Search results for "Axon"
showing 10 items of 2126 documents
Invasive Alien Species and Their Effects on Marine Animal Forests
2020
Nonindigenous species are increasingly transported around the world through multiple pathways by a diversity of vectors. Invasive species are a subset of those that are introduced into the receptor community, where they establish and increase their population to a size where they impact the native system. Marine invasive species can therefore interact with and modify native animal forests and/or create novel ones resulting in simple-to-complex changes in material cycling, energy flow, ecosystem structure, and function. Despite the ever increasing number of studies dealing with marine invasive species, mostly biological invasions are mentioned generically as one of a number of threats of dir…
On the identity of Ischyropsalis dentipalpis Canestrini, 1872 and description of Ischyropsalis lithoclasica sp. n. (Opiliones: Ischyropsalididae)
2010
Ischyropsalis dentipalpis Canestrini, 1872 is re-defined, and a neotype from the type locality in the Aosta Valley, Italy, is assigned. I. helvetica Roewer, 1916 (sensu Martens 1978) is shown to be conspecific and therefore is synonymised with I. dentipalpis. A population from Bergamo Province, Italy, formerly assigned to I. dentipalpis (sensu Martens 1978), is here regarded as a different species and described under the name Ischyropsalis lithoclasica sp. n. Discrimination of males is possible by genital characters and by the shape of the cheliceral and pedipalpal apophyses. Females are distinguished by peculiarities of cheliceral spination. The distribution of I. lithoclasica n. sp. is al…
Comparative analysis of biological and ecological differentiation of Anemone palmata L. (Ranunculaceae) in the western Mediterranean (France and Spai…
2002
The western Mediterranean geophyte Anemone palmata L. is one of the most endangered angiosperm taxa in France. The biological and ecological characteristics of French populations are contrasted with those of populations from near the centre of the species distribution in east Spain. A Correspondence Analysis discriminates the French and Spanish populations according to substrate and the composition of the plant communities where they grow. The karyological study reveals that east Spanish plants are autotetraploid, whilst the French are all diploid. In addition, morphological differences were registered, Spanish plants generally being more vigorous. French populations consist mostly of senil…
Differences in gene flow in a twofold secondary contact zone of pond turtles in southern Italy (Testudines: Emydidae:Emys orbicularis galloitalica,E.…
2015
Using virtually range-wide sampling for three pond turtle taxa (Emys orbicularis galloitalica, E. o. hellenica, E. trinacris), we analyse gene flow across their southern Italian contact zone. Based on population genetic analyses of 15 highly polymorphic microsatellite loci and a mitochondrial marker, we show that the general genetic pattern matches well with the current taxon delimitation. Yet, single individuals with conflicting genetic identity suggest translocation of turtles by humans. In addition, we identify in south-western France and the vicinity of Rome populations being heavily impacted by introduced turtles. Cline analyses reveal that the major genetic break between E. o. galloit…
Parvalbumin-containing neurons in the cerebral cortex of the lizardPodarcis hispanica: Morphology, ultrastructure, and coexistence with GABA, somatos…
1993
The morphology, fine structure, and degree of colocalization with GABA, somatostatin, and neuropeptide Y of parvalbumin-containing cells were studied with immunocytochemistry in the cerebral cortex of the lizard Podarcis hispanica. Parvalbumin-containing cells make up a morphologically heterogeneous population of spine-free neurons, displaying the morphological features of nonprincipal cells previously described in Golgi studies. Electron microscopically, parvalbumin-immunoreactive cell bodies are similar in all cortical areas and layers. The perisomatic input is moderate in number, and boutons with either round clear vesicles or flattened vesicles were observed making asymmetric or symmetr…
Brassica trichocarpa (Brassicaceae), a new species from Sicily
2013
A new species of Brassica from Sicily, namely B. trichocarpa, is described and illustrated. This suffrutex was found on a calcareous peak of a mount near Palermo, where it is represented by a single population occupying a really small surface. It is well differentiated from the other perennial species belonging to B. sect. Brassica mainly in having hairy ovary and very short, thickened, hairy, not torulose fruits. Its relationships and taxonomical position within this group are examined too. An analytical key of the current taxa belonging to the genus Brassica sect. Brassica is also provided.
Genetic differentiation of three species of Matthiola (Brassicaceae) in the Sicilian insular system
2005
We examined the genetic variation of 12 isozyme loci in 14 populations of Matthiola (Brassicaceae) representing the geographic distribution of the species M. incana, M. fruticulosa ssp. fruticulosa and M. tricuspidata in the Sicilian insular system and the adjacent mainland areas to estimate the levels and apportionment of genetic variation in the insular populations and to understand their population dynamics. The disparity in the distribution of polymorphism in populations of M. incana ssp. incana (low within populations but with high values of F ST and G ST ) contrasts with the homogeneity in the inter-population distribution of the high genetic variation detected in M. tricuspidata and …
Middle Cambrian Gogiid Echinoderms from Northeast Spain: Taxonomy, Palaeoecology, and Palaeogeographic Implications
2009
Gogia parsleyi Zamora sp. nov. and Gogia sp. are described from two different echinoderm assemblages, both from the middle Cambrian of the Murero Formation (Iberian Chains, NE Spain). Gogia parsleyi is reconstructed and described on the basis of fifteen complete or partial specimens and numerous isolated plates. It is characterised by spiralled brachioles, simple epispires, sometimes covered by stereomic domes or tiny cover plates, and by thecal plates arranged in subregular circlets. This gogiid population comprises juveniles, advanced juveniles and mature individuals. The material was found in the upper part of the Murero Formation (upper Caesaraugustian—lower Languedocian). Gogia sp. is …
Genetic and morphological differentiation ofDikerogammarusinvaders and their invasion history in Central Europe
2002
SUMMARY 1. Biological invasions often involve close taxonomic relatives either as native/invader pairs or as invader/invader pairs. Precise identification and differentiation of species is therefore of paramount importance to reconstruct the invasion history. Genetic studies are indispensable in the case of morphologically conservative taxonomic groups. 2. We analysed the Pontocaspian freshwater amphipods Dikerogammarus that have successfully invaded the benthos of large Central European rivers. Taxonomic uncertainties were clarified by phylogenetic analyses of mitochondrial 16S and COI genes. The three-way partitioning of allozyme genotypes in a syntopic population further corroborated the…
Parasitic infracommunities of the Aegean wall lizard Podarcis erhardii (Lacertidae, Sauria): isolation and impoverishment in small island populations
2009
AbstractThe Aegean wall lizard Podarcis erhardii, is widely distributed across the islands of the Aegean Sea (Greece). While there exists a relatively substantial body of knowledge on the ecology and life history of the species, the parasite communities of the taxon remain almost completely unknown. Quantifying the composition of these communities in P. erhardii is not only important for autoecological reasons, but also because inter-island comparisons of this lizard's parasite communities can shed light on the factors that structure parasite diversity in general. Here we investigate the gastrointestinal parasite communities of P. erhardii populations occurring on 16 landbridge islands of t…