) from Mexico. Plant Systematics and Evolution 226: 129142.
Huang XQ, Wolf M, Ganal MW, Orford S, Koebner RMD and Roder MS (2007) Did modern plant breeding lead to genetic erosion in European winter wheat varieties? Crop Science 47: 343349.
Hyten DL, Song QJ, Zhu YL, Choi IY, Nelson RL, Costa JM, Specht JE, Shoemaker RC and Cregan PB (2006) Impacts of genetic bottlenecks on soybean genome diversity. Proceedings of the National Academy of Sciences of the United States of America 103: 1666616671.
IPGRI (2002) Neglected and Unterutilized Plant Species: Strategic Action Plan of the International Plant Genetic Resources Institute. Rome: International Plant Genetic Resources Institute.
Ishikawa R, Yamanaka S, Fukuta Y, Chitrakon S, Bounphanousay C, Kanyavong K, Tang LH, Nakamura I, Sato T and Sato YI (2006) Genetic erosion from modern varieties into traditional upland rice cultivars (Oryza sativa L.) in northern Thailand. Genetic Resources and Crop Evolution 53: 245252.
Jana S and Pietrzak LN (1988) Comparative assessment of genetic diversity in wild and primitive cultivated barley in a center of diversity. Genetics 119: 981990.
Jarvis DI and Hodgkin T (1999) Wild relatives and crop cultivars: detecting natural introgression and farmer selection of new genetic combinations in agroecosystems. Molecular Ecology 8: S159S173.
Jordan DR, Tao YZ, Godwin ID, Henzell RG, Cooper M and McIntyre CL (1998) Loss of genetic diversity associated with selection for resistance to sorghum midge in Australian sorghum. Euphytica 102: 17.
Jusu MS (1999) Management of genetic variability in rice (Oryza sativa L. and O. glaberrima Steud.) by breeders and farmers in Sierra Leone. Wageningen: Wageningen Universiteit, p. 198.
Kebebew F, Tsehaye Y and McNeilly T (2001) Diversity of durum wheat (Triticum durum Desf.) at in situ conservation sites in North Shewa and Bale, Ethiopia. Journal of Agricultural Science 136: 383392.
Khlestkina EK, Huang XQ, Quenum FJB, Chebotar S, Roder MS and Borner A (2004) Genetic diversity in cultivated plants – loss or stability? Theoretical and Applied Genetics 108: 14661472.
Kik C, Samoylov AM, Verbeek WHJ, Van Raamsdonk LWD and Mitochondrial DNA (1997) variation and crossability of leek (Allium porrum) and its wild relatives from the Allium ampeloprasum complex. Theoretical and Applied Genetics 94: 465471.
Kochert G, Stalker HT, Gimenes M, Galgaro L, Lopes CR and Moore K (1996) RFLP and cytogenetic evidence on the origin and evolution of allotetraploid domesticated peanut, Arachis hypogaea (Leguminosae). American Journal of Botany 83: 12821291.
Kolodinska Brantestam A, von Bothmer R, Dayteg C, Rashal I, Tuvesson S and Weibull J (2004) Inter simple sequence repeat analysis of genetic diversity and relationships in cultivated barley of Nordic and Baltic origin. Hereditas 141: 186192.
Kurosaki T (2003) Specialization and diversification in agricultural transformation: the case of West Punjab,1903–92. American Journal of Agricultural Economics 85: 372386.
Landis DA, Gardiner MM, van der Werf W and Swinton SM (2008) Increasing corn for biofuel production reduces biocontrol in agricultural landscapes. Proceedings of the National Academy of Sciences of the United States of America 105: 2055220557.
Le Clerc V, Cadot V, Canadas M, Lallemand J, Guerin D and Boulineau F (2006) Indicators to assess temporal genetic diversity in the French Catalogue: no losses for maize and peas. Theoretical and Applied Genetics 113: 11971209.
