Search results for "Extinction"

Effects of fragmented breeding habitat and resource distribution on behavior and survival of the bank vole ( Myodes glareolus )

2010

Habitat fragmentation causes negative population trends or even local extinction in many species. Understanding the role of fragmentation on behavior and space use of animals is an essential part of revealing the mechanism behind observed population declines. We studied experimentally the effects of small-scale habitat fragmentation on the distribution and movement of bank voles (Myodes glareolus) in seminatural enclosures. We predicted that besides habitat structure, availability of two resources, food for both sexes, and receptive females for males, determine individual distribution. We manipulated female density (either 0, 4, or 12 per enclosure) and followed movements of radio-collared …

Origination and extinction patterns of mammals in three central Western Mediterranean islands from the Late Miocene to Quaternary

2008

Abstract An overview of the population histories of three insular realms (Gargano palaeo-archipelago, Sardinia–Maritime Tuscany palaeo-bioprovince and the Sicilian insular complex) during the Late Miocene and Quaternary are here presented. The complexity of biodiversity changes in the islands is analysed to propose an interpretation of origination and extinction patterns. The study highlighted several important aspects of insular faunas. Evolutionary radiations were found to contribute significantly only to the Gargano faunal diversity, likely because the area was an archipelago at the time. Another interesting result is that large and small mammals do not disperse and become extinct all at…

End-Triassic Extinction in a Carbonate Platform From Western Tethys: A Comparison Between Extinction Trends and Geochemical Variations

2022

The Triassic/Jurassic boundary section cropping out at Mt Sparagio in north-western Sicily (Italy) consists of a thick and continuous peritidal succession typical of a Tethyan carbonate platform. The combined chemostratigraphic and biostratigraphic study of this section allowed us to parallel the environmental variations inferred by the isotopic records and the extinction trends recorded by the benthic organisms. In the studied section, the isotope data of C, O, and S are indicative of serious environmental perturbations related to the Central Atlantic Magmatic Province (CAMP) activity, as recorded worldwide. Two negative excursions in the C-curve (Initial-CIE and Main-CIE) confirm the acid…

Taxonomy and conservation in Higher Plants and Bryophytes in the Mediterranean Area

2015

The Mediterranean Region is among the areas of the world richest in wild and cultivated taxa. Extinctions in the Mediterranean area are bound to have occurred in historical times but they are not documented. The probable and documented cases of plant extinction in specific areas within the Mediterranean are equivalent to 0.25% of total species-by-area records. Species with a large range are more prone to local population size fluctuations and eventual extinction than species with a reduced population. Small islands floras are more prone to extinction than those on large islands and on the mainland. Reliability of our data on Mediterranean plant extinctions is poor. New emphasis on floristic…

Tutela antidiscriminatoria: el principio de igualdad y el derecho a la no discriminación por razón de sexo en las relaciones laborales

2016

Effects of Hippocampal State-Contingent Trial Presentation on Hippocampus-Dependent Nonspatial Classical Conditioning and Extinction

2014

Hippocampal local field potentials are characterized by two mutually exclusive states: one characterized by regular θ oscillations (∼4–8 Hz) and the other by irregular sharp-wave ripples. Presenting stimuli during dominant θ oscillations leads to expedited learning, suggesting that θ indexes a state in which encoding is most effective. However, ripple-contingent training also expedites learning, suggesting that any discrete brain state, much like the external context, can affect learning. We trained adult rabbits in trace eyeblink conditioning, a hippocampus-dependent nonspatial task, followed by extinction. Trials were delivered either in the presence or absence of θ or regardless of hippo…

"Save Private Pinna !" The Mediterranean fan mussel, a patrimonial bivalve, is in serious danger of extinction.

2019

Pinna nobilis is the largest bivalve in the Mediterranean Sea. This endemic species lives in the Posidonia meadows,in the form of small sparse populations. It is a heritage species: its byssus has long been collected to be wovenand used to make gloves, hats or stoles. Protected by a European Directive (1992), P. nobilis is closely monitored,nationally and internationally. But since the end of 2016, an epidemic, which origin seems to be a protozoan parasite,decimates populations (up to 100% mortality). This event began on the Spanish coast and spreads now all around theMediterranean. Although conservation measures have been taken, the next few years could see the extinction of thisemblematic…

HAQ survey: red QSO candidates follow-up

2015

Quasi-stellar objects (QSOs) whose spectral energy distributions (SEDs) are reddened by dust either in their host galaxies or in intervening absorber galaxies are to a large degree missed by optical color selection criteria like the ones used by the Sloan Digital Sky Survey (SDSS). To overcome this bias against red QSOs, we employ a combined optical and near-infrared (near-IR) color selection. In this paper, we present a spectroscopic follow-up campaign of a sample of red candidate QSOs which were selected from the SDSS and the UKIRT Infrared Deep Sky Survey (UKIDSS). The spectroscopic data and SDSS/UKIDSS photometry are supplemented by mid-infrared photometry from the Wide-field Infrared S…

Conservation of threatened habitat types under future climate change – Lessons from plant-distribution models and current extinction trends in southe…

2015

A higher risk of future range losses as a result of climate change is expected to be one of the main drivers of extinction trends in vascular plants occurring in habitat types of high conservation value. Nevertheless, the impact of the climate changes of the last 60 years on the current distribution and extinction patterns of plants is still largely unclear. We applied species distribution models to study the impact of environmental variables (climate, soil conditions, land cover, topography), on the current distribution of 18 vascular plant species characteristic of three threatened habitat types in southern Germany: (i) xero-thermophilous vegetation, (ii) mesophilous mountain grasslands (…

Contemporary spatial and environmental factors determine vascular plant species richness on highly fragmented meadows in Central Finland

2018

Context Habitat loss is a major threat to biodiversity. It can create temporal lags in decline of species in relation to destruction of habitat coverage. Plant species specialized in semi-natural grasslands, especially meadows, often express such extinction debt. Objectives We studied habitat loss and fragmentation of meadows and examined whether the changes in meadow coverage had caused an extinction debt on vascular plants. We also studied whether historical or present landscape patterns or contemporary environmental factors were more important determinants of species occurrence. Methods We surveyed the plant species assemblages of 12 grazed and 12 mown meadows in Central Finland and dete…