Genetic Diversity and Ecological Niche Modelling of Wild Barley:Refugia, Large-Scale Post-LGM Range Expansion and Limited Mid-Future Climate Threats?

Describing genetic diversity in wild barley (Hordeum vulgare ssp. spontaneum) in geographic and environmental space in the context of current, past and potential future climates is important for conservation and for breeding the domesticated crop (Hordeum vulgare ssp. vulgare). Spatial genetic diversity in wild barley was revealed by both nuclear- (2,505 SNP, 24 nSSR) and chloroplast-derived (5 cpSSR) markers in 256 widely-sampled geo-referenced accessions. Results were compared with MaxEnt-modelled geographic distributions under current, past (Last Glacial Maximum, LGM) and mid-term future (anthropogenic scenario A2, the 2080s) climates. Comparisons suggest large-scale post-LGM range expansion in Central Asia and relatively small, but statistically significant, reductions in range-wide genetic diversity under future climate. Our analyses support the utility of ecological niche modelling for locating genetic diversity hotspots and determine priority geographic areas for wild barley conservation under anthropogenic climate change. Similar research on other cereal crop progenitors could play an important role in tailoring conservation and crop improvement strategies to support future human food security

Differentiation along a gradient of environmental productivity and predictability in populations of Hordeum spontaneum Koch: Multilevel selection analysis

A contextual analysis combined with path analysis was applied to detect ecotype-specific past selection in hierarchically structured populations of wild barley, Hordeum spontaneum. In our analysis a multiple regression model incorporated several individual and ecotype-level unmeasured (derived) traits obtained by factor analysis from 20 measured morphological and phenological traits. Under favourable conditions (high water and nutrients) both individual and ecotype plant size (RF1) were significant predictors of individual plant fitness, estimated by either reproductive biomass or yield. Both individual and ecotype size of reproductive structures (RF2) were significantly related to individual reproductive biomass. Individual yield, however, significantly correlated with ecotype RF2 only. Transition to reproduction (RF3) correlated with neither reproductive biomass nor yield at individual level, but correlated with two estimates of fitness at ecotype level. In all cases, selection at the individual and ecotype levels was in opposition. We interpret the observed effect of ecotype identity on individual fitness not as a current group selection, but as a constraining effect of ecotype-specific past selection. The four ecotypes went through an environmentally specific selection process in their own environments with the optimal strategy evolved. Consequently, this strategy may have a constraining effect on plant performance in other environments. Under conditions of either low water or low nutrients the ecotype level did not contribute to individual fitness. The latter may suggest that a mechanism for plant responses to stress is largely independent of plant origin, with a difference between ecotypes under stressful conditions due entirely to the difference in amount, not architecture, of plasticity. © 2002 The Linnean Society of London.Articl

Differentiation in populations of <I>Hordeum spontaneum </I>Koch along a gradient of environmental productivity and predictability: plasticity in response to water and nutrient stress.

AgriwetenskappeBewaringsekologiePlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected]

Differentiation along a gradient of environmental productivity and predictability in populations of <I>Hordeum spontaneum </I>Koch: Multilevel selection analysis.

AgriwetenskappeBewaringsekologiePlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected]

Differentiation in populations of Hordeum spontaneum along a gradient of environmental productivity and predictability: Life history and local adaptation

Reciprocal introduction of seeds and seedlings of wild barley, Hordeum spontaneum, originating in four different environments of Israel was used to: (1) test for local adaptation, (2) make inferences about environmental effects on life-history and reproductive traits, and (3) identify trait combinations with recognizable 'strategies'. The four populations examined represented the following environments: (1) desert - low productivity and predictability, drought stress; (2) semi-steppe batha - moderate productivity and predictability; (3) grassland - high productivity and predictability; and (4) mountain - high productivity and predictability but with severe frost stress. Significant genotype-by-environment interactions were observed for yield and reproductive biomass, seedling biomass and percentage germinated and survived seeds, suggesting local ecotype adaptation. Increasing productivity and predictability of environment in respect to rainfall, without concomitant frost stress, was found to select for high reproductive biomass and large seeds, a high fraction of germinating seeds and high vigour of seedlings. The optimal strategy changes with increasing productivity and predictability and involves a trade-off between seed size and number, with reduced yield but increased seed mass, consistent with competition selection (or K-selection sensu MacArthur & Wilson (1967)) type. No specific life-history adaptations to predictable frost stress were detected for the mountain ecotype, but there was higher survival of seedlings in their indigenous (mountain) environment compared with other ecotypes. The latter appears to be a physiological adaptation to frost, which is consistent with selection for stress tolerance (or S-selection sensu Grime (1977)) type. The other stress factor, drought, which is very unpredictable in deserts, was associated with high seed dormancy, small seed size and low vigour of seedlings, but relatively high yield, which is consistent with a stress-escape bet-hedging strategy. © 2002 The Linnean Society of London.Articl

Regional Subdivision in Wild Barley Allozyme Variation: Adaptive or Neutral

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Differentiation in populations of Hordeum spontaneum Koch along a gradient of environmental productivity and predictability: Plasticity in response to water and nutrient stress

Plants from four populations of Hordeum spontaneum originating in distinct environments of Israel were compared for stress induced phenotypic plasticity. The environments ranged along a gradient of increasing rainfall amount and predictability from low (desert) to moderate (semisteppe batha) to high (Mediterranean grassland and mountain, the latter also experiencing frost stress). The plants were exposed to a set of four treatments: no stress (optimum water and nutrients), water, nutrient and both water and nutrient stress. Plants from the four populations (or ecotypes) exhibited different patterns of plasticity in response to the different stresses (water and nutrients) and in different trait categories (reproductive, fitness and resource allocation). The importance of plasticity in response to water stress appears to decrease, and to nutrient stress appears to increase along the increasing rainfall gradient. The mountain ecotype, growing in an area with high potential productivity (amount of rainfall) but experiencing periodic frosts, was the most plastic among ecotypes in resource allocation under both water and nutrient stress, but exhibited low plasticity in other trait categories. In contrast, the desert ecotype had low plasticity in resource allocation under water stress and the lowest plasticity among the four ecotypes in all trait categories in response to nutrient stress. The ecotype originating in Mediterranean grassland, a predictable and most favourable environment, was highly plastic in fitness and allocation traits in response to low nutrient levels which is likely to occur due to competition in productive environment. We discuss the observed differences in ecotype plasticity as part of their environmentally induced adaptive 'strategies'. We found no support for the hypothesis that plants originating in environments with greater variation and unpredictability are more plastic. © 2002 The Linnean Society of London.Articl