2,520 research outputs found
Climateâdriven evolutionary change in reproductive and earlyâacting lifeâhistory traits in the perennial grass Festuca ovina
Reproductive and earlyâacting lifeâhistory traits are likely to be particularly important determinants of plant fitness under a changing climate. There have, however, been few robust tests of the evolution of these traits under chronic climate change in natural ecosystems. Such studies are urgently needed, to evaluate the contribution of evolutionary change to population persistence.
Here, we examine climateâdriven evolutionary change in reproductive and earlyâacting plant lifeâhistory traits in the longâlived perennial plant, Festuca ovina.
We collected established plants of F. ovina from speciesârich calcareous grassland at the Buxton Climate Change Impacts Laboratory (BCCIL), after 17 years of in situ experimental drought treatment.
P1 plants collected from droughtâtreated and control (ambient climate) plots at BCCIL were used to create an openâpollinated F1 progeny array, which was subsequently validated using microsatellite markers to establish a robust biâparental pedigree. We measured the timing of germination and seed mass in the F1 progeny, the P1 paternal contribution to F1 offspring (paternal reproductive success), and assessed the effects of flowering time on the mating system.
F1 seed with ancestry in droughtâtreated plots at BCCIL germinated significantly later than seed derived from individuals from control plots. P1 plants from the drought treatment flowered significantly earlier than those from the control plots in summer 2012, but not in 2013. Male reproductive success was also lower in P1 plants collected from drought plots than those from control plots. Furthermore, our pedigree revealed that mating among parents of the F1 progeny had been assortative with respect to flowering time.
Synthesis. Our study shows that chronic drought treatment at Buxton Climate Change Impacts Laboratory has driven rapid evolutionary change in reproductive and earlyâacting lifeâhistory traits in Festuca ovina, and suggests that evolutionary differentiation may be reinforced through changes in flowering time that reduce the potential for gene flow
Links between soil microbial communities and plant traits in a species-rich grassland under long-term climate change
Climate change can influence soil microorganisms directly by altering their growth and activity but also indirectly via effects on the vegetation, which modifies the availability of resources. Direct impacts of climate change on soil microorganisms can occur rapidly, whereas indirect effects mediated by shifts in plant community composition are not immediately apparent and likely to increase over time. We used molecular fingerprinting of bacterial and fungal communities in the soil to investigate the effects of 17 years of temperature and rainfall manipulations in a speciesârich grassland near Buxton, UK. We compared shifts in microbial community structure to changes in plant species composition and key plant traits across 78 microsites within plots subjected to winter heating, rainfall supplementation, or summer drought. We observed marked shifts in soil fungal and bacterial community structure in response to chronic summer drought. Importantly, although dominant microbial taxa were largely unaffected by drought, there were substantial changes in the abundances of subordinate fungal and bacterial taxa. In contrast to shortâterm studies that report high resistance of soil fungi to drought, we observed substantial losses of fungal taxa in the summer drought treatments. There was moderate concordance between soil microbial communities and plant species composition within microsites. Vector fitting of communityâweighted mean plant traits to ordinations of soil bacterial and fungal communities showed that shifts in soil microbial community structure were related to plant traits representing the quality of resources available to soil microorganisms: the construction cost of leaf material, foliar carbonâtoânitrogen ratios, and leaf dry matter content. Thus, our study provides evidence that climate change could affect soil microbial communities indirectly via changes in plant inputs and highlights the importance of considering longâterm climate change effects, especially in nutrientâpoor systems with slowâgrowing vegetation
The Situation Analysis Approach to Assessing Family Planning and Reproductive Health Services: A Handbook
Good family planning service delivery emphasizing both access and quality is key to the related goals of satisfying individual needs and achieving programmatic success. Situation Analysis (SA) provides a needed link between the manager and the client he or she is trying to serve. The data marshaled for SA offer a representative picture of how subsystems are working and provide a way to âseeâ the clientâs experience. Situation Analyses assist managers in achieving the broadest management goalâthat of efficient administration of a vital health care service while keeping in view the ultimate goalâproviding good care for those who seek it. âThe Situation Analysis Approach to Assessing Family Planning and Reproductive Health Servicesâ handbook is a tool to help implement SA studies. Some of the sections are more valuable for policymakers and program planners, others for researchers, and still others for field interviewers. The handbook consists of four chapters: The Situation Analysis Study Methodology; Conducting the Study; Instruments and Question-by-Question Guides; and Data Analysis and Reporting
Structural features discriminate androgen receptor N/C terminal and coactivator interactions
Human androgen receptor (AR) transcriptional activity involves interdomain and coactivator interactions with the agonist-bound AR ligand binding domain (LBD). Structural determinants of the AR NH2- and carboxyl-terminal interaction between the AR NH2-terminal FXXLF motif and activation function 2 (AF2) in the LBD were shown previously by crystallography. In this report, we provide evidence for a region in AR LBD helix 12 outside the AF2 binding cleft that facilitates interactions with the FXXLF and LXXLL motifs. Mutagenesis of glutamine 902 to alanine in AR LBD helix 12 (Q902A) disrupted AR FXXLF motif binding to AF2, but enhanced coactivator LXXLL motif binding. Functional compensation for defective FXXLF motif binding by AR-Q902A was suggested by the slower dissociation rate of bound androgen. Functional importance of glutamine 902 was indicated by the charged residue germline mutation Q902R that caused partial androgen insensitivity, and a similar somatic mutation Q902K reported in prostate cancer, both of which increased the androgen dissociation rate and decreased AR transcriptional activity. High affinity equilibrium androgen binding was retained by alanine substitution mutations at Tyr-739 in AR LBD helix 5 or Lys-905 in helix 12 structurally adjacent to AF2, whereas transcriptional activity decreased and the androgen dissociation increased. Deleterious effects of these loss of function mutations were rescued by the helix stabilizing AR prostate cancer somatic mutation H874Y. Sequence NH2-terminal to the AR FXXLF motif contributed to the AR NH2- and carboxyl-terminal interaction based on greater AR-2-30 FXXLF motif peptide binding to the agonist-bound AR LBD than a shorter AR-20-30 FXXLF motif peptide. We conclude that helix 12 residues outside the AF2 binding cleft modulate AR transcriptional activity by providing flexibility to accommodate FXXLF or LXXLL motif binding
Managing learning trajectories: the case of 14-19 mathematics
In this paper we explore how mathematics department leaders manage curriculum (what is taught), teaching (how it is taught) and learner progression (what results) for 14-19 year olds. The background to the study is a range of national, and international, concerns about participation rates in university entrance level mathematics. Given the recommendation of the Smith Report (2004) that new pathways models be developed for 14-19 mathematics, this paper explores some of the strategies employed, and issues faced, by schools as they seek to maximise attainment and participation in mathematics. Following a thematic analysis of data from interviews with heads of department in fifteen schools we look in more depth at one school to see how it manages the mathematics learning trajectories of young people. The theme of performativity is all pervasive
Adaptation to chronic drought modifies soil microbial community responses to phytohormones
Drought imposes stress on plants and associated soil microbes, inducing coordinated adaptive responses, which can involve plantâsoil signalling via phytohormones. However, we know little about how microbial communities respond to phytohormones, or how these responses are shaped by chronic (long-term) drought. Here, we added three phytohormones (abscisic acid, 1-aminocyclopropane-1-carboxylic acid, and jasmonic acid) to soils from long-term (25-year), field-based climate treatments to test the hypothesis that chronic drought alters soil microbial community responses to plant stress signalling. Phytohormone addition increased soil respiration, but this effect was stronger in irrigated than in droughted soils and increased soil respiration at low phytohormone concentrations could not be explained by their use as substrate. Thus, we show that drought adaptation within soil microbial communities modifies their responses to phytohormone inputs. Furthermore, distinct phytohormone-induced shifts in microbial functional groups in droughted vs. irrigated soils might suggest that drought-adapted soil microorganisms perceive phytohormones as stress-signals, allowing them to anticipate impending drought
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