Search results for "education.field_of_study"
showing 10 items of 7167 documents
A multi-proxy, diachronic and spatial perspective on the urban activities within an indigenous community in medieval Riga, Latvia
2017
Abstract The research presented here represents the first urban medieval context in Latvia where an integrated, multi-proxy environmental sampling strategy has been applied. The establishment of Riga, the modern capital of Latvia, is synonymous with the Livonian Crusade, and the foundation of the medieval town is examined here. This study uses an intra-site comparison of environmental datasets from several buildings to provide a unique, high resolution, diachronic analysis of the daily life of the inhabitants within the pre-Hansa town, and specifically of the indigenous ‘Liv’ population during the period of the Livonian crusades, 1198–1291. The integrated zooarchaeological, archaebotanical,…
The ecogenetic link between demography and evolution: can we bridge the gap between theory and data?
2007
Calls to understand the links between ecology and evolution have been common for decades. Population dynamics, i.e. the demographic changes in populations, arise from life history decisions of individuals and thus are a product of selection, and selection, on the contrary, can be modified by such dynamical properties of the population as density and stability. It follows that generating predictions and testing them correctly requires considering this ecogenetic feedback loop whenever traits have demographic consequences, mediated via density dependence (or frequency dependence). This is not an easy challenge, and arguably theory has advanced at a greater pace than empirical research. Howeve…
Consistent response of bird populations to climate change on two continents
2016
Global climate change is a major threat to biodiversity. Large-scale analyses have generally focused on the impacts of climate change on the geographic ranges of species, and on phenology, the timing of ecological phenomena. Here, we use long-term monitoring of the abundance of breeding birds across Europe and the USA to produce, for both regions, composite population indices for two groups of species: those for which climate suitability has been either improving or declining since 1980. The ratio of these composite indices, the Climate Impact Indicator (CII), reflects the divergent fates of species favored or disadvantaged by climate change. The trend in CII is positive and similar in the …
Using Local Ecological Knowledge of Fishers to Reconstruct Abundance Trends of Elasmobranch Populations in the Strait of Sicily
2020
Fishers “local ecological knowledge” (LEK) can be used to reconstruct long-term trends of species that are at very low biomass due to overfishing. In this study, we used historical memories of Sicilian fishers to understand their perception of change in abundance of cartilaginous fish in the Strait of Sicily over the last decades. We conducted interviews with 27 retired fishers from Mazara del Vallo harbor (SW Sicily) working in demersal fisheries, using a pre-defined questionnaire with a series of open and fixed questions related to the abundance of sharks and rays. The questionnaire included specific questions about the trends they perceived in catch or by-catch of cartilaginous fish abun…
Use of nursery areas by the extinct megatooth shark Otodus megalodon (Chondrichthyes: Lamniformes)
2020
Nursery areas are fundamental for the success of many marine species, particularly for large, slow-growing taxa with low fecundity and high age of maturity. Here, we examine the population size-class structure of the extinct gigantic shark Otodus megalodon in a newly described middle Miocene locality from Northeastern Spain, as well as in eight previously known formations (Temblor, Calvert, Pisco, Gatún, Chucunaque, Bahía Inglesa, Yorktown and Bone Valley). In all cases, body lengths of all individuals were inferred from dental parameters and the size-class structure was estimated from kernel probability density functions and Gaussian mixture models. Our analyses support the presence of fi…
Systematic revision of the Late Miocene sabre-toothed felid Paramachaerodus in Spain
2010
Abstract: A systematic revision of the sabre-toothed cat genus Paramachaerodus Pilgrim, 1913 is presented. Two species are recognized within Paramachaerodus, Pa. orientalis, and Pa. maximiliani, and the genus Promegantereon Kretzoi, 1938 is retrieved to include Promegantereon ogygia. Material from the Turolian Spanish localities of Crevillente-2 (MN 11, Alicante) and Las Casiones (MN 13, Teruel), which was previously assigned to Paramachaerodus, is now included in the tribe Metailurini. The exceptional discoveries at the Spanish Vallesian (MN 10, Madrid) fossil site of Batallones-1 have made it possible to characterize the dentition and cranial anatomy of a previously very poorly known mac…
Large herbivore population and vegetation dynamics 14,600–8300 years ago in central Latvia, northeastern Europe
2019
Abstract This study seeks to explain how the large herbivore (large vertebrate, megafauna – terrestrial taxa with adults > 45 kg) population density changed during abrupt postglacial climate and environmental change. The Lateglacial and Early Holocene (14,600–8300 years ago) were represented by various environmental and climate changes and a transition from a cold to a warm climate, with subsequent changes in flora and fauna. Using Lake Āraisi as a case study (Latvia, northeastern Europe), local to regional vegetation was reconstructed by analyzing plant macroremains and pollen from the lake sediment profile. Here, we present the first dung fungus spore-based qualitative reconstruction of l…
Towards European Dimensions of City Resilience
2016
International audience; Disaster resilience is becoming more important and raises the highest concerns worldwide, including in Europe. Cities have a vital role for resilience because a majority of the population resides in the cities. Despite the recognition of the importance of city resilience, there is no strong consensus what city resilience is and its dimensions, and how the resilience concept should be transferred into management practice in the cities. In this paper, we conduct a survey of EU sectorial approaches in terms of EU-funded projects related to climate change and critical infrastructure, where urban or city resilience are in focus. The goal is to obtain an overview of how th…
SPECIES RICHNESS WITHIN FAMILIES OF FLOWERING PLANTS
1994
Variation in species and genus richness among families of flowering plants was examined with respect to four classification variables: geographical distribution, growth form, pollination mode, and dispersal mode. Previous studies have estimated rates of species proliferation from age and contemporary diversity. Here we found that the earliest appearances in the fossil record are correlated with contemporary familial species richness, abundance in the fossil record, and the independent variables considered in this analysis. Thus, we believe that the fossil record does not provide reasonable estimates of the ages of families and that the rate of species proliferation cannot be calculated from…
Survival and gene expression under different temperature and humidity regimes in ants
2017
Short term variation in environmental conditions requires individuals to adapt via changes in behavior and/or physiology. In particular variation in temperature and humidity are common, and the physiological adaptation to changes in temperature and humidity often involves alterations in gene expression, in particular that of heat-shock proteins. However, not only traits involved in the resistance to environmental stresses, but also other traits, such as immune defenses, may be influenced indirectly by changes in temperature and humidity. Here we investigated the response of the ant F. exsecta to two temperature regimes (20 degrees C & 25 degrees C), and two humidity regimes (50% & 75%), for…