Lelley T, Stachel M, Grausgruber H and Vollmann J (2000) Analysis of relationships between Aegilops tauschii and the D genome of wheat utilizing microsatellites. Genome 43: 661668.
Levings CS (1990) The Texas cytoplasm of maize: cytoplasmic male sterility and disease susceptibility. Science 250: 942947.
Lopez PB (1994) A new plant disease: uniformity. CERES 26: 4147.
Louette D and Smale M (2000) Farmers' seed selection practices and traditional maize varieties in Cuzalapa, Mexico. Euphytica 113: 2541.
Malysheva-Otto L, Ganal MW, Law JR, Reeves JC and Roder MS (2007) Temporal trends of genetic diversity in European barley cultivars (Hordeum vulgare L.). Molecular Breeding 20: 309322.
Manifesto MM, Schlatter AR, Hopp HE, Suarez EY and Dubcovsky J (2001) Quantitative evaluation of genetic diversity in wheat germplasm using molecular markers. Crop Science 41: 682690.
Maredia MK, Byerlee D and Pee P (2000) Impacts of food crop improvement research: evidence from sub-Saharan Africa. Food Policy 25: 531559.
Martos V, Royo C, Rharrabti Y and del Moral LFG (2005) Using AFLPs to determine phylogenetic relationships and genetic erosion in durum wheat cultivars released in Italy and Spain throughout the 20th century. Field Crops Research 91: 107116.
Martynov SP, Dobrotvorskaya TV and Pukhalskiy VA (2005) Analysis of genetic diversity of spring durum wheat (Triticum durum Desf.) cultivars released in Russia in 1929–2004. Russian Journal of Genetics 41: 11131122.
Martynov SP, Dobrotvorskaya TV and Pukhalskiy VA (2006) Dynamics of genetic diversity in winter common wheat Triticum aestivum L. cultivars released in Russia from 1929 to 2005. Russian Journal of Genetics 42: 11371147.
Maughan PJ, Saghai Maroof MA, Buss GR and Huestis GM (1996) Amplified fragment length polymorphism (AFLP) in soybean: species diversity, inheritance, and near-isogenic line analysis. Theoretical and Applied Genetics 93: 392401.
Nabhan GP (2007) Agrobiodiversity change in a Saharan desert oasis, 1919–2006: historic shifts in Tasiwit (Berber) and Bedouin crop inventories of Siwa, Egypt. Economic Botany 61: 3143.
Negash A, Tsegaye A, van Treuren R and Visser B (2002) AFLP analysis of enset clonal diversity in south and southwestern Ethiopia for conservation. Crop Science 42: 11051111.
Nei M (1973) Analysis of gene diversity in subdivided populations. Proceedings of the National Academy of Sciences of the United States of America 70: 33213323.
Nersting LG, Andersen SB, von Bothmer R, Gullord M and Jorgensen RB (2006) Morphological and molecular diversity of Nordic oat through one hundred years of breeding. Euphytica 150: 327337.
Ochoa C (1975) Potato collecting expeditions in Chile, Bolivia and Peru, and the genetic erosion of indigenous cultivars. In: Frankel OH and Hawkes JG (eds) Crop Genetic Resources for Today and Tomorrow. Cambridge: Cambridge University Press, pp. 167173.
Olsen KM and Purugganan MD (2002) Molecular evidence on the origin and evolution of glutinous rice. Genetics 162: 941950.
Palaisa K, Morgante M, Tingey S and Rafalski A (2004) Long-range patterns of diversity and linkage disequilibrium surrounding the maize Y1 gene are indicative of an asymmetric selective sweep. Proceedings of the National Academy of Sciences of the United States of America 101: 98859890.
Palladino P (1990) The political economy of applied research: plant breeding in Great Britain, 1910–1940. Minerva 28: 446468.
