Evolution of wild cereals during 28 years of global warming in Israel

Abstract

Climate change is a major environmental stress threatening biodiversity and human civilization. The best hope to secure staple food for humans and animal feed by future crop improvement depends on wild progenitors. We examined 10 wild emmer wheat (Triticum dicoccoides Koern.) populations and 10 wild barley (Hordeum spontaneum K. Koch) populations in Israel, sampling them in 1980 and again in 2008, and performed phenotypic and genotypic analyses on the collected samples. We witnessed the profound adaptive changes of these wild cereals in Israel over the last 28 y in flowering time and simple sequence repeat allelic turnover. The revealed evolutionary changes imply unrealized risks present in genetic resources for crop improvement and human food production.climate warming | phenotypic and genotypic diversity | plant genetic resources I n recent decades there have been increasing concerns about the future of food production influenced by climate change (1-7) to feed a fast growing world population reaching 9-10 billion by 2050 (8). Aridization has alarmingly increased in summer, resulting in dry regions of wheat growing areas, particularly in the Americas, Asia, and Africa, and in the area of origin and diversity of wild emmer wheat in the Near East (9). Cultivated wheat, the number one world food staple, is genetically impoverished by long-term selective breeding (10). The wild progenitors of cultivated cereals, especially wild emmer wheat Triticum dicoccoides Koern. (TD) (9) and wild barley Hordeum spontaneum K. Koch (HS) (11), have become eroded by urbanization and agriculture (12). Both progenitors are rich in genetic resources adapted to abiotic (e.g., solar radiation, temperature, drought, and mineral poverty) and biotic (e.g., pathogens and parasites) stresses. These progenitors are the best genetic hope for improving genetically impoverished cultivars for human food production (9-17). Thus, it is crucial to evaluate the evolutionary adaptation in natural populations of the progenitors under climate change and to understand the hidden risk in human food security. Here we examined 10 TD populations and 10 HS populations in Israel from 1980 and again in 2008 and performed phenotypic and genotypic analyses on the collected samples. We witnessed the profound adaptive changes of these wild cereals in Israel over the last 28 y in flowering time (FT) and simple sequence repeat (SSR) allelic turnover. ResultsPhenotypic Analysis. In a greenhouse experiment, we compared the time from germination until flowering of ∼800 genotypes in 20 natural populations from different habitats and climates that were subjected to 28 y of climate change. The sampled populations (16, 17) were distributed across 350 km of their Israeli range (SI Appendix, Fig. S1 and Table S1). A total of 57 independent pair-wise comparisons were made under dry (300 mm) and wet (600 mm) irrigation regimes. Dramatically, in all TD and HS populations, without exception, the 2008 populations reached FT earlier than those collected in 1980 (Sign test, P < 1...

DNA sequence variation of wild barley Hordeum spontaneum (L.) across environmental gradients in Israel

“…Although the observed patterns are similar to previous studies, and consistent with local adaptation, the analysis of neutral demographic models suggested a strong demographic contribution to the observed structure, which does not support a simple selectionist explanation, particularly in EC1. Differences from previous studies indicate an effect of marker types, collections and temporal changes in the population (Nevo et al, 2012). Future studies of wild barley adaptation should be carried out with additional samples around microsites such as the EC and be combined them with large systematic collections like the Barley1K (Hubner et al, 2009) to put the local patterns of genetic variation into a broader geographic context.…”

Evolutionary and Ecological Responses to Anthropogenic Climate Change

“…By comparing phenotypes, fitness components, and allelic richness in lineages derived from seeds collected before and after environmental change, Franks et al (2007) detected rapid evolution in response to drought and Nevo et al (2012) uncovered evolution in response to gradually changing climates. Indeed, a recent largescale effort to store seeds has the explicit goal of providing lineages for future studies of the evolutionary response to temporal variation, especially in the context of climate change (for review, see Shaw and Etterson, 2012).…”

“…Resurrection studies can estimate the rate of trait evolution; investigate the fitness consequences of climate change; dissect the genetic basis of rapid adaptation to disturbance with mapping populations and genomic approaches; distinguish between plasticity and adaptation; and test hypotheses about how specific environmental perturbations select on complex traits and plasticity (hypotheses 1, 2, 3, and 5; see Franks et al, 2007;Nevo et al, 2012;Shaw and Etterson, 2012). These investigations could also determine whether populations can evolve to rely on new triggers for life history transitions as temperature, photoperiod and other environmental cues become decoupled from each other.…”

A physical, genetic and functional sequence assembly of the barley genome

“…Approximately three-quarters of global production is used for animal feed, 20% is malted for use in alcoholic and non-alcoholic beverages, and 5% as an ingredient in a range of food products 2 . Barley is widely adapted to diverse environmental conditions and is more stress tolerant than its close relative wheat 3 . As a result, barley remains a major food source in poorer countries 4 , maintaining harvestable yields in harsh and marginal environments.…”