Search results for "Danger"
showing 10 items of 264 documents
Measurement and Conservation of Species and Habitat Biodiversity at Different Scales on Small Mediterranean Islands
2021
In this paper we discuss current methodologies for measuring biodiversity, analyse pros and cons at different scales, and finally propose distribution mapping as the most suitable method for measuring floristic biodiversity on small Mediterranean islands. These territories often host endangered flora and habitats, and have peculiarities that distinguish them from the mainland and the larger islands.
Genetic diversity in Cytisus aeolicus Guss. (Leguminosae), a rare endemite of the Italian flora
1998
ABSTRACT Cytisus aeolicus Guss, is an endemic plant restricted to the isles of Vulcano, Stromboli and Alicudi in the Aeolian archipelago. All known populations were assayed for genetic variability using enzyme polymorphism. Allozyme variation at 16 loci coding for 10 enzyme systems was examined. The great majority of loci turned out to be monomorphic or fixed heterozygous. The observed genetic depauperation is indicative of historical factors, such as the bottleneck effect associated with migration, and the founder effect in population re-establishment. The low genetic diversity is largely partitioned within rather than among populations, indicating that extant populations have not been est…
A report on the conservation status of segetal weeds in Tajikistan
2014
Summary Intensification of agriculture has significantly diminished the populations of segetal weeds worldwide in recent decades. Remarkable changes to the entire flora and vegetation of man-made habitats are being observed in agroecosystems. The present study analyses, for the first time, the threat status of segetal weeds in Tajikistan. A group of 871 weed species were evaluated against IUCN criteria. The assessment of threat status revealed that 214 weed taxa have to be regarded as threatened in Tajikistan, including 18 endemic and four subendemic plants. Five species have been classified as extinct, 27 as critically endangered, 27 as endangered, 39 as vulnerable, 34 as near threatened a…
The contribution of forest restoration to the conservation of woody endangered species in Sicily
2017
Sicilian forest ecosystems are, in general, numerically poor in terms of their floristic composition. As many studies on Sicilian dendroflora have highlighted, such poorness is not intrinsic to forest formations, but it is due to the millenary human pressures. Repeated passage of fire, continuous wood usage and reforestations by single or few species dra- matically reduced the plant biodiversity of Sicilian forest ecosystems, often suffering of monodominance. The Sicilian dendroflora includes several endangered species, such as Abies nebrodensis, Betula aetnensis, Celtis tournefortii subsp. asperrima and subsp. aetnensis, as the wild pears, which in Sicily are represented by 4 endemic speci…
Parasites in sympatric populations of native and invasive freshwater bivalves
2021
An increasing threat to local, native freshwater mussels (Unionida)—an ecologically important but globally alarmingly declining group— is the invasion by exotic bivalves. The Enemy Release Hypothesis predicts that introduced species should benefit from enemy-mediated competition because they are less likely to be harmed by natural enemies, such as parasites, than their native competitors. We investigated within-site differences in parasitism between sympatric native (tot. five spp.) and invasive (tot. three spp.) bivalves in eight northern European waterbodies, which harboured totally 15 parasite taxa. In paired comparisons using within-site averages, the mean number of parasite species in …
Analysis of population genetic structure and variability using RAPD markers in the endemic and endangered Limonium dufourii (Plumbaginaceae)
1998
Limonium dufourii (Plumbaginaceae) is a triploid species, with apomictic reproduction, endemic to the east mediterranean coast of Spain, where it is present in only six populations with a few individuals in most of them. L. dufourii is included in the Red List of Endangered Species by the IUCN. Genetic variation and population structure in this species has been studied using RAPDs. Twelve different primers provided 124 reliable bands of which 33 were polymorphic among the 165 individuals analysed. Those polymorphic bands were able to define 44 different patterns, of which all but six were present in only one population. Several methods for statistical evaluation have been used for intra- an…
Genetic diversity ofNarcissus tortifolius, an endangered endemic species from Southeastern Spain
2015
AbstractIn this work, we analyzed inter-simple sequence repeat markers from 10 populations (298 individuals) spanning the whole distribution range of the endemic Narcissus tortifolius. We assessed genetic variation levels and distribution by estimates of genetic diversity, analysis of molecular variance (AMOVA), principal coordinates and Bayesian methods. N. tortifolius showed moderate genetic diversity at intrapopulation level and low genetic differentiation of populations. In general, Almerian populations showed slightly higher levels of genetic diversity than Murcian populations. Our results indicate that habitat fragmentation has not caused genetic depauperation in N. tortifolius but di…
Genetic variations in the endangered Sicilian endemic Brassica rupestris: proposals for a conservation strategy
2012
Brassica rupestris Raf. is a chasmophyte species that includes two subspecies, both endemic to Central-Western Sicily (Italy). Inter-Simple Sequence Repeat (ISSR) markers were used to detect genetic diversity within and among eight populations representative of the species' distribution range. High levels of genetic diversity were revealed both at the population (PPB = 53.88%, HS = 0.212, Sh = 0.309) and at the species level (PPB = 96.55%, HT = 0.307, Sh = 0.464). The correlation between genetic and geographical distances was negative (Mantel test, r = -0.06, P < 0.95). The two subspecies of B. rupestris, subsp. rupestris and subsp. hispida, showed remarkable genetic similarity and molec…
Isolation and biodiversity inCytisus villosusPourret (Fabaceae, Genisteae): enzyme polymorphism in disjunct populations
1997
ABSTRACT The genetic diversity of isolated populations of Cytisus villosus has been studied by means of enzyme polymorphism analysis. Two types of isolated populations were studied: “terrestrial islands” in Sicily, and “true islands” in the Aeolian archipelago. In the populations of “true islands” the number of alleles and the heterozygosity are lower than in “terrestrial islands”. Isolation amongst Sicilian populations seems to be more recent than isolation of the Aeolian populations, and may be attributed to climatic changes which occurred during the Holocene and/or to human activities. The disjunction of the Aeolian populations seems much more recent than the origin of the isles themselv…
Characterization of 10 trinucleotide microsatellite loci in the Critically Endangered Pyrenean yam Borderea chouardii (Dioscoreaceae)
2003
The low levels of allozymic variability found in the Critically Endangered Borderea chouardii prompted us to develop microsatellite markers to assess the genetic variability and population structure for the adequate conservation management of this species. A (CTT) n enriched partial genomic library was constructed. Ten polymorphic microsatellite loci were isolated from it, rendering 51 alleles in 47 individuals analysed. The allelic pattern observed for all of the loci with more than two alleles suggests that B. chouardii is tetraploid.