Timing of flowering is an adaptive trait regulated by environmental cues and has been intensively studied in annual plants, but in perennials it is currently not well characterized. Quilot-Turion et al. apply cold treatments to two locally adapted populations of the perennial Arabidopsis lyrata from central Europe and Scandinavia and study responses to vernalization. They find that the population from central Europe flowers more rapidly and invests more in inflorescence growth than the Scandinavian population, which has longer leaves and higher leaf rosettes. QTL mapping in the F2 population reveals genomic regions governing these traits and some QTL × vernalization interactions. The results indicate that the two populations have diverged in their plastic responses to vernalization in traits closely connected to fitness through changes in many genomic areas.
Early life-history stages of cacti can benefit from the facilitative effects of nurse plants that reduce solar radiation and water stress. Miranda-Jácome et al. conduct a reciprocal transplant experiment, coupled with the artificial manipulation of sun/shade conditions, to test for the effects of local adaptation on germination, seedling survival and growth of the columnar cactus Pilosocereus leucocephalus. They find that significant local adaptation is mainly detected under full sunlight conditions, indicating that sun/shade acts as a selective agent in water-limited environments. Facilitation provided by nurse plants in these environments can attenuate the patterns of local adaptation among plants benefiting from nurse plant effects.
Responses of high-mountain plant species to global change are highly influenced by the genetic background of the species, including genetic diversity or gene flow between populations. García-Fernández et al. study the genetic patterns of Silene ciliata (Caryophyllaceae), a high-mountain cushion plant that shows local adaptation to altitude, by examining populations along two altitudinal gradients on separate mountains in central Spain. They find that genetic diversity is similar in all populations, and although substantial gene flow is found both along altitudinal gradients and horizontally within each elevation belt, greater values are obtained along altitudinal gradients.
Early life history stages are among the most critical phases in the life cycle of plants. De Frenne et al. assess the response of plant regeneration from seed of two forest understorey plants (Anemone nemorosa and Milium effusum) to variations in temperature along a latitudinal gradient. They find decreasing seedling emergence and fitness towards the northern edge of the distribution range of the species, as well as stronger growth responses to temperature increases in northern than in southern seedlings of the grass M. effusum. They conclude that wide intraspecific variation in plant regeneration in response to warming may differentially alter future plant dynamics across broad spatial scales.
Population differentiation in a variable environment is related to the selection pressures that plants experience. Ward et al. compare differences in growth- and defence-related traits in two isolated populations of Acacia raddiana trees from sites at either end of an extreme environmental gradient in the Negev desert. They find no evidence of trade-offs between physical and chemical defences and plant growth parameters; rather, there appears to be positive correlations between plant size and defence parameters. The great variation in several traits in both populations may result in a diverse potential for responding to selection pressures in different environments.
Mertensia fusiformis (Boraginaceae) is a spring-flowering perennial showing pronounced intraspecific variation in style length and stigma–anther separation. Forrest et al. show that population-level variation in flowering time, driven by patchiness in timing of snowmelt, causes different populations to experience different temperature regimes during flowering and functionally distinct suites of pollinators. The interaction between plant and pollinator phenology in particular appears to be involved in maintaining style-length variation in this species.