The article reports on the first detailed vertebral and rib morphology of anguine taxon Pseudopus apodus using micro-computed tomography. A comparison shows significant morphological differences of vertebrae of Pseudopus relative to those of Anguis and Ophisaurus. Usually, there are 55 presacral vertebrae, two sacral, and 95-97 caudal vertebrae. Pseudopus apodus can be defined by 23 diagnostic features concerning the vertebral column. Although zygapophyseal articulation between atlas and axis is well developed in limbed anguid gerrhonotine lizards like Abronia or Barisia, it is absent in the extant representatives of the clade Anguinae, which are limbless. Thus, our study brings further support to the hypothesis about the complete reduction of this articulation in forms with reduced or absent limbs. Comparison of adult and juvenile morphology of vertebrae of P. apodus was also analyzed. Heterochrony in the evolution of this taxon was previously confirmed by its skull morphology and it can be also documented on the basis of vertebrae. Our data suggest that a peramorphic heterochronic process played a role in the evolution of this largest extant anguine species. Geometric morphometric analyses revealed a pattern of high vertebral disparity among species. We found a clear separation of limbless forms in morphospace. Pseudopus apodus always clusters within Ophisaurus-species confirming molecular and some morphological phylogenies. Only the first tail vertebra shows a distinct difference to those of Jana Ciceková is currently affiliated with The Bridge Language Centre, Baštová 344/7, 811 03 Bratislava 1.
Our study examines community structure and nymphal biology (life cycles and secondary production) of stoneflies in two adjacent mountain streams with different degree of forest cover in the Prosiečanka River Basin (Chočské Vrchy Mts., West Carpathians)
been identified as a major large-scale factor affecting stonefly community composition in streams [4], whereas important medium-and small-scale factors can include stream size, substratum and water quality.A windstorm in November 2004 flattened 12,000 hectares of forest along southerly oriented slopes of the Tatra Mountains, and also sections of brook catchment areas. Since this windstorm caused large scale destruction of mature forests over such an extensive area, including that of the riverine landscape of the brooks, this unique natural disturbance provided a great opportunity for ecological research [5,6].The Plecoptera are one of the best bioindicators of human disturbances in streams [7]. Within the benthic macroinvertebrates, stoneflies are selected for evaluation of long-term changes [8]. Stoneflies are useful biological indicators of river quality, reflecting stream degradation, land use, and deforestation [9,10].Ambühl [11] and Egglishaw [12] relate the distribution of several macroinvertebrate species to current water velocity and substrata. Egglishaw [12] showed that, even in what was apparently a fairly uniform stretch of riffle, i.e. a length of short shallow coarse-bedded stream, the densities of several benthic species varied greatly by site and were correlated with the substrata type. The riverbed gave ground for the interactive linkages between the fluvial-morphological, hydrological-hydraulic and sedimentation processes in space (lateral, longitudinal and vertical dimensions) and in time [13,14]. The result is a dynamic structure of morphological units (microhabitats), which form the basis of the structure and organization of biotic associations. The effects of flow on organisms can be expressed by the complex variable, shear stress [15]. Also, a correlation between average current velocity and hydraulic conditions near the substrate has been described [16], which indicates that average velocity has a significant relationship to conditions on the substratum and biota. Substrate heterogeneity is created by disturbance and variability in physical conditions [17]. Heterogeneity produces patchiness in environmental conditions [18], including food availability, which in turn results in high species diversity in benthic invertebrates.Abstract: Stonefly samples were collected from disturbed and undisturbed tributaries of the Tatra Mountains streams (the West Carpathians). In the autumn, at stable low discharge, the total density of stoneflies was significantly higher in the undisturbed streams. Microhabitats such as macrolithal (boulders), mesolithal (stones) and moss had higher stonefly density. Taxa of different species or genera have different demands for microhabitats. Very narrow spatial niches were found for the genera Rhabdiopteryx, Protonemura and Perlodes. The spatial niche overlap was low between the genera Rhabdiopteryx and Brachyptera, but was high between species of the Protonemura and Leucra genera. The highest biodiversity of stoneflies was on coarser substrata (except boulders) and m...
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