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Network simulations to study seed exchange for agrobiodiversity conservation

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Abstract

Crop diversity is essential for sustainable development because diverse crops cope better with disease and climate change. A way to maintain crop diversity is to sustain seed exchange among farmers. Network simulations help in establishing which network properties promote crop diversity conservation. Here, we modelled the likelihood that an introduced crop variety will spread in a seed exchange network. The network model is based on published data on a directed network of barley seed flows in seven villages of Northern Ethiopia. Results show that the number of households that can be reached when introducing a new variety depends on the number of outgoing links of the household that first received the new variety. The distribution of the number of both incoming and outgoing links shows a departure from a normal distribution. This trend is explained by the presence of a minority of highly connected households and of a majority of weakly connected households. For the whole network, there is no significant correlation between the number of incoming and outgoing links of households. The findings explain the common observation that individual farmers do not cultivate all varieties present in a seed system. Absence of reciprocal exchange makes such networks less vulnerable to wholesale displacement of farmer varieties by improved ones.

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References

  • Abay F, de Boef W, Bjørnstad Å (2011) Network analysis of barley seed flows in Tigray, Ethiopia: supporting the design of strategies that contribute to on-farm management of plant genetic resources. Plant Genet Res 9:495–505. doi:10.1017/S1479262111000773

    Article  Google Scholar 

  • Abebe TD, Bauer AM, Léon J (2010) Morphological diversity of Ethiopian barleys (Hordeum vulgare L.) in relation to geographic regions and altitudes. Hereditas 147:154–164. doi:10.1111/j.1601-5223.2010.02173.x

    Article  PubMed  Google Scholar 

  • Abebe TD, Mathew B, Léon J (2013) Barrier analysis detected genetic discontinuity among Ethiopian barley (Hordeum vulgare L.) landraces due to landscape and human mobility on gene flow. Genet Resour Crop Evol 60:297–309. doi:10.1007/s10722-012-9834-6

    Article  Google Scholar 

  • Almekinders CJM, Louwaars NP, Bruijn GH (1994) Local seed systems and their importance for an improved seed supply in developing countries. Euphytica 78:207–216. doi:10.1007/BF00027519

    Article  Google Scholar 

  • Aw-Hassan A, Mazid A, Salahieh H (2008) The role of informal farmer-to-farmer seed distribution in the diffusion of new barley varieties in Syria. Exp Agric 44:413–431. doi:10.1017/S001447970800642X

    Article  Google Scholar 

  • Bajracharya J, Brown AHD, Joshi BK, Panday D, Baniya BK, Sthapit BR, Jarvis DI (2012) Traditional seed management and genetic diversity in barley varieties in high-hill agro-ecosystems of Nepal. Genet Resour Crop Evol 59:389–398. doi:10.1007/s10722-011-9689-2

    Article  Google Scholar 

  • Bellon MR, Hodson D, Hellin J (2011) Assessing the vulnerability of traditional maize seed systems in Mexico to climate change. Proc Natl Acad Sci U S A 108:13432–13437. doi:10.1073/pnas.1103373108

    Article  CAS  PubMed Central  PubMed  Google Scholar 

  • Bjørnstad A, Abay F (2010) Multivariate patterns of diversity in Ethiopian barleys. Crop Sci 50:1579–1586. doi:10.2135/cropsci2009.12.0719

    Article  Google Scholar 

  • Calvet-Mir L, Calvet-Mir M, Luis Molina J, Reyes-García V (2012) Seed exchange as an agrobiodiversity conservation mechanism. A case study in Vall Fosca, Catalan Pyrenees, Iberian Peninsula. Ecol Soc 17:29

    Google Scholar 

  • Cavatassi R, Lipper L, Narloch U (2011) Modern variety adoption and risk management in drought prone areas: insights from the sorghum farmers of eastern Ethiopia. Agric Econ 42:279–292. doi:10.1111/j.1574-0862.2010.00514.x

    Article  Google Scholar 

  • Chadès I, Martin TG, Nicol S, Burgman MA, Possingham HP, Buckley YM (2011) General rules for managing and surveying networks of pests, diseases, and endangered species. Proc Natl Acad Sci U S A 108:8323–8328. doi:10.1073/pnas.1016846108