Parzies HK, Spoor W and Ennos RA (2000) Genetic diversity of barley landrace accessions (Hordeum vulgare ssp vulgare) conserved for different lengths of time in ex situ gene banks. Heredity 84: 476486.
Peng JR, Richards DE, Hartley NM, Murphy GP, Devos KM, Flintham JE, Beales J, Fish LJ, Worland AJ, Pelica F, Sudhakar D, Christou P, Snape JW, Gale MD and Harberd NP (1999) ‘Green revolution’ genes encode mutant gibberellin response modulators. Nature 400: 256261.
Peroni N and Hanazaki N (2002) Current and lost diversity of cultivated varieties, especially cassava, under swidden cultivation systems in the Brazilian Atlantic Forest. Agriculture Ecosystems & Environment 92: 171183.
Pistorius R (1997) Scientists, Plants and Politics – A History of The Plant Genetic Resources Movement. Rome: International Plant Genetic Resources Institute.
Portis E, Acquadro A, Comino C and Lanteri S (2004) Effect of farmers' seed selection on genetic variation of a landrace population of pepper (Capsicum annuum L.), grown in North-West Italy. Genetic Resources and Crop Evolution 51: 581590.
Prashanth SR, Parani M, Mohanty BP, Talame V, Tuberosa R and Parida A (2002) Genetic diversity in cultivars and landraces of Oryza sativa subsp indica as revealed by AFLP markers. Genome 45: 451459.
Pressoir G and Berthaud J (2004) Patterns of population structure in maize landraces from the Central Valleys of Oaxaca in Mexico. Heredity 92: 8894.
Purseglove JW (1974) Tropical Crops, Dicotyledons. Harlow: Longman.
Qi Y, Zhang D, Zhang H, Wang M, Sun J, Wei X, Qiu Z, Tang S, Cao Y, Wang X and Li Z (2006) Genetic diversity of rice cultivars (Oryza sativa L.) in China and the temporal trends in recent fifty years. Chinese Science Bulletin 51: 681688.
Rasmusson DC and Phillips RL (1997) Plant breeding progress and genetic diversity from de novo variation and elevated epistasis. Crop Science 37: 303310.
Reif JC, Hamrit S, Heckenberger M, Schipprack W, Maurer HP, Bohn M and Melchinger AE (2005a) Trends in genetic diversity among European maize cultivars and their parental components during the past 50 years. Theoretical and Applied Genetics 111: 838845.
Reif JC, Zhang P, Dreisigacker S, Warburton ML, van Ginkel M, Hoisington D, Bohn M and Melchinger AE (2005b) Wheat genetic diversity trends during domestication and breeding. Theoretical and Applied Genetics 110: 859864.
Richards R and Ruivenkamp G (1997) Seeds and Survival: Crop Genetic Resources in War and Reconstruction in Africa. Rome: International Plant Genetic Resources Institute.
Roussel V, Koenig J, Beckert M and Balfourier F (2004) Molecular diversity in French bread wheat accessions related to temporal trends and breeding programmes. Theoretical and Applied Genetics 108: 920930.
Roussel V, Leisova L, Exbrayat F, Stehno Z and Balfourier F (2005) SSR allelic diversity changes in 480 European bread wheat varieties released from 1840 to 2000. Theoretical and Applied Genetics 111: 162170.
Scholten M, Maxted N and Ford-Lloyd BV (2006) UK National Inventory of Plant Genetic Resources for Food and Agriculture. Birmingham: School of Biosciences, University of Birmingham, p. 86.
Smale M (1997) The green revolution and wheat genetic diversity: Some unfounded assumptions. World Development 25: 12571269.
Smale M, Reynolds MP, Warburton M, Skovmand B, Trethowan R, Singh RP, Ortiz-Monasterio I and Crossa J (2002) Dimensions of diversity in modern spring bread wheat in developing countries from 1965. Crop Science 42: 17661779.
Soleimani VD, Baum BR and Johnson DA (2002) AFLP and pedigree-based genetic diversity estimates in modern cultivars of durum wheat (Triticum turgidum L. subsp durum (Desf.) Husn.). Theoretical and Applied Genetics 104: 350357.
Souza E and Sorrells ME (1989) Pedigree analysis of North-American oat cultivars released from 1951 to 1985. Crop Science 29: 595601.
Sperling L (2001) The effect of the civil war on Rwanda's bean seed systems and unusual bean diversity. Biodiversity and Conservation 10: 9891009.
Tanksley SD and McCouch SR (1997) Seed banks and molecular maps: unlocking genetic potential from the wild. Science 277: 10631066.
Tenaillon MI, U'Ren J, Tenaillon O and Gaut BS (2004) Selection versus demography: A multilocus investigation of the domestication process in maize. Molecular Biology and Evolution 21: 12141225.
Theissen G (2002) Key genes of crop domestication and breeding: molecular analyses. Pogress in Botany 63: 189203.
Thomson MJ, Septiningsih EM, Suwardjo F, Santoso TJ, Silitonga TS and McCouch SR (2007) Genetic diversity analysis of traditional and improved Indonesian rice (Oryza sativa L.) germplasm using microsatellite markers. Theoretical and Applied Genetics 114: 559568.
Tian QZ, Zhou RH and Jia JZ (2005) Genetic diversity trend of common wheat (Triticum aestivum L.) in China revealed with AFLP markers. Genetic Resources and Crop Evolution 52: 325331.
Tsegaye B and Berg T (2007) Genetic erosion of Ethiopian tetraploid wheat landraces in Eastern Shewa, Central Ethiopia. Genetic Resources and Crop Evolution 54: 715726.
van Zanden JL (1991) The first green revolution: the growth of production and productivity in European agriculture, 1870–1914. The Economic History Review 44: 215239.
van de Wouw M, van Hintum T, Kik C, van Treuren R and Visser B (submitted) Genetic diversity trends in 20th century crop cultivars- a meta analysis. Theoretical and Applied Genetics.
van der Meer WC and van den Ban PA (1956) Bijzondere plantenteelt. Zwolle: Tjeenk Willink.
Warburton ML, Crossa J, Franco J, Kazi M, Trethowan R, Rajaram S, Pfeiffer W, Zhang P, Dreisigacker S and van Ginkel M (2006) Bringing wild relatives back into the family: recovering genetic diversity in CIMMYT improved wheat germplasm. Euphytica 149: 289301.
White J, Law JR, MacKay I, Chalmers KJ, Smith JSC, Kilian A and Powell W (2008) The genetic diversity of UK, US and Australian cultivars of Triticum aestivum measured by DArT markers and considered by genome. Theoretical and Applied Genetics 116: 439453.
Willemen L, Scheldeman X, Cabellos VS, Salazar SR and Guarino L (2007) Spatial patterns of diversity and genetic erosion of traditional cassava (Manihot esculenta Crantz) in the Peruvian Amazon: An evaluation of socio-economic and environmental indicators. Genetic Resources and Crop Evolution 54: 15991612.
Yang GP, Maroof MAS, Xu CG, Zhang QF and Biyashev RM (1994) Comparative-analysis of aicrosatellite DNA polymorphism in landraces and cultivars of rice. Molecular & General Genetics 245: 187194.
Zeder MA, Emshwiller E, Smith BD and Bradley DG (2006) Documenting domestication: the intersection of genetics and archaeology. Trends in Genetics 22: 139155.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Plant Genetic Resources
  • ISSN: 1479-2621
  • EISSN: 1479-263X
  • URL: /core/journals/plant-genetic-resources
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
×

Keywords:

Metrics

Full text views

Total number of HTML views: 22
Total number of PDF views: 157 *
Loading metrics...

Abstract views

Total abstract views: 1060 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 17th December 2017. This data will be updated every 24 hours.