Search

The Paleocene-Eocene Thermal Maximum (PETM; 56 Ma) is one of our best geological analogs for understanding climate dynamics in a "greenhouse" world. However, proxy data representing the event are only available from select marine and terrestrial sedimentary sequences that are unevenly distributed across Earth's surface, limiting our view of the spatial patterns of climate change. Here, we use paleoclimate data assimilation (DA) to combine climate model and proxy information and create a spatially complete reconstruction of the PETM and the climate state that precedes it ("PETM-DA"). Our data-constrained results support strong polar amplification, which in the absence of an extensive cryosphere, is related to temperature feedbacks and loss of seasonal snow on land. The response of the hydrological cycle to PETM warming consists of a narrowing of the Intertropical Convergence Zone, off-equatorial drying, and an intensification of seasonal monsoons and winter storm tracks. Many of these features are also seen in simulations of future climate change under increasing anthropogenic emissions. Since the PETM-DA yields a spatially complete estimate of surface air temperature, it yields a rigorous estimate of global mean temperature change (5.6 ∘C; 5.4 ∘C to 5.9 ∘C, 95% CI) that can be used to calculate equilibrium climate sensitivity (ECS). We find that PETM ECS was 6.5 ∘C (5.7 ∘C to 7.4 ∘C, 95% CI), which is much higher than the present-day range. This supports the view that climate sensitivity increases substantially when greenhouse gas concentrations are high.

Knowledge of the onset duration of the Paleocene-Eocene Thermal Maximum-the largest known greenhouse-gas-driven global warming event of the Cenozoic-is central to drawing inferences for future climate change. Single-foraminifera measurements of the associated carbon isotope excursion from Maud Rise (South Atlantic Ocean) are controversial, as they seem to indicate geologically instantaneous carbon release and anomalously long ocean mixing. Here, we fundamentally reinterpret this record and extract the likely PETM onset duration. First, we employ an Earth system model to illustrate how the response of ocean circulation to warming does not support the interpretation of instantaneous carbon release. Instead, we use a novel sediment-mixing model to show how changes in the relative population sizes of calcareous plankton, combined with sediment mixing, can explain the observations. Furthermore, for any plausible PETM onset duration and sampling methodology, we place a probability on not sampling an intermediate, syn-excursion isotopic value. Assuming mixed-layer carbonate production continued at Maud Rise, we deduce the PETM onset was likely

Abstract Background Hybrid zones represent valuable opportunities to observe evolution in systems that are unusually dynamic and where the potential for the origin of novelty and rapid adaptation co-occur with the potential for dysfunction. Recently initiated hybrid zones are particularly exciting evolutionary experiments because ongoing natural selection on novel genetic combinations can be studied in ecological time. Moreover, when hybrid zones involve native and introduced species, complex genetic patterns present important challenges for conservation policy. To assess variation of admixture dynamics, we scored a large panel of markers in five wild hybrid populations formed when Barred Tiger Salamanders were introduced into the range of California Tiger Salamanders. Results At three of 64 markers, introduced alleles have largely displaced native alleles within the hybrid populations. Another marker (GNAT1) showed consistent heterozygote deficits in the wild, and this marker was associated with embryonic mortality in laboratory F2's. Other deviations from equilibrium expectations were idiosyncratic among breeding ponds, consistent with highly stochastic demographic effects. Conclusion While most markers retain native and introduced alleles in expected proportions, strong selection appears to be eliminating native alleles at a smaller set of loci. Such rapid fixation of alleles is detectable only in recently formed hybrid zones, though it might be representative of dynamics that frequently occur in nature. These results underscore the variable and mosaic nature of hybrid genomes and illustrate the potency of recombination and selection in promoting variable, and often unpredictable genetic outcomes. Introgression of a few, strongly selected introduced alleles should not necessarily affect the conservation status of California Tiger Salamanders, but suggests that genetically pure populations of this endangered species will be difficult to maintain.

BackgroundEstablishing genomic resources for closely related species will provide comparative insights that are crucial for understanding diversity and variability at multiple levels of biological organization. We developed ESTs for Mexican axolotl (Ambystoma mexicanum) and Eastern tiger salamander (A. tigrinum tigrinum), species with deep and diverse research histories.ResultsApproximately 40,000 quality cDNA sequences were isolated for these species from various tissues, including regenerating limb and tail. These sequences and an existing set of 16,030 cDNA sequences for A. mexicanum were processed to yield 35,413 and 20,599 high quality ESTs for A. mexicanum and A. t. tigrinum, respectively. Because the A. t. tigrinum ESTs were obtained primarily from a normalized library, an approximately equal number of contigs were obtained for each species, with 21,091 unique contigs identified overall. The 10,592 contigs that showed significant similarity to sequences from the human RefSeq database reflected a diverse array of molecular functions and biological processes, with many corresponding to genes expressed during spinal cord injury in rat and fin regeneration in zebrafish. To demonstrate the utility of these EST resources, we searched databases to identify probes for regeneration research, characterized intra- and interspecific nucleotide polymorphism, saturated a human – Ambystoma synteny group with marker loci, and extended PCR primer sets designed for A. mexicanum / A. t. tigrinum orthologues to a related tiger salamander species.ConclusionsOur study highlights the value of developing resources in traditional model systems where the likelihood of information transfer to multiple, closely related taxa is high, thus simultaneously enabling both laboratory and natural history research.

This article deals with the education of older adults in communities with different levels of well-being. We are interested in whether the educational offerings for older adults depend on the well-being of the local community. We also examine how the educational offerings differ depending on whether the community is primarily rural or urban. In the research, the case study design was used. Municipalities were selected with respect to their level of well-being and compared regarding the educational offering for older adults. The analysis of the selected municipalities shows that the offering of educational opportunities for the older adults is more connected to the degree of urban and/or the rural character of the community than to the well-being of the community. One of the main obstacles for access to education of older adults appears to be geographical distance. In this research, we establish that the providers of education for older adults and the community's organizational cohesiveness in Slovenia do not cooperate with each other as a rule. There is also no in-depth consideration by education organizers for how to attract the older adults who don't take part in educational activities.

This article takes a psychological perspective on organisational learning, putting "reflection" into the centre of attention. We argue that (1) organisational learning is based on individual and team learning at work, (2) reflection is the driving force that leads to organisational learning and (3) cumulation of the staff's reflection outcomes allows for integration of individual and team learning into organisational best practice. Building on a vast amount of theory in this area, we provide a refined psychological model of the socio-cognitive processes of reflective learning within organisations including the initiation and the termination of reflection. Further, we discuss in depth the role of reflection for organisational learning in the light of recent theories of organisational learning. (Contains 4 figures.)

Educating older adults (in the so-called third age) is becoming an increasingly important activity for the elderly, above all because it empowers them, while at the same time reducing their social exclusion. The aim of this paper is to closely examine the actual state of affairs and the education possibilities for older adults in Slovenia. The article deals with a secondary analysis of data that was collected in three Slovene researches dealing with the participation of adults in the education process in 1987, 1998 and 2004. The purpose of the analysis is to examine the changes in the participation of the older adults, their motivation for education and barriers that have dissuaded them from education. Special attention is devoted to the development of the offer of educational programmes for older adults in Slovenia. The authors state that the offer of education for older adults has improved between 1987 and 2004, while the participation has declined. The older adults mentioned a number of various barriers that represent the reasons for the decline in their participation, however the major obstacle is the low educational level of older adults. (Contains 1 table and 8 notes.)

Describes the Slovenian system of higher education and the country's new effort to establish an improved system. A draft plan for introducing a system of quality assurance into the relatively small existing system has been developed based on foreign experience, with attention to Slovenian national needs. Evaluation will be an integral part of the new system. (SLD)