    Article  PubMed Central  PubMed  Google Scholar 

  • Chakrabarti D, Wang Y, Wang C, Leskovec J, Faloutsos C (2008) Epidemic thresholds in real networks. ACM Trans Info Syst Secur 10:1–26. doi:10.1145/1284680.1284681

    Article  Google Scholar 

  • de Boef WS, Dempewolf H, Byakweli JM, Engels JMM (2010) Integrating genetic resource conservation and sustainable development into strategies to increase the robustness of seed systems. J Sust Agric 34:504–531. doi:10.1080/10440046.2010.484689

    Article  Google Scholar 

  • Delaunay S, Tescar R-P, Oualbego A, vom Brocke K, Lançon J (2009) La culture du coton ne bouleverse pas les échanges traditionnels de semences de sorgho. Cah Agric 17:189–194

    Google Scholar 

  • Döring TF, Vieweger A, Pautasso M, Vaarst M, Finckh MR, Wolfe MS (2014) Resilience as a universal criterion of health. J Sci Food Agric. doi:10.1002/jsfa.6539

    Google Scholar 

  • Dyer GA, González C, Lopera DC (2011) Informal “seed” systems and the management of gene flow in traditional agroecosystems: the case of cassava in Cauca, Colombia. PLoS One 6:e29067. doi:10.1371/journal.pone.0029067

    Article  CAS  PubMed Central  PubMed  Google Scholar 

  • Fuentes FF, Bazile D, Bhargava A, Martinez EA (2012) Implications of farmers’ seed exchanges for on-farm conservation of quinoa, as revealed by its genetic diversity in Chile. J Agric Sci 150:702–716. doi:10.1017/S0021859612000056

    Article  Google Scholar 

  • Gildemacher PR, Demo P, Barker I, Kaguongo W, Woldegiorgis G, Wagoire WW, Wakahiu M, Leeuwis C, Struik PC (2009) A description of seed potato systems in Kenya, Uganda and Ethiopia. Am J Potato Res 86:373–382. doi:10.1007/s12230-009-9092-0

    Article  Google Scholar 

  • Hodgkin T, Rana R, Tuxill J, Balma D, Subedi A, Mar I, Karamura D, Valdivia R, Collado L, Latournerie L, Sadiki M, Sawadogo M, Brown AHD, Jarvis DI (2007) Seed systems and crop genetic diversity in agroecosystems. In: Jarvis DI, Padoch C, Cooper HD (eds) Managing biodiversity in agricultural systems. Columbia University Press, New York, pp 77–116

    Google Scholar 

  • Jarvis DI, Hodgkin T, Sthapit BR, Fadda C, Lopez-Noriega I (2011) An heuristic framework for identifying multiple ways of supporting the conservation and use of traditional crop varieties within the agricultural production system. Crit Rev Plant Sci 30:125–176. doi:10.1080/07352689.2011.554358

    Article  Google Scholar 

  • Jeger MJ, Pautasso M, Holdenrieder O, Shaw MW (2007) Modelling disease spread and control in networks: implications for plant sciences. New Phytol 174:279–297. doi:10.1111/j.1469-8137.2007.02028.x

    Article  PubMed  Google Scholar 

  • Jensen HR, Belqadi L, De Santis P, Sadiki M, Jarvis DI, Schoen DJ (2013) A case study of seed exchange networks and gene flow for barley (Hordeum vulgare subsp. vulgare) in Morocco. Genet Resour Crop Evol 60:1119–1138. doi:10.1007/s10722-012-9909-4

    Article  Google Scholar 

  • Johnson JC, Christian RR, Brunt JW, Hickman CR, Waide RB (2010) Evolution of collaboration within the US Long Term Ecological Research Network. Bioscience 60:931–940. doi:10.1525/bio.2010.60.11.9

    Article  Google Scholar 

  • Kawa NC, McCarty C, Clement CR (2013) Manioc varietal diversity, social networks, and distribution constraints in rural Amazonia. Curr Anthropol 54:764–770

    Article  Google Scholar 

  • Labeyrie V, Rono B, Leclerc C (2014) How social organization shapes crop diversity: an ecological anthropology approach among Tharaka farmers of Mount Kenya. Agric Hum Values 31:97–107. doi:10.1007/s10460-013-9451-9

