Genetic Resources and Crop Evolution

, Volume 64, Issue 4, pp 665–680 | Cite as

Perceptual selection and the unconscious selection of ‘volunteer’ seedlings in clonally propagated crops: an example with African cassava (Manihot esculenta Crantz) using ethnobotany and population genetics

Research Article


The role of sexual reproduction in magnifying genetic diversity in clonally propagated crops is now well documented. But whereas many studies have emphasized the importance of perceptual distinctiveness and its role in arousing farmers’ curiosity towards plants with unusual morphological traits, few have considered its corollary, perceptual indistinctiveness. In this study, we investigated which factors influence farmers’ behaviours towards self-sown ‘volunteer’ seedlings of cassava (Manihot esculenta Crantz) in a cross-cultural survey in Gabon, Central Africa. Interviews revealed that farmers were seven times more likely to spare seedlings that resembled a named landrace compared to those that did not. Similarly, farmers were more likely to relax weeding pressures on cassava volunteers if they believed that volunteers were resurgences from old cuttings. The model fit significantly improved when cultural factors were accounted for, suggesting strong culture-dependent differences among communities in their perception of and attitudes towards cassava volunteers. An analysis of the structure of genetic diversity of cassava landrace populations at the community level showed that most landraces included singleton genotypes, even in villages where farmers imposed the strongest weeding pressures, suggesting that there is always some background incorporation of cassava seedlings. We show that by channelling the selective incorporation of cassava seedlings that are morphologically indistinguishable from familiar landraces, perceptual selection favors the recruitment, sometimes deliberate but more often unconscious, of new genotypes from plants germinating from seeds and contributes to balancing the disadvantages of strictly clonal propagation, while maintaining landraces within consensual combinations of perceptually distinct traits.


Cassava (Manihot esculenta Crantz) Conditional inference tree Mixed clonal/sexual reproduction Perceptual selection Secondary center of diversity Unconscious incorporation 



This paper draws from the first author’s doctoral thesis at Trinity College, University of Dublin. Research was funded by a grant (RS/2005/44) to MD from The Irish Research Council for Science, Engineering and Technology (IRCSET, funded under the National Development Plan). Additional funding was received from IRCSET and Teagasc under the France-Ireland Hubert Curien Partnership ‘Ulysses’. The authors thank the Laboratoire Universitaire des Traditions Orales et Dynamiques Contemporaines (LUTO-DC) and the Université Omar Bongo (UOB) of Libreville, who hosted the project in Gabon (research authorizations 0030/MESRIT/UOB/R, 76/MISPD/PHO/CAB, 00108/MENES/UOB/R, 00130/MESR/UOB/VRAAC), and the farmers in Gabon.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Supplementary material

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Supplementary material 1 (DOCX 96 kb)
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Supplementary material 2 (DOCX 35 kb)
10722_2016_390_MOESM3_ESM.docx (32 kb)
Supplementary material 3 (DOCX 33 kb)


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Copyright information

© Springer Science+Business Media Dordrecht 2016

Authors and Affiliations

  1. 1.School of Natural Sciences, Botany BuildingTrinity College DublinDublin D2Ireland
  2. 2.Plant and AgriBiosciences Research Centre (PABC)National University of Ireland Galway (NUNG)GalwayIreland
  3. 3.Centre d’Ecologie Fonctionnelle et Evolutive, CEFE UMR 5175CNRS – Université de Montpellier – Université Paul Valéry Montpellier – EPHEMontpellier Cedex 5France
  4. 4.Institut Universitaire de FranceParisFrance

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