Abstract
Crop wild relatives (CWR) are important sources of adaptive diversity for plant breeding programmes. This paper aims to investigate the extent to which the centres of crop origin/diversity are congruent with areas of high CWR diversity. We established the predicted potential CWR distributions for 1,425 CWR species related to 167 crops using 334,527 known distribution locations and generated a global CWR hotspot map. This was then compared to the centres of origin/diversity proposed by Vavilov (amended by Hawkes); Zeven and Zhukovsky’s mega gene centres, Harlan’s centres and non-centres of crop domestication; and crop domestication areas identified using current archaeological evidence proposed by Purugganan and Fuller. Greatest congruence between the global CWR hotspots and other concepts was found with the concept proposed by Vavilov and amended by Hawkes, but there remained significant differences between the CWR hotspots and Vavilov’s concept. This paper concludes that all four centre concepts reviewed have some overlap with CWR diversity but that Vavilov’s original concept has the closest geographic coincidence with CWR hotspots. With the benefit of significant additional global datasets to those used by Vavilov, we were able to suggest amendments to his concept, adding further centres based on CWR hotspots in west and east USA, West Africa, South-east Brazil and Australia. As a result of this study more precise targeting of CWR and crop landrace can be implemented in future, aiding global food and nutritional security.
Highlights
Inspired by the work of de Candolle and Darwin, Vavilov attempted to define global crop domestication areas more precisely and published his theory on the centres of crop origins/diversity based upon a study of crop and wild relative literature, geography and nomenclature (Vavilov 1926)
In this paper we aim to investigate the extent to which the four centres of crop origin/diversity concepts are congruent with recently proposed high Crop wild relatives (CWR) diversity hotspots
Throughout the CWR conservation literature, it is often remarked that Vavilov centres origin/diversity are coincident with areas of high CWR diversity (Rubenstein et al 2005; Maxted and Kell 2009; Stolten et al 2010; Ford-Lloyd et al 2011; Hummer and Hancock 2015; Kell et al 2015)
Summary
The transition from hunter-gatherer communities to agriculture first occurred some 10,000 years ago in several independent localities globally (Diamond 2002). Vavilov initially identified five centres of plant crop origination using a so called differential phytogeographical approach which involved the following steps: (a) delimitation of plants into Linnean species and morphological units; (b) determination of the geographical distribution of these plants in the past; (c) determination of the inherited variation of characteristics of each plant species; (d) identification of geographical areas where there is a wide range of inherited variation in crop varieties and multiple wild relative species presence (Vavilov 1992) The five centres he initially identified were geographically broad and encompassed the Mediterranean, Central and South America, the Far East and South-western Asia. The identification of these centres of crop origins/diversity formed the foundation and rationale for many of Vavilov’s collecting missions
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