Germination behaviour of annual plants under changing climatic conditions: separating local and regional environmental effects |
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Authors: | Martina Petrů Katja Tielbörger |
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Institution: | (1) Department of Plant Ecology, University of Tübingen, Auf der Morgenstelle 3, 72076 Tübingen, Germany |
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Abstract: | The role of local adaptation and factors other than climate in determining extinction probabilities of species under climate
change has not been yet explicitly studied. Here we performed a field experiment with annual plants growing along a steep
climatic gradient in Israel to isolate climatic effects for local trait expression. The focus trait was seed dormancy, for
which many theoretical predictions exist regarding climate-driven optimal germination behaviour. We evaluated how germination
is consistent with theory, indicating local adaptation to current and changing climatic conditions, and how it varies among
species and between natural and standardised soil conditions. We reciprocally sowed seeds from three or four origins for each
of three annual species, Biscutella didyma, Bromus fasciculatus and Hymenocarpos circinnatus, in their home and neighbouring sowing locations along an aridity gradient. Our predictions were: lower germination fraction
for seeds from more arid origins, and higher germination at wetter sowing locations for all seed origins. By sowing seeds
in both local and standard soil, we separated climatic effects from local conditions. At the arid sowing location, two species
supported the prediction of low germination of drier seed origins, but differences between seed origins at the other sites
were not substantial. There were no clear rainfall effects on germination. Germination fractions were consistently lower on
local soil than on standard soil, indicating the important role of soil type and neighbour conditions for trait expression.
Local environmental conditions may override effects of climate and so should be carefully addressed in future studies testing
for the potential of species to adapt or plastically respond to climate change. |
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Keywords: | Bet-hedging Bioclimatic envelope approach Mediterranean climate Reciprocal sowing experiment Unpredictable environments |
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