Measuring and predicting change in crop wild relative species

1. Measuring and predicting change in crop wild relative species by Toby Hodgkin and Jozef Turok International Plant Genetic Resources Institute (IPGRI), Rome, Italy

2. What is a crop wild relative? • Self- and out-pollinating annuals • Grassland species • Temperate forest trees (angiosperms, gymnosperms) • Weedy species • Rare, mountain endemic plants

3. Large variation in the characteristics… • Distribution extent and pattern • Longevity • Life form • Habitat • Are crop wild relative species different with respect to change, erosion and pollution?

4. Pollution • Substantial gene flow from cultivated species to primary genepool species, which are fully inter-fertile, occur together and overlap in flowering period • Examples: Hordeum spontaneum, Oryza rupifogon, Teosinte, Pennisetum, Beta maritima

5. Conservation objectives • Conservation of the full amplitude of variation within a species • Conservation of specific traits (frost or drought resistance)

6. Change • Erosion and genetic pollution • Global changes of the environment • Effects of the global climate change on crop wild relative species • Factors and processes of evolutionary change • Methods to assess change

7. Dispersal capability • Depends on seed biology and vector of dispersal • For long-term survival of a species under global climate change, the dispersal capability must be greater than the speed of environmental change

8. Gene flow Pheno-typic plasti-city Natural selection Genetic drift Mu-ta-tions Inter-population differentiation Constraints Promoters Eriksson (2003)

9. Factors and processes of evolutionary change • Natural selection • Genetic drift • Mutation • Gene flow • Mating system and recombination • Phenotypic plasticity

10. Change of survival, % 20 1 0 Norm of reaction 0 Phenotypic plasticity –10 –20 –30 +3 +2 +1 0 –1 –2 –3 –4 –5 northwards southwards Latitudinal transfer Phenotypic plasticity Eriksson (2003)

11. Indicators of change Indicator taxa: • Utility value or known ecological significance • Existence value, for species under threat of extinction • Value for species known to be paradigms of a large class of species Indicators of genetic variation: • Easy to implement, based on good experimental design, indicate processes and flows, give early warnings, have clear objectives • Application of population genetics – conservation of the processes that maintain current genetic variation Namkoong et al. (2002); McKenney et al. (1994)

12. Indicators of change 1. Number of sub-specific taxa 2. Population size and physical location 3. Environmental amplitude of populations 4. Genetic diversity at marker loci within individuals and populations 5. Quantitative genetic variation 6. Inter-population genetic structure 7. Mating system Brown et al. (1997)

13. Indicators of change Criterion: Conservation of the processes that maintain genetic variation • Levels of genetic variation • Directional change in gene or genotype frequencies • Gene migration between populations • Reproductive processes/ mating system Namkoong et al. (2002)

14. Gene flow Raybould et al. (1996)

15. Genetic erosion “The loss of genetic diversity, in a particular location and over a particular period of time, including the loss of individual genes (alleles), and the loss of particular combinations of genes such as those manifested in landraces or varieties. It is thus a function of change of genetic diversity over time.” FAO (GDEV paper prepared for 9th Session of CGRFA, 2002)

16. Genetic erosion – measurement and monitoring

17. Genetic pollution • Exotic species (crops, forages and forest trees) • Artificial hybrids (Populus, Brassica napus) • Exotic provenances (crops, forages and forest trees) • Artificially selected plants (mainly forest trees and forages) • GMOs (mainly crops such as cotton, maize, Brassica, soybean relatives) Potts et al. (2001)

18. Pollution – why does it matter? • Loss or disruption of adaptive gene complexes • Introduction of “domestication genes” and therefore loss of natural survival capacities • Increase of susceptibility to pests • Loss of out-breeding characteristics (thus inbreeding depression) • Vigor loss in hybrids • Increase in weedy habit

19. Genetically modified organisms • Vigor and likelihood of out-crossing (e.g. through spread of crop to new areas) • The genes themselves – herbicide resistance, pest resistance • Disruption of pollinator and plant communities

20. Transgene escape • Plant containing it persists after harvesting in an agricultural or disturbed habitat or invades a natural habitat • Transgene is transferred by pollination to another crop which persists in an agricultural, disturbed or natural habitat • Transgene is transferred by pollination to a related wild plant which persists in agricultural habitats, disturbed habitats or natural habitats Raybould and Gray (1993)

21. Potential indicators • Existence of crop wild relatives in area (numbers and relationships) • Viability and fertility of progeny • Breeding system and extent of synchrony of flowering; presence of pollinators • Extent to which subsequent generations can remain fertile and backcross • Migration selection balance for transgene Gepts and Papa (2003)

22. Conclusions • Sufficient genetic variation within species • Criteria and indicators: baseline data to show trends • Important measurements, methods • Early warning • Trans-national monitoring and policy advice