Search results for " rat"

Density and reproductive characteristics of female brown bears in the Cantabrian Mountains, NW Spain

2018

Here we present annual nearest-neighbour distances (as a proxy of density) between females with cubs-of-the-year (hereafter FCOY) and reproductive characteristics of brown bears Ursus arctos in the Cantabrian Mountains (NW Spain), from 1989 to 2017. FCOY nearest-neighbour distances and reproduction parameters of 19 focal females followed over several consecutive years (from 2004 to 2017) were obtained from bears inhabiting the western sector of the Cantabrian Mountains, where most of the bear population resides. In contrast, general reproductive characteristics were studied in the whole Cantabrian Mountains (western and eastern sectors together) on a sample of 362 litter sizes and 695 cubs.…

Epizooic ciliates (Vorticella sp.) compete for food with their host Daphnia longispina in a small polyhumic lake.

1987

Clearance rates of epizooic ciliates (Vorticella sp.) were measured together with their host, a planktonic cladoceran Daphnia longispina by using fluorescent latex beads as tracers of food. Vorticellans and their host graze on food of same size range (nanoplanktonic algae and bacteria). Individual clearance rates of Vorticella averaged 6.9 and 7.0 μl ind-1 h-1 and those of Daphnia 463 and 708 μl ind-1 h-1 for beads with diameter 2.00 and 3.92 μm. On the average, epizooic vorticellans together on the carapace of Daphnia cleared particles with rates representing 25–33% of that the host cleared, the maximum rates being 50–80%. In a steeply stratified polyhumic lake vorticellans take advantage …

Local Recruitment in the Greater Flamingo: A New Approach Using Capture- Mark-Recapture Data

1997

International audience; Although the establishment of new individuals in the breeding component of a population is an essential feature of population regulation, only a few attempts have been made to test biological hypotheses about recruitment. Most previous studies rely on ad hoc calculations or are flawed with unwarranted assumptions about survival. We use a recently developed approach, based on capture-mark-recapture, in which analysis of local recruitment is similar to a time-reversed analysis of survival. The basic data set consists of capture histories viewed in reverse order, with initial capture at year of birth, and subsequent observations corresponding to years when the animal ha…

Spatial variability of stable carbon and nitrogen isotope ratios in a Mediterranean coastal lagoon

2005

Exploring the trophic pathway of organic matter within the Mauguio lagoon (southern France, western Mediterranean), we found spatial differences in the isotopic composition (both δ13C and δ15N values) of organic matter sources (primary producers, particulate and sedimentary organic matter), which were mirrored in the upper trophic levels (invertebrates and fish). On average, δ13C was heavier by about 1.5–2‰ in the location under marine influence than in the sites influenced by freshwater discharge. The opposite trend was found for δ15N, which attained maximum values in the north-central zone influenced by freshwater delivery. For both C and N stable isotope ratios, the highest spatial varia…

Terrestrial organic matter quantity or decomposition state does not compensate for its poor nutritional quality for Daphnia

2019

2018

The Atlantic surfclam (Spisula solidissima) is a commercially important species in North American waters, undergoing biological and ecological shifts. These are attributed, in part, to environmental modifications in its habitat and driven by climate change. Investigation of shell growth patterns, trace elements, and isotopic compositions require an examination of growth lines and increments preserved in biogenic carbonates. However, growth pattern analysis of S. solidissima is challenging due to multiple disturbance lines caused by environmental stress, erosion in umbonal shell regions, and constraints related to sample size and preparation techniques. The present study proposes an alternat…

The evolutionary dynamics of adaptive virginity, sex-allocation, and altruistic helping in haplodiploid animals

2017

In haplodiploids, females can produce sons from unfertilized eggs without mating. However, virgin reproduction is usually considered to be a result of a failure to mate, rather than an adaptation. Here, we build an analytical model for evolution of virgin reproduction, sex-allocation, and altruistic female helping in haplodiploid taxa. We show that when mating is costly (e.g., when mating increases predation risk), virginity can evolve as an adaptive female reproductive strategy. Furthermore, adaptive virginity results in strongly divergent sex-ratios in mated and virgin queen nests ("split sex ratios"), which promotes the evolution of altruistic helping by daughters in mated queen nests. H…

The ormer (Haliotis tuberculata): A new, promising paleoclimatic tool

2015

International audience; This study aimed to investigate the environmental controls on the oxygen isotope composition of shells of the European abalone, Haliotis tuberculata. Seasonal delta O-18 profiles from the outer prismatic layer of four abalone shells, collected live in northwest Brittany (France) in 2002 and 2012, were compared to local temperatures and salinities. According to the findings herein, delta O-18 variations in abalone shells corresponded to seasonal variations, and thus, shell composition represented a reliable tool for aging and growth studies. Seawater temperatures estimated from the abalone collected in 2012 reflected the in situ measured temperatures, but the reconstr…

S-34 and N-15 labelling to model S and N flux in plants and determine the different components of N and S use efficiency

2013

International audience; In order to highlight our understanding on ecosystems functioning and resource sharing/competition, either in artificial environment or agrosystems, according to changes in the climatic conditions, it is necessary to measure accurately element fluxes within plants. Stable isotopes allow tracking safely and accurately on a short time frame the behavior of elements in plants. After a short review devoted to isotopic studies of elemental flux within plants, we explain how a direct multiple labelling study might be conducted in a plant, so as to measure over short time nitrogen and sulfur acquisition, and assimilates arising from a labelled source.

A high-quality genome assembly from short and long reads for the non-biting midge Chironomus riparius (Diptera)

2020

AbstractBackgroundChironomus riparius is of great importance as a study species in various fields like ecotoxicology, molecular genetics, developmental biology and ecology. However, only a fragmented draft genome exists to date, hindering the recent rush of population genomic studies in this species.FindingsMaking use of 50 NGS datasets, we present a hybrid genome assembly from short and long sequence reads that make C. riparius’ genome one of the most contiguous Dipteran genomes published, the first complete mitochondrial genome of the species and the respective recombination rate as one of the first insect recombination rates at all.ConclusionsThe genome and associated resources will be h…