Search results for "POPULATION"
showing 10 items of 9945 documents
Trade and stowaways: molecular evidence for human-mediated translocation of eastern skinks into the western Mediterranean
2020
Human movements in the regions surrounding the Mediterranean Sea have caused a great impact in the composition of terrestrial fauna due to the introductions of several allochthonous species, intentionally or not. Reptiles are one of the groups where this anthropic impact is most evident, owing to the extensive intra-Mediterranean dispersals of recent chronologies. Chalcides ocellatus is a widespread skink with a natural distribution that covers almost the entire Mediterranean Basin. Two hypotheses have been proposed to explain its origin: natural dispersions and human translocations. Previous molecular data suggest the occurrence of a recent dispersal phenomenon across the Mediterranean Sea…
Assessing global range expansion in a cryptic species complex: insights from the red seaweed genus Asparagopsis (Florideophyceae)
2017
The mitochondrial genetic diversity, distribution and invasive potential of multiple cryptic operational taxonomic units (OTUs) of the red invasive seaweed Asparagopsis were assessed by studying introduced Mediterranean and Hawaiian populations. Invasive behavior of each Asparagopsis OTU was inferred from phylogeographic reconstructions, past historical demographic dynamics, recent range expansion assessments and future distributional predictions obtained from demographic models. Genealogical networks resolved Asparagopsis gametophytes and tetrasporophytes into four A. taxiformis and one A. armata cryptic OTUs. Falkenbergia isolates of A. taxiformis L3 were recovered for the first time in t…
<strong><em>Grandidierella</em> <em>bonnieroides</em> Stephensen, 1948 (Amphipoda, Aoridae)—first record of an establis…
2016
The first record in the Mediterranean Sea of the invasive aorid amphipod crustacean Grandidierella bonnieroides is presented. A widespread circumtropical species, recorded off the Saudi coast of the Arabian Gulf, the Red Sea and the Suez Canal, it may have been introduced into the Mediterranean through the Suez Canal. This tube-builder species of soft bottoms recently established a population in the polluted Haifa Bay, Israel. Further, this is the first Mediterranean record of the genus.
First assessment of the rose shrimp, Parapenaeus longirostris (Lucas, 1846) in the central Mediterranean
1995
Abstract Between June 1989 and May 1990 a 1 year programme based on commercial samples and statistics was carried out to assess Parapenaeus longirostris in the Sicilian Channel (Central Mediterranean), since most trawl-fishing occurs outside the area currently covered by trawl surveys of the National Research Council Institute based in Mazara del Vallo. Fishing takes place on three distinct grounds, where three different sub-stocks belonging to the same population could be identified based on length and maturity data. Length-based methods allowed calculation of all parameters needed to fit Beverton and Holt's (1957) and Thompson and Bell's (1934) models, while natural mortality could be est…
Community size affects the signals of ecological drift and niche selection on biodiversity
2019
AbstractEcological drift can override the effects of deterministic niche selection on small populations and drive the assembly of small communities. We tested the hypothesis that smaller local communities are more dissimilar among each other because of ecological drift than larger communities, which are mainly structured by niche selection. We used a unique, comprehensive dataset on insect communities sampled identically in a total of 200 streams in climatically different regions (Brazil and Finland) that differ in community size by fivefold. Null models allowed us to estimate the magnitude to which beta diversity deviates from the expectation under a random assembly process while taking di…
Density, social information, and space use in the common lizard (Lacerta vivipara)
2007
6 pages; International audience; Socially acquired information is widespread in the animal kingdom. Many individuals make behavioral decisions based on such social information. In particular, individuals may decide to leave or select their habitat based on social information. Few studies have investigated the role of density-related information, a potential social cue about habitat quality in dispersal. Here, we tested for the possibility that the phenotype of intruder common lizards (Lacerta vivipara) may inadvertently carry information about their natal population density. We found that such information use is likely. The behavior of focal lizard was influenced by the natal population den…
Levels of genetic differentiation and gene flow between four populations of the Scaly-naped Pigeon, Patagioenas squamosa : implications for conservat…
2021
Island-endemic columbid species are particularly vulnerable to environmental degradation, extreme climatic events, and interactions with exotic species. The situation might be even more critical in the case of exploited species, where legal hunting and poaching can severely affect population dynamics. Here we document for the first time the genetic structure of the Scaly-naped Pigeon, Patagioenas squamosa, a Caribbean-endemic columbid species of cynegetic interest, over a large part of its range. Using both mitochondrial DNA and nuclear markers (microsatellites), we investigated gene flow, genetic diversity, and genetic structure among four islands populations originating from Puerto-Rico, …
When less means more: evolutionary and developmental hypotheses in rodent molars.
2012
10 pages; International audience; Tooth number in rodents is an example of reduction in evolution. All rodents have a toothless diastema lacking canine and most premolars present in most other mammals. Whereas some rodent lineages retained one premolar (p4), many others lost it during evolution. Recently, an 'inhibitory cascade' developmental model (IC) has been used to predict how the first molar (m1) influences the number and relative sizes of the following distal molars (m2 and m3). The model does not, however, consider the presence of premolars, and here we examine whether the premolar could influence and constrain molar proportions during development and evolution. By investigating a l…
Evolution of mammal tooth patterns: new insights from a developmental prediction model.
2009
14 pages.; International audience; The study of mammalian evolution is often based on insights into the evolution of teeth. Developmental studies may attempt to address the mechanisms that guide evolutionary changes. One example is the new developmental model proposed by Kavanagh et al. (2007), which provides a high-level testable model to predict mammalian tooth evolution. It is constructed on an inhibitory cascade model based on a dynamic balance of activators and inhibitors, regulating differences in molar size along the lower dental row. Nevertheless, molar sizes in some mammals differ from this inhibitory cascade model, in particular in voles. The aim of this study is to point out arvi…
Dynamical model identification of population of oysters for water quality monitoring
2014
International audience; The measurements of valve activity in a population of bivalves under natural environmental conditions (16 oysters in the Bay of Arcachon, France) are used for a physiological model identification. A nonlinear auto-regressive exogenous (NARX) model is designed and tested. The model takes into account the influence of environmental conditions using measurements of the sunlight intensity, the moonlight and tide levels. A possible influence of the internal circadian/circatidal clocks is also analyzed. Through this application, it is demonstrated that the developed dynamical model can be used for estimation of the normal physiological rhythms of permanently immersed oyste…