Effects of forest regeneration on the structure of bird communities in northern Finland

Breeding bird communities in five stages of secondary forest succession were studied in northeastern Finland in 1980–82. Three groups of communities were distinguished: open land, brush phase and forest communities, dominated by Motacilla alba and Oenanthe oenanthe, Phylloscopus trochilus and Anthus trivialis, Phylloscopus trochilus and Fringilla montifringilla , respectively.
Pair density, number of species, biomass of adult birds and species diversity increased in the course of succession, none of these, however, monotonously. Average bird weight showed a decreasing trend although the variation was considerable. The degree of specialization in communities (measured by ratios derived from numbers of species, genera and families) increased in the course of succession with the exception that the initial stage had relatively high values. Species nesting and feeding in trees and shrubs increased in numbers during forest regeneration whereas species nesting and feeding on the ground showed the opposite trend. The proportions of hole-nesting and sedentary species increased with increasing forest age.
The initial stages of forest succession in the north are occupied by specialized open habitat species breeding originally on open bogs and shores. These communities thus clearly differ from those predicted from the general theory of succession, which postulates that the pioneer stages of succession are dominated by habitat generalists and that these communities should have relatively low values of community diversity.     

Mass Spectrometric Analyses of Brain Synaptic Peptides Containing Taurine

The structure of a number of low-molecular-weight acidic peptides containing taurine prepared from calf brain synaptosomes and their subcellular vesicles was studied using electron impact mass spectrometry. At least seven sequences could be identified: N-acetylaspartyl-glutamyl-taurine, N-acetylaspartyl-taurine, N-acetylglutamyl-taurine, glutamyl-taurine, aspartyl-taurine, seryl-glutamyl-seryl-taurine, and seryl-taurine.     

Strain while skiing and hauling a sledge or carrying a backpack

Eight soldiers on skis transported three loads of different weights on the level, uphill and downhill. The load was placed either on a cargo sledge or in a backpack or divided between the sledge and the backpack. The sledge had a new type of haulage-shaft, which was fixed to both sides of the pelvis. A service belt spread the pull over the whole upper body. The physical stain of different transport methods and the serviceability of the sledge was studied by measuring heart rate (HR), oxygen consumption, ventilation, and perceived exertion. The results indicate that both absolute and relative strain were systematically lower when pulling the load on the sledge than when carrying it in the backpack and on the sledge. HR when pulling a load equal to the human body weight on the sledge was on average 133 beats X min-1; HR was significantly higher 144 beats X min-1 when the load was divided between backpack and sledge. At the lower load level the differences between the transport methods were not significant for HR, oxygen consumption or ventilation. Uphill travel increased oxygen consumption by about 50% over that on the level. Perceived exertion at all load levels was significantly lower with the sledge than with the backpack alone or in combination. The estimated maximal allowable working time emphasized the advantage of the sledge and the importance of high physical working capacity. The maneuverability of the sledge with the new haulage shaft was good and the braking mechanisms worked well.(ABSTRACT TRUNCATED AT 250 WORDS)     

Geographical variation in circadian eclosion rhythm and photoperiodic adult diapause inDrosophila littoralis

Summary The time measuring system ofDrosophila littoralis strains originating between 40–70° N was found to be highly variable and latitude dependent. The critical daylength for photoperiodic adult diapause varied from 12 h or no diapause response in the south to 20 h in north. The median timing of pupal eclosion rhythm varied correspondingly from 21 h to 12 h from lights off in LD 321, and the period of free-running rhythm of eclosion from 24 h to 19 h. The phase of the free-running rhythm was also variable, and correlated with the phase of the entrained rhythm. Latitudinal variation in the entrained rhythm of eclosion and in diapause is adaptive, leading to eclosion early in the morning and to overwintering at the adult stage. In some strains with a late phase of eclosion, strong transient cycles were seen following the transition from LL to DD. A total damping of the free-running eclosion rhythm within 2–7 days was common to all strains. This damping was more pronounced in the northern strains. The phase and period of eclosion rhythms were statistically independent. Diapause was not correlated with any parameters of the eclosion rhythm in the analysis. Diapause may still be influenced by the period of the eclosion rhythm, even though its minor contribution may be masked by a more variable, eclosion rhythm independent system in the determination of diapause.Abbreviations, symbols and terms LD Light/dark; as in LD 321 meaning a cycle of 3 h light21 h darkness - LL Continuous light - DD Continuous darkness - T Period of a Zeitgeber cycle - Natural period of eclosion rhythm in constant conditions - _EL Phase of the free-running rhythm of eclosion - A Amplitude of the free-running rhythm of eclosion; possible range is from 4.17% (no rhythmicity) to 20% (the daily eclosion peaks 2