    Article  Google Scholar 

  • Leclerc C, Coppens d’Eeckenbrugge G (2012) Social organization of crop genetic diversity. The G × E × S interaction model. Diversity 4:1–32. doi:10.3390/d4010001

    Article  Google Scholar 

  • Lindström T, Grear DA, Buhnerkempe M, Webb CT, Miller RS, Portacci K, Wennergren U (2013) A Bayesian approach for modeling cattle movements in the United States: scaling up a partially observed network. PLoS One 8:e53432. doi:10.1371/journal.pone.0053432

    Article  PubMed Central  PubMed  Google Scholar 

  • Louwaars NP, de Boef WS (2012) Integrated seed sector development in Africa: a conceptual framework for creating coherence between practices, programs, and policies. J Crop Improv 26:39–59. doi:10.1080/15427528.2011.611277

    Article  Google Scholar 

  • Marfo KA, Dorward PT, Craufurd PQ, Ansere-Bioh F, Haleegoah J, Bam R (2008) Identifying seed uptake pathways: the spread of Agya amoah rice cultivar in southwestern Ghana. Exp Agric 44:257–269. doi:10.1017/S0014479708006170

    Article  Google Scholar 

  • May RM (2006) Network structure and the biology of populations. Trends Ecol Evol 21:394–399. doi:10.1016/j.tree.2006.03.013

    Article  PubMed  Google Scholar 

  • Moslonka-Lefebvre M, Pautasso M, Jeger MJ (2009) Disease spread in small-size directed networks: epidemic threshold, correlation between links to and from nodes, and clustering. J Theor Biol 260:402–411. doi:10.1016/j.jtbi.2009.06.015

    Article  PubMed  Google Scholar 

  • Moslonka-Lefebvre M, Finley A, Dorigatti I, Dehnen-Schmutz K, Harwood T, Jeger MJ, Xu XM, Holdenrieder O, Pautasso M (2011) Networks in plant epidemiology: from genes to landscapes, countries and continents. Phytopathology 101:392–403. doi:10.1094/PHYTO-07-10-0192

    Article  PubMed  Google Scholar 

  • Moslonka-Lefebvre M, Harwood T, Jeger MJ, Pautasso M (2012) SIS along a continuum (SISc) epidemiological modelling and control of diseases on directed trade networks. Math Biosci 236:44–52. doi:10.1016/j.mbs.2012.01.004

    Article  PubMed  Google Scholar 

  • Pautasso M, Jeger MJ (2008) Epidemic threshold and network structure: the interplay of probability of transmission and of persistence in directed networks. Ecol Compl 5:1–8. doi:10.1016/j.ecocom.2007.07.001

    Article  Google Scholar 

  • Pautasso M, Jeger MJ (2014) Network epidemiology and plant trade networks. AoB Plants. doi:10.1093/aobpla/plu007

    PubMed Central  PubMed  Google Scholar 

  • Pautasso M, Moslonka-Lefebvre M, Jeger MJ (2010a) The number of links to and from the starting node as a predictor of epidemic size in small-size directed networks. Ecol Compl 7:424–432. doi:10.1016/j.ecocom.2009.10.003

    Article  Google Scholar 

  • Pautasso M, Xu XM, Jeger MJ, Harwood TD, Moslonka-Lefebvre M, Pellis L (2010b) Disease spread in small-size directed trade networks: the role of hierarchical categories. J Appl Ecol 47:1300–1309. doi:10.1111/j.1365-2664.2010.01884.x

    Article  Google Scholar 

  • Pautasso M, Aistara G, Barnaud A, Caillon S, Clouvel P, Coomes OT, Delêtre M, Demeulenaere E, De Santis P, Döring T, Eloy L, Emperaire L, Garine E, Goldringer I, Jarvis D, Joly HI, Leclerc C, Louafi S, Martin P, Massol F, McGuire S, McKey D, Padoch C, Soler C, Thomas M, Tramontini S (2013) Seed exchange networks for agrobiodiversity conservation. A review. Agron Sustain Dev 33:151–175. doi:10.1007/s13593-012-0089-6

    Article  Google Scholar 

  • Portis E, Baudino M, Magurno F, Lanteri S (2012) Genetic structure and preservation strategies of autochthonous vegetable crop landraces of north-western Italy. Ann Appl Biol 160:76–85. doi:10.1111/j.1744-7348.2011.00522.x

    Article  Google Scholar 

  • Rana RB, Garforth C, Sthapit B, Jarvis D (2007) Influence of socio-economic and cultural factors in rice varietal diversity management on-farm in Nepal. Agric Hum Values 24:461–472. doi:10.1007/s10460-007-9082-0

    Article  Google Scholar 

  • Ruiz KB, Biondi S, Oses R, Acuña-Rodríguez IS, Antognoni F, Martinez-Mosqueira EA, Coulibaly A, Canahua-Murillo A, Pinto M, Zurita-Silva A, Bazile D, Jacobsen S-E, Molina-Montenegro MA (2014) Quinoa biodiversity and sustainability for food security under climate change. A review. Agric Sustain Dev. doi:10.1007/s13593-013-0195-0

    Google Scholar 

  • Samberg LH, Fishman L, Allendorf FW (2013) Population genetic structure in a social landscape: barley in a traditional Ethiopian agricultural system. Evol Appl 6:1133–1145. doi:10.1111/eva.12091

    Article  PubMed Central  PubMed  Google Scholar 

  • Stromberg PM, Pascual U, Bellon MR (2010) Seed systems and farmers’ seed choices: the case of maize in the Peruvian Amazon. Hum Ecol 38:539–553. doi:10.1007/s10745-010-9333-3

    Article  Google Scholar 

  • Stumpf MPH, Wiuf C, May RM (2005) Subnets of scale-free networks are not scale-free: sampling properties of networks. Proc Natl Acad Sci U S A 102:4221–4224. doi:10.1073/pnas.0501179102

    Article  CAS  PubMed Central  PubMed  Google Scholar 

  • Subedi A, Chaudhary P, Baniya BK, Rana RB, Tiwari RK, Rijal DK, Sthapit BR, Jarvis DI (2003) Who maintains crop genetic diversity and how?: implications for on-farm conservation and utilization. Cult Agric 25:41–50. doi:10.1525/cag.2003.25.2.41

    Article  Google Scholar 

  • Thomas M, Dawson JC, Goldringer I, Bonneuil C (2011) Seed exchanges, a key to analyze crop diversity dynamics in farmer-led on-farm conservation. Genet Resour Crop Evol 58:321–338. doi:10.1007/s10722-011-9662-0

    Article  Google Scholar 

  • van Leur JAG, Gebre H (2003) Diversity between some Ethiopian farmer's varieties of barley and within these varieties among seed sources. Genet Resour Crop Evol 50:351–357. doi:10.1023/A:1023966702389

    Article  Google Scholar 

  • Watts DJ, Strogatz SH (1998) Collective dynamics of ‘small-world’ networks. Nature 393:440–442. doi:10.1038/30918

    Article  CAS  PubMed  Google Scholar 

  • Woolhouse MEJ, Shaw DJ, Matthews L, Liu WC, Mellor DJ, Thomas MR (2005) Epidemiological implications of the contact network structure for cattle farms and the 20–80 rule. Biol Lett 1:350–352. doi:10.1098/rsbl.2005.0331

    Article  CAS  PubMed Central  PubMed  Google Scholar 

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Acknowledgments

Many thanks to F. Abay, W. de Boef and Å. Bjørnstad for making their network available in Abay et al. (2011) for further analysis; to O. Holdenrieder, M. Jeger, H. Joly, F. Laso, M. Moslonka-Lefebvre, C. Soler and the participants of the Netseed research project for insights and discussions; to E. Lichtfouse, T. Matoni and anonymous reviewers for helpful comments on a previous draft; and to the French Foundation for Research on Biodiversity (FRB) for supporting this work through its Centre for Synthesis and Analysis of Biodiversity (CESAB).

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  1. Forest Pathology and Dendrology, Swiss Federal Institute of Technology, ETH Zurich, Zurich, 8092, Switzerland

    Marco Pautasso

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  1. Marco Pautasso
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Correspondence to Marco Pautasso.

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Pautasso, M. Network simulations to study seed exchange for agrobiodiversity conservation. Agron. Sustain. Dev. 35, 145–150 (2015). https://doi.org/10.1007/s13593-014-0222-9

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