Search results for "Population Size"
showing 10 items of 143 documents
Populations of breeding birds in Byers Peninsula, Livingston Island, South Shetland Islands
2013
Data about breeding populations of birds in the Antarctica are rare and fragmented. Thus, information about the status of the breeding populations of Antarctic birds is crucial given the current scenario of climate change, which is particularly acute in Antarctica. This paper presents new information about the populations of the Antarctic tern Sterna vittata, the kelp gull Larus dominicanus, the southern giant petrel Macronectes giganteus, the Antarctic skua Catharacta antarctica lonnbergi, the chinstrap penguin Pygoscelis antarctica and the gentoo penguin Pygoscelis papua on Byers Peninsula (Livingston Island, South Shetland Islands). We used line transects counts to estimate both densitie…
The EUROCARE-5 study on cancer survival in Europe 1999-2007: Database, quality checks and statistical analysis methods
2015
Abstract Background Since 25 years the EUROCARE study monitors the survival of cancer patients in Europe through centralised collection, quality check and statistical analysis of population-based cancer registries (CRs) data. The European population covered by the study increased remarkably in the latest round. The study design and statistical methods were also changed to improve timeliness and comparability of survival estimates. To interpret the EUROCARE-5 results on adult cancer patients better here we assess the impact of these changes on data quality and on survival comparisons. Methods In EUROCARE-5 the survival differences by area were studied applying the complete cohort approach to…
Insights into Genetic Diversity, Runs of Homozygosity and Heterozygosity-Rich Regions in Maremmana Semi-Feral Cattle Using Pedigree and Genomic Data
2020
Semi-feral local livestock populations, like Maremmana cattle, are the object of renewed interest for the conservation of biological diversity and the preservation and exploitation of unique and potentially relevant genetic material. The aim of this study was to estimate genetic diversity parameters in semi-feral Maremmana cattle using both pedigree- and genomic-based approaches (FIS and FROH), and to detect regions of homozygosity (ROH) and heterozygosity (ROHet) in the genome. The average heterozygosity estimates were in the range reported for other cattle breeds (HE=0.261, HO=0.274). Pedigree-based average inbreeding (F) was estimated at 4.9%. The correlation was low between F and genomi…
Fish population size, and not density, as the determining factor of parasite infection: a case study.
2004
The diversity and abundance of parasites vary widely among populations of the same host species. These infection parameters are, to some extent, determined by characteristics of the host population or of its habitat. Recent studies have supported predictions derived from epidemiological models regarding the influence of host population density: parasite abundance and parasite species richness are expected to increase with increasing host population density, at least for directly transmitted parasites. Here, we test this prediction using a natural system in which populations of the crucian carp, Carassius carassius (L.), occur alone, with no other fish species, in a series of 9 isolated pond…
Conservation genetics of an endemic from the Mediterranean Basin: high genetic differentiation but no genetic diversity loss from the last population…
2013
The Mediterranean Basin is a biodiversity hotspot, housing > 11.000 narrowly endemic plant species, many of which are declining due to mass tourism and agricultural intensification. To investigate the genetic resource impacts of ongoing habitat loss and degradation, we characterized the genetic variation in the last known populations of Leopoldia gussonei, a self-compatible endangered Sicilian Grape Hyacinth numbering less than 3,000 remaining individuals, using AFLP. Results demonstrated significant genome-wide genetic differentiation among all extant populations (I broken vertical bar(ST) = 0.05-0.56), and genetic clustering according to geographic location. Gene diversity was fairly c…
Patterns of genetic and phenotypic variation in Iris haynei and I. atrofusca (Iris sect. Oncocyclus = the royal irises) along an ecogeographical grad…
2002
Iris haynei and I. atrofusca are two closely related narrow endemics distributed vicariously along an ecogeographical north-south gradient in Israel and the West Bank. To obtain baseline information of the taxonomic status, conservation and population history of these taxa, we investigated patterns of phenotypic variation and the partitioning of genetic variation within and among populations using dominant random amplified polymorphic DNA (RAPD) markers. Multivariate (principal components analysis) and taxonomic distance analyses based on morphometric traits from eight populations revealed no unambiguous separation into two distinct groups. Results of genetic analyses for nine populations d…
Phylogenetic relationships, evolutionary origin, taxonomic status, and genetic structure of the endangered local Lower Elbe river (Germany) endemic O…
2005
Abstract Oenanthe conioides is an endangered local endemic of the Lower Elbe river region in Germany where it is found in areas with freshwater tides. Internal transcribed spacer (ITS) and amplified fragment length polymorphism (AFLP) markers were used to investigate its phylogenetic relationships, evolutionary origin, taxonomic status, and genetic structure. Oe. conioides is most closely related to Oe. aquatica and Oe. fluviatilis, and cannot be distinguished from Oe. aquatica by ITS sequence variation. Oe. aquatica is found mainly in standing or slow-flowing freshwater habitats. The AFLP analysis indicated that Oe. conioides may constitute a monophyletic lineage nested within Oe. aquatica…
Decreased sexual signalling reveals reduced viability in small populations of the drumming wolf spider Hygrolycosa rubrofasciata.
2004
One of the important goals in conservation biology is to determine reliable indicators of population viability. Sexual traits have been suggested to indicate population extinction risk, because they may be related to viability through condition dependence. Moreover, condition-dependent sexual traits may be more sensitive indicators of population viability than early life-history traits, because deleterious fitness effects of inbreeding tend to be expressed mainly at the end of the species' life history. However, empirical evidence of the significance of sexual behaviour for population viability is missing. In this study, we examined two male sexual traits and survival in 39 different-sized …
Thresholds for impaired species recovery
2015
Studies on small and declining populations dominate research in conservation biology. This emphasis reflects two overarching frameworks: the small-population paradigm focuses on correlates of increased extinction probability; the declining-population paradigm directs attention to the causes and consequences of depletion. Neither, however, particularly informs research on the determinants, rate or uncertainty of population increase. By contrast, Allee effects (positive associations between population size and realized per capita population growth rate, r realized , a metric of average individual fitness) offer a theoretical and empirical basis for identifying numerical and temporal threshol…
Quality of life ranking of Spanish cities: A non-compensatory approach
2021
Abstract Urban areas are hubs of economic activity, but also consumption centers where a high quality of life may attract human capital and increase prospects of economic growth and well-being. We rank 73 Spanish cities on the basis of 35 individual indicators covering three basic facets of quality of life: socio-economic performance, general livability conditions, and residents' health status. We reject the conventional approach of compensability among different quality of life dimensions in favor of a Condorcet-inspired non-compensability approach. We obtain three partial composite indicators, one for each of the aforementioned dimensions, and a global indicator that synthesizes the three…