Fine structure of the ependymal cells in the area postrema of the domestic fowl

Summary The ultrastructure of the ependymal cells in the area postrema of the domestic fowl was studied by scanning and transmission electron microscopy. The ependymal surface of the area postrema is covered with many furrows and ridges. These ridges consist of ependymal cells aggregated in a fan-like shape. The ependymal cell lacks clustered cilia, microvilli are few, and a long basal process extends through the parenchymal layer of the area postrema. Within the cytoplasm as well as in the basal process, a spherical body with a diameter ranging from 1.5 to 2 gmm is occasionally observed.This work was supported by a Scientific Research Grant, No. 144017, from the Ministry of Education of Japan to Professor M. YasudaThe authors are grateful to Drs. T. Fujioka and T. Watanabe for their valuable advice     

A Novel Method to Analyze the Similarity of Biological Sequences

Abstract

In this paper, we propose a new method based on the 2-D graphical representation to analyze the similarity of biological sequences and classify the protein secondary structure sequences. Instead of computing some characteristics from the distance matrix, the average area surrounded by the curve and X axis is computed as a new invariant. The new method is tested on two sets: the coding sequences of 30 mitochondrial genes from NCBI and 12 protein secondary structure sequences. The similarity/disimilarity and phylogenetic tree (dendrogram) of these sequences verify the validity of our method.     

Interpreting ecological patterns in an intact estuary, South-west New Zealand World Heritage Area

Vegetation pattern, soil attributes, and salinity regimes along with several other environmental factors were studied in a small (11 ha) but unmodified estuary in south Westland, New Zealand. Part of an unmodified 40 km² catchment within the South-west New Zealand World Heritage Area, the Hapuka Estuary, formed behind a 5-km long barrier beach, provides considerable ecological value as well as baseline, conservation advocacy and educative potentials both in a national and international context. Seventy-four quadrats were sampled randomly along five transects at right angles to the main Hapuka River. Eight plant communities comprising 141 native and thirteen exotic vascular species, were differentiated using multivariate analyses, from bare mud (mean elevation 1.23±0.24 m above Mean Low Water Spring (MLWS)), saltmarsh and shrubland associations through to the adjacent podocarp-broadleaved rain forest (4.53±0.74 m above MLWS). Bulk density of the upper 10 cm of substrate varied from a maximum of 1.15 g cm^?3 in the lowest elevation association to a minimum of 0.15 g cm^?3 in the rain forest. pH showed a similar trend with values of 6.97 and 4.31, respectively. The reverse pattern was evident with organic matter, with the highest content (53% ODWt) in the rain forest substrate. The water which irrigates the saltmarsh at high tide reaches 15–19» salinity on calm days but may be much less saline when moderate to strong southerly winds counter the tidal influence. Northerly winds, or a southern outlet through the barrier beach, intermittently evident in the past, are likely to enhance salinity of the tidal waters across the saltmarsh. Ordination of the vegetation samples indicated a very strong gradient associated with Axis 1 (eigenvalue=0.872) and Axis 2 (eigenvalue=0.461). Vector fitting of nine measured environmental factors indicated a strong positive correlation with Axis 1 of the ordination, of soil pH, sodium and conductivity, and negative correlations with elevation, soil water, organic matter and potassium contents.     

Designing nature reserves: traditional criteria may act as misleading indicators of quality

Traditionally, numerous criteria have been used for selecting valuable areas for the establishment of nature reserves. In most cases these criteria are applied indiscriminately with the assumption that their generalized use gives them universal validity. In this study we test the value of different variables (area and shape of patches of natural vegetation, degree of internal fragmentation, and diversity of habitats at the periphery of patches) at the landscape level as indicators of plant richness and diversity, and relative abundance of native plants, in a group of natural vegetation relicts ranging from 0.004 km² to 1.027 km² and surrounded by sub-urban and industrial settings. Species richness, diversity, and number of native and exotic species increased with the area of the patches. The shape of the patch was the second most important variable to influence species richness and diversity. The number of exotic species increased with increasing numbers of native plants. Thus, patch size and plant richness should be carefully used for selecting conservation areas because it could result in choosing places threatened by the presence of exotics. Many of the other variables analysed showed no effects on biodiversity at the temporal and geographic scales considered. Ignoring these outcomes could result in choosing sub-optimal areas. We recommend the critical use of general criteria considering the selection process as an opportunity to evaluate the relevance of each criterion at the local level.     

Survival and habitat use in translocated and resident greater prairie-chickens

Translocation, or the purposeful movement of organisms from one location to another for conservation, is currently being used to bolster populations of the endangered greater prairie-chicken (Tympanuchus cupido). We used radiotelemetry to compare survival between 58 resident birds and 54 newly translocated greater prairie-chickens that were sourced from a location more than 325 km away. Model averaged survival estimates were lower in translocated birds (0.42; 95% CI: 0.17–0.66) than in resident prairie-chickens (0.65; 95% CI: 0.46–0.79) through the breeding season. Habitat, sex and year were each included in at least 1 of the top 4 models, but the model averaged confidence intervals for each parameter encompassed zero. Survival of both resident and translocated prairie-chickens increased throughout the breeding season. Both translocated and resident prairie-chickens selected for core prairie habitat over agriculture, and birds tended to avoid surrounding private grasslands and wooded areas. We suggest that future translocation projects account for reduced survival of translocated birds when determining the appropriate release cohort sizes and sex ratios. We also recommend that future management for greater prairie-chicken habitat focus on the expansion of core protected patches of prairie to promote elevated survival and better chances of conservation success.     

Misconceptions about parsimony analysis of endemicity

Parsimony analysis of endemicity (PAE) has been widely criticized in the recent literature based on methodology rather than on theory. Here I argue that most of the criticisms of PAE result from confusion between the dynamic and static approaches of PAE, by both users and critics of the method. Originally, PAE (the dynamic approach) was proposed primarily for historical comparisons of biotic distributions based on geological and stratigraphical information; that is, the stratigraphical record of the biota within two or more horizons was used to evaluate changes (layer by layer) in their distributional patterns. This led to an analysis of the biota throughout space and through time. On the other hand, the static approach excluded the temporal component and based the analysis on a single geological horizon. Most problems exemplified and discussed in the literature refer to the static approach. In addition to this defence of the original PAE, I present some new criticisms regarding the application of PAE using artificially delimited areas (for example areas defined by geopolitical boundaries), which may lead to incorrect interpretations. Recently, several variations of static PAE have appeared: some designed to accommodate ecological data (e.g. parsimony analysis of distributions – PAD); others that incorporate phylogenetic content (e.g. cladistic analysis of distributions and endemism – CADE); and some that have been integrated with other historical methods (e.g. panbiogeography) in order to detect and evaluate hypotheses of biogeographical homologies. Biogeographers, both ecological and historical, should be aware of the problems and limitations of both dynamic and static PAE and evaluate new variations of PAE (PAD, CADE, etc.). Finally, I argue in favour of an independent and pluralist discipline of biogeography that treats biogeography as related to systematics but not dependent on it, as some scholars have assumed.