Regional Variation In Size Research Articles

Morphology, geographical variation and the subspecies of Marsh Tit Poecile palustris in Britain and central Europe

Capsule All British Marsh Tits belong to subspecies Poecile palustris dresseri, being smaller than nominate P. p. palustris of central Europe.Aims Determining the subspecies of Marsh Tit in Britain to test whether ssp. P. p. palustris occurs in northern England and Scotland, by assessing regional variation in size compared with central European birds.Methods 1147 wing length and 250 tail length measurements from 953 Marsh Tits were compared between eight British locations to test for regional variation. Biometrics were compared between birds from Britain and six locations within the continental European range of ssp. palustris.Results There was no regional variation in wing or tail lengths among British Marsh Tits, indicating that all resident birds belong to ssp. dresseri. There was no evidence supporting the existence of ssp. palustris in northern England. British birds were significantly smaller than those from continental Europe, with proportionately shorter tails, consistent across all age and sex classes.Conclusion All British Marsh Tits should be considered as ssp. dresseri, with ssp. palustris being limited to continental Europe. With no evidence of regional variation in size within Britain, reliable sexing methods based on biometrics could be applied in demographic studies throughout the country.

Sonographic evaluation of the spleen among sickle cell disease patients in a teaching hospital in Nigeria.

Regional variations in size and parenchyma echo-texture of the spleen among sickle cell disease (SCD) patients have been documented in various publications. The objectives of this study were to assess the size and parenchyma echo-texture of the spleen of SCD patients and ascertain the relationship of age, height and weight with the spleen sizes. This was a cross sectional study involving 103 each of SCD and age matched control subjects. Aloka ST- 550 -3500 ultrasound machine with 3.5 and 5 MHz convex transducers was used to scan the subjects over a 15 months period (September, 2012 to November, 2013). The age, height and weight of each subject were recorded. The spleen sizes of SCD patients were generally larger than those of the controls (p < 0.05). Abnormal spleen parenchyma of varied appearances was found among the SCD subjects. There were negative correlations between mean spleen sizes and height, weight and age in SCD patients but positive correlations were found between them in the controls. Routine sonographic assessment of spleen size and echo-texture is useful in the management of SCD patients.

EarlyHomo

The origin of Homo is argued to entail niche differentiation resulting from increasing terrestriality and dietary breadth relative to the better known species of Australopithecus (A. afarensis, A. anamensis, A. africanus). I review the fossil evidence from ∼2.5 to 1.5 Ma in light of new finds and analyses that challenge previous inferences. Minimally, three cranial morphs of early Homo (including Homo erectus) exist in eastern Africa (1.9–1.4 Ma), with at least two in southern Africa. Because of taphonomic damage to the type specimen of Homo habilis, in East Africa two species with different masticatory adaptations are better identified by their main specimen (i.e., the 1813 group and the 1470 group) rather than a species name. Until recently, the 1470 group comprised a single specimen. South African early Homo are likely distinct from these groups. Together, contemporary early H. erectus and early Homo are bigger than Australopithecus (∼30%). Early H. erectus (including recently discovered small specimens) is larger than non-erectusHomo (∼15%–25%), but their size ranges overlap. All early Homo are likely to exhibit substantial sexual dimorphism. Early H. erectus is less “modern” and its regional variation in size more substantial than previously allowed. These findings form the baseline for understanding the origin of the genus.

Regional variation in maturation of sandeels in the North Sea

Abstract Boulcott, P., Wright, P. J., Gibb, F. M., Jensen, H., and Gibb, I. M. 2007. Regional variation in maturation of sandeels in the North Sea. – ICES Journal of Marine Science, 64: 369–376. The current assessment of lesser sandeel (Ammodytes marinus) in the North Sea assumes a single stock and a knife-edge maturity ogive. However, there is evidence that the North Sea stock consists of several reproductively isolated components, raising the possibility of demographic differences among regional aggregations. We examine regional variation in size- and age-at-maturity in four components of the North Sea stock. Surveys in 1999 indicated pronounced regional differences in length- and weight-at-age, implying a disparity in growth rate across the North Sea. Logistic regression revealed that the onset of maturity was significantly related to regional distribution, in addition to length and age, with a tendency for fish off the UK's northeast coast to mature later and smaller than elsewhere. No significant effect of year on either growth or length-at-maturity was revealed from a comparison with other data collected in 2004. The results show that important regional phenotypic variation not currently represented in stock assessments could have implications for the local sustainability of sandeel aggregations.

Variation in size and shape of Sphagnum hummocks in relation to climatic conditions in Hokkaido Island, northern Japan

Regional variation in size and shape of Sphagnum hummocks of eight lowland mires throughout Hokkaido Island, northern Japan, was examined in relation to climatic factors. The size and shape of hummocks significantly differed among the regions: low and flat hummocks occurred in the northern region and next to the Sea of Japan; moderately raised and conical hummocks occurred in the western part of the Pacific coast; and extremely raised and cylindrical hummocks occurred in the eastern region. Multiple regression analysis revealed that the mean and maximum heights and height/basal area of hummocks were negatively correlated with evapotranspiration rate (E0) in summer, duration of sunshine, and air temperature. Of these, evapotranspiration rate in summer positively correlated with radiation and thermal factors. Mean height of hummocks within a mire was increased with precipitation during the growing season. Because the regional difference of the hummock form was not related to the difference in nutrient conditions, the effects of evapotranspiration and precipitation prevailed over edaphic conditions. Higher E0 in summer was considered to cause water stress for hummock species in the northern region and next to the Sea of Japan, whereas heavy rainfall relieved it in the western region of the Pacific coast. Consequently, lower and flat hummocks were a result of the higher E0 in summer, moderately raised and conical hummocks of the medium E0 and high precipitation, and extremely raised and cylindrical hummocks of a lower E0 due to prolonged foggy days.Key words: evapotranspiration, duration of sunshine, minerotrophy, ombrotrophy, precipitation.

Neural tube formation in the mouse: a morphometric and computerized three-dimensional reconstruction study of the relationship between apical constriction of neuroepithelial cells and the shape of the neuroepithelium

Morphometry and computerized three-dimensional reconstruction were used to study the relationship between apical constriction of neuroepithelial cells and the pattern of bending of the neuroepithelium in the developing neural tube of the 12-somite mouse embryo. The neuroepithelium of the mouse exhibits prominent regional variations in size and shape along the embryo axis. The complex shape of most of the cephalic neural tube (e.g., forebrain and midbrain) is due to the coexistence of concave and convex bending sites whereas more caudal regions (e.g., hindbrain and spinal cord) generally lack sites of convex bending and have a relatively simple shape. The apical morphology of neuroepithelial cells was found to be correlated more closely with the local status of bending of the neuroepithelium than with the specific region of the neural tube in which they are located. In areas of enhanced apical constriction, microfilament bundles were particularly prominent. Morphometry revealed that patterns of bending of the neuroepithelium were correlated almost exactly with those of apical constriction throughout the forming neural tube. These findings support the idea that apical constriction of neuroepithelial cells, resulting from tension generated by microfilament bundles, plays a major role in bending of the neuroepithelium during neural tube formation in the mouse.

Filiform papillae of cat tongue.

A pronounced species variation in the organization of filiform papillae has been observed. Preliminary histologic studies of cat tongue revealed marked regional variations in size, shape and organization of filiform papillae. Therefore, a correlated light microscopic, transmission and scanning electron microscopic study of tissue samples of representative areas of the cat tongue was undertaken for further elucidation. Results showed that filiform papillae on the tip of the tongue were short and exhibited several conical processes from the base of each papilla. In contrast, filiform papillae in the midportion of the dorsum of the tongue consisted of a large mound with a single sharp spinous process projecting posteriorly. In the region of the vallate papillae, the filiform papillae were shorter and more conical than those on the midportion of the tongue. In addition, keratohyalin granules in filiform papillae were comprised of an eosinophil spheroid with small basophil attachments.