Search results for "POPULATION"
showing 10 items of 9945 documents
The phylogeny and biogeography of Gentiana L. sect. Ciminalis (Adans.) Dumort.: A historical interpretation of distribution ranges in the European hi…
1998
Abstract Gentiana sect. Ciminalis consists of seven mostly ecologically or geographically vicariant and closely related species which are distributed throughout the South and Central European high mountains. The analysis of a RAPD data set and trn L-intron and ITS sequences resulted in slightly different phylogenetic hypotheses. In the preferred hypothesis the group consists of two completely resolved main lineages: 1) G. clusii and G. alpina. 2) G. dinarica, G. acaulis, G. ligustica, G. angustifolia and G. occidentalis. The most important conclusions we have drawn from this phylogenetic hypothesis and from the observed patterns of molecular variation are: 1) The calcifuge ecology of G. aca…
A potential role for water in the modulation of oxygen-binding by tarantula hemocyanin
2003
Hemocyanin from the tarantula Eurypelma californicum is a large respiratory protein with an exceptional high cooperativity. In contrast to hemocyanins from other species, no physiological allosteric effectors other than protons have been identified so far for this 24-meric oligomer. Here we report for the first time the mediating effects of water activity on the oxygen binding properties of a hemocyanin. Oxygen binding curves were measured in presence of several concentrations of glycine and sucrose since both substances reduce water activity. A pronounced shift of the p(50) was observed in both cases but in different directions: adding sucrose shifts the p(50) towards lower values whereas …
The Role of Emigration in Foreign Aid Policies: The Case of Spain and Morocco. LE RÔLE DE LA MIGRATION DANS LES POLITIQUES D'AIDE EXTÉRIEURE. LE CAS …
2008
This article analyses the relationships between emigration and Official Development Aid (ODA) policies, taking the cases of Spain and Morocco as the backdrop to the study. It discusses the principal characteristics of both the Spanish state and non-governmental cooperation in Morocco, the underlying motivations of the principal stakeholders, and the way international cooperation policies now encompass the phenomenon of emigration. The paper compares the field of co-development, which encompasses a rather limited understanding of immigration, with ODA policies, in which immigration is an increasingly important agenda item for both the central government and the Spanish autonomous communities…
Aging on Indian Reservations: The Ugly, the Bad, and the Good
2012
This chapter examines the conditions for the older population on Indian reservations and how those conditions compare to the non-Indian population. The discussion opens on a national level, though the focus is on tribes in the Western United States. Older Indians on reservations are aging in a society where they are an almost invisible part of rural America. Yet the reservations, despite the poor socioeconomic conditions on many, represent home and a place for off-reservation Native Americans to come back to. To include the voices of Indian elders and gain insights into how they perceive being elders, we report on interviews conducted with older Indians on the Nez Perce reservation in Idaho…
Reproductive biology and conservation implications of three endangered snapdragon species (Antirrhinum, Plantaginaceae)
2009
About 32% of Antirrhinum species are considered to be endangered; however, no field studies have focused on their reproductive biology. In this work, several aspects of the reproductive biology (flowering phenology, floral biology, breeding system) and potential limits on seed quantity and quality (pollen limitation, inbreeding depression) were studied in natural populations of three endangered species of the genus (Antirrhinum charidemi, Antirrhinum subbaeticum, Antirrhinum valentinum). Results disclose that all three species need insect visitors for seed production since fruit set after autonomous self-pollination was lower than under hand cross-pollination. A. charidemi and A. valentinum…
Pollination: An Integrating Factor of Biocenoses
1991
A survey is given of the ecological constraints which affect the process of pollen transfer — and hence the gene flow — within a biocenosis. Wind pollination (anemophily) plays a dominant role in species-poor communities only. The quantity of zoophilous species increases equator-ward to up to 100 % and so does the degree of integration in animal-plant interactions. Biotic pollination is pinpointed. Manifoldness and specifity of methods reduce pollen waste and mispollinations. Saturated ecosystems dispose of a complete set of pollination syndromes and the respective pollinator guilds, narrow niche widths, a high percentage of eutropic flowers, shorter flowering times, and a temporal and spat…
Toward Anticancer Immunotherapeutics: Well-Defined Polymer-Antibody Conjugates for Selective Dendritic Cell Targeting
2014
This paper describes the synthesis of semitelechelic maleimide-modified N-(2-hydroxypropyl)methacrylamid) (HPMA) based polymers of narrow dispersity that can be conjugated e.g. to anti-DEC-205 antibodies affording "star-like" topologies (one antibody decorated with several polymer chains). FCS revealed a hydrodynamic diameter of R(h) = 7.9 nm and SEC narrow dispersity (1.45). Primary in vitro studies with bone marrow derived dendritic cells (DC) show higher cellular binding and uptake rates compared to control samples. Moreover, incubating these conjugates to primary splenocytes demonstrates a much higher affinity to the primary DCs than to any other immune cell population within the splee…
Growth and production of three macrozoobenthic species in the Gulf of Riga, including comparisons with other areas
1999
Three soft-bottom stations in the southern part of the Gulf of Riga were studied during the period December 1993 to January 1995. The amphipods, Monoporeia affinis and Pontoporeia femorata, and the poychaete Marenzelleria viridis, were analysed for production, using the cohort growth method. Animals were also analysed for carbon and nitrogen content in a CHN-analyser. Based on size measurements, the quantitative data were divided into age-classes and the growth of each cohort was calculated first as wet weight and then converted into carbon and nitrogen content. Total annual production of each species was calculated as well as turnover ratios. The turnover ratio for Monoporeia affinis was e…
Population dynamics and tolerance to desiccation in a crustacean ostracod adapted to life in small ephemeral water bodies
2011
AbstractGiven their small size, isolation and unpredictability, temporary rockpools present high environmental stress and impoverished communities of species that have adapted to such stressful conditions. Special adaptations of the invertebrates living in these habitats include tolerance to desiccation and fast ontogenetic development in order to maintain stable populations and face high risk of extinction. Dozens of small rockpools (mostly with Ø<1m) can be found in east Spain on limestone substrate, where the only known Iberian populations of Heterocypris bosniaca Petkovski et al. (2000), an ostracod species with geographic parthenogenesis, have been recently found. In this survey, two o…
Factors influencing the extent of inbreeding depression: an example from scots pine
1999
Detailed studies suggest that the level of inbreeding depression may vary between populations. In a study of Scots pine from Finland, the level of inbreeding depression was much lower in northern than in southern populations. We have examined theoretically whether population genetic factors, such as the level of selfing, intensity of selection against heterozygotes or homozygotes, level of mutation, a bottleneck, finite population size, or the level of polyembryony could account for this difference. Higher selfing or stronger selection against heterozygotes in the north, both at biologically reasonable levels, appear to produce changes consistent with the observed differences and we conside…