Nutrients, arbuscular mycorrhizas and competition interact to influence seed production and germination success in Achillea millefolium

1. Environmental variables that positively affect one aspect of plant fitness, may have no effect, or even negatively affect some other component of fitness. 2. Using individuals of Achillea millefolium grown under field conditions in Michigan, USA, the hypothesis was tested that seed number was determined largely by plant biomass, while seed germination success depends on tissue nutrient concentrations. The impact was assessed of four biotic and abiotic factors on seed number and germination success: root competition, shoot competition, fertilizer, and removal of fungi by fungicide application. 3. Using a path analysis, it was found that total plant biomass positively affected both seed number and germination success, while inclusion of other variables did not greatly affect the amount of variation the model was able to explain. Fertilizer and fungicide increased, while root and shoot competition decreased both seed number and germination. 4. Fungicide applied to the maternal plant increased biomass but decreased tissue phosphorus concentrations. In species where germination responds to nutrient concentrations, the potential exists for opposing impacts of environmental treatments on different components of fitness. 5. This study suggests that environmental impacts on seed number will outweigh impacts on germination success under field conditions, and that biomass is an adequate surrogate for fitness in herbaceous plants.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71905/1/j.1365-2435.2002.00675.x.pd

Heritability of seed weight in Maritime pine, a relevant trait in the transmission of environmental maternal effects

Quantitative seed provisioning is an important life-history trait with strong effects on offspring phenotype and fitness. As for any other trait, heritability estimates are vital for understanding its evolutionary dynamics. However, being a trait in between two generations, estimating additive genetic variation of seed provisioning requires complex quantitative genetic approaches for distinguishing between true genetic and environmental maternal effects. Here, using Maritime pine as a long-lived plant model, we quantified additive genetic variation of cone and seed weight (SW) mean and SW within-individual variation. We used a powerful approach combining both half-sib analysis and parent-offspring regression using several common garden tests established in contrasting environments to separate G, E and G x E effects. Both cone weight and SW mean showed significant genetic variation but were also influenced by the maternal environment. Most of the large variation in SW mean was attributable to additive genetic effects (h(2) = 0.55-0.74). SW showed no apparent G x E interaction, particularly when accounting for cone weight covariation, suggesting that the maternal genotypes actively control the SW mean irrespective of the amount of resources allocated to cones. Within-individual variation in SW was low (12%) relative to between-individual variation (88%), and showed no genetic variation but was largely affected by the maternal environment, with greater variation in the less favourable sites for pine growth. In summary, results were very consistent between the parental and the offspring common garden tests, and clearly indicated heritable genetic variation for SW mean but not for within-individual variation in SW.This study was financed by the Spanish National Research Grants RTA2007-100 and AGL2012-40151 (FENOPIN), both co-financed by EU-FEDER. The progeny trials and the clonal seed orchards are part of the experimental set up of the Maritime pine breeding programme developed by the Centro de Investigacion Forestal de Lourizan, Xunta de Galicia.Spanish National Research Grant RTA2007-100Spanish National Research Grant AGL2012-40151 (FENOPIN)EU-FEDERPeer reviewe

The actualization of the critical impulse in critical theory : dialogical rationality around Rachel`s tomb in Bethlehem, Palesine

In this review article, Isaac and Platenkamp argue that during the 1930s and 1940s of the previous century, concepts like "critical" and "essence" were still defined and understood in the tradition of what increasing numbers of academics called "Critical Theory." However, they suggest that since then the situation has significantly changed. In their view, while Critical Theory critically approaches the ideologies of the modern Western world, it has actually (itself) became a victim of this overwhelming critique of ideologies. To Isaac and Platenkamp, the main conceptualizations in and for Critical Theory have been weakened by a content inflation in the new historical phase of postmodernism. Thus, for instance, as a concept "criticism" had been revitalized to (down to?) a relativist position. In this review article, Isaac and Platenkamp suggest that academics in Tourism Studies now inherently claim to be "critical" by just appropriating the mere qualification critical, ipso facto. In this light, the old vital value of "Essence" thereby has become a superficial concept of old primitive ideologies, today, and it seems to have no meaningful function anymore in Tourism Studies. This review article thus aims to reintroduce the field of Tourism Studies to Marcuse's original concept of Essence and discuss it vis-à-vis its interpretational confrontation with the said postmodernist position and thereby to the very revitalization of the qualification "critical." Hence, Isaac and Platenkamp seek to save this qualification from the postmodernist attacks on the universality of the Critical Theoretical position by drawing particular attention to Arendt's concept of the agora, viz. as that kind of public space (comparable to the forum Romanum), in which people significantly present themselves as individuals with independent opinions. In this regard, Isaac and Platekamp are particularly disturbed by the recent flowering of the so called "Critical Turn" group (or network) within Tourism Studies since it appears to progress without a thorough understanding of Critical Theory, per se. They argue that classical thinkers of Critical Theory need to be addressed and understood if the Critical Turn group of scholars in Tourism Studies may decently/faithfully/meaningfully be deemed to be critical. In order to make their case, Isaac and Platenkamp highlight the case of Rachel's Tomb in Bethlehem. They position the Tomb as a very important biblical tourism site (and agora) by and through which the revitalization of the "critical" may be incorruptibly recognized