Search results for "Study"
showing 10 items of 15483 documents
CHANGES IN COLLEMBOLA RICHNESS AND DIVERSITY ALONG A GRADIENTOF LAND-USE INTENSITY : A pan European study
2006
Changes in Collembola richness and diversity along a land-use intensity gradient were studied in eight European countries (Portugal, Spain, France, Switzerland, Hungary, UK, Ireland and Finland). In each country a set of six 1 km2 land-use units (LUUs) were selected forming a gradient ranging from natural forest to agricultural dominated landscapes, passing through mixed-use ones. In addition to data on Collembola, detailed information regarding landscape diversity and structure was collected for each LUU. A total of 47,774 individuals were identified from 281 species. Collembola reacted not only to changes in the diversity of the landscape, but also to the composition of that diversity and…
Abundance patterns at the invasion front: The case of Siganus luridus in Linosa (Strait of Sicily, Central Mediterranean Sea)
2017
The dusky spinefoot (Siganus luridus) has spread through much of the eastern Mediterranean since its introduction in 1920. In the present study, we monitored the abundance of this invader around the island of Linosa (Strait of Sicily), where the species was first recorded in 2003. Data were periodically collected along two temporal windows, 2005–06 and 2012–15, by both underwater visual census and surface snorkelling. Local ecological knowledge was investigated to gain complementary information. Both approaches highlighted significant proliferation of this tropical invader, with an average abundance of 0.36 individuals per 250m2 across the 0–30-m depth range. Dense aggregations of more than…
Extended haplodiploidy hypothesis
2019
P.R., M.P., and H.H. were supported by Academy of Finland (grant 258385 to M.P., grant 135970 to H.H., and 252411 to the Centre of Excellence in Biological Interactions), P.R. also by the Royal Society Newton International Fellowship, and H.H. also by the Kone Foundation. Evolution of altruistic behavior was a hurdle for the logic of Darwinian evolution. Soon after Hamilton formalized the concept of inclusive fitness, which explains how altruism can evolve, he suggested that the high sororal relatedness brought by haplodiploidy could be why Hymenopterans have a high prevalence in eusocial species, and why helpers in Hymenoptera are always female. Later it was noted that in order to capitali…
Brown trout (Salmo trutta L.) high genetic diversity around the Tyrrhenian Sea as revealed by nuclear and mitochondrial markers
2018
The brown trout (Salmo trutta L.) is widely distributed all around Europe but its natural diversity is threatened by massive stocking with Atlantic domestic strains. Describing the remaining natural genetic diversity and the proportion of domestic hatchery strains in rivers is a prerequisite for smart conservation. The high genetic diversity of brown trout populations around the Tyrrhenian Sea is well known. Use of twelve microsatellites has allowed description of the natural genetic structure of populations and detection of the consequences of stocking. Mitochondrial DNA control region sequences and the LDH-C1* gene enabled placement of each population into one of the six mitochondrial and…
The consequences of size-selective fishing mortality for larval production and sustainable yield in species with obligate male care
2020
AbstractSize-based harvest limits or gear regulations are often used to manage fishing mortality and ensure the spawning biomass of females is sufficiently protected. Yet, management interactions with species’ mating systems that affect fishery sustainability and yield are rarely considered. For species with obligate male care, it is possible that size-specific harvest of males will decrease larval production. In order to examine how size-based management practices interact with mating systems, we modeled fisheries of two species with obligate care of nests, corkwing wrasse (Symphodus melops, Labridae) and lingcod (Ophiodon elongatus, Hexigrammidae) under two management scenarios, a minimum…
First record for the flora of Italy and lectotypification of the name Linum elegans (Linaceae)
2017
Linum elegans has been detected in calcareous rocky garrigues on the Gargano promontory (Apulia, SE-Italy), representing the first record for the Italian flora and the first one outside the Balkan Peninsula. The geographical disjunction may provide evidence for past amphi-Adriatic/amphi-Ionic terrestrial connections. The population found was ascribed to L. campanulatum in the past. As a consequence, a comparison between these two species is undertaken. Furthermore, the name L. elegans is here lectotypified on a specimen preserved at G, and the IUCN assessment of the species in Italy is briefly discussed.
Eimeria-parasites are associated with a lowered mother's and offspring's body condition in island and mainland populations of the bank vole.
2006
This study, based on correlative data, tests the hypothesis that infections withEimeriaspp. parasites exert a significant loss of fitness of bank voles (Clethrionomys glareolus) reflected in lower reproductive success and survival, declining host population densities and are associated positively with population size. The study was conducted in 20 mainland and 27 island populations in central Finland during May–September in 1999. Faecal samples showed that 28% of 767 individuals were infected withEimeriaspp. The presence ofEimeriaparasites was higher in dense mainland populations than in sparsely populated islands. Eimerian infections increased during the course of the breeding season, prob…
The Bruce effect revisited: is pregnancy termination in female rodents an adaptation to ensure breeding success after male turnover in low densities?
2017
Pregnancy termination after encountering a strange male, the Bruce effect, is regarded as a counterstrategy of female mammals towards anticipated infanticide. While confirmed in caged rodent pairs, no verification for the Bruce effect existed from experimental field populations of small rodents. We suggest that the effect may be adaptive for breeding rodent females only under specific conditions related to populations with cyclically fluctuating densities. We investigated the occurrence of delay in birth date after experimental turnover of the breeding male under different population composition in bank voles (Myodes glareolus) in large outdoor enclosures: one-male–multiple-females (n = 6 p…
Geographical trends in the yolk carotenoid composition of the pied flycatcher (Ficedula hypoleuca).
2010
Carotenoids in the egg yolks of birds are considered to be important antioxidants and immune stimulants during the rapid growth of embryos. Yolk carotenoid composition is strongly affected by the carotenoid composition of the female’s diet at the time of egg formation. Spatial and temporal differences in carotenoid availability may thus be reflected in yolk concentrations. To assess whether yolk carotenoid concentrations or carotenoid profiles show any large-scale geographical trends or differences among habitats, we collected yolk samples from 16 European populations of the pied flycatcher, Ficedula hypoleuca. We found that the concentrations and proportions of lutein and some other xantho…
Diversifying selection on MHC class I in the house sparrow (Passer domesticus).
2009
10 pages; International audience; Genes of the major histocompatibility complex (MHC) are the most polymorphic loci known in vertebrates. Two main hypotheses have been put forward to explain the maintenance of MHC diversity: pathogen-mediated selection and MHC-based mate choice. Host-parasite interactions can maintain MHC diversity via frequency-dependent selection, heterozygote advantage, and diversifying selection (spatially and/or temporally heterogeneous selection). In this study, we wished to investigate the nature of selection acting on the MHC class I across spatially structured populations of house sparrows (Passer domesticus) in France. To infer the nature of the selection, we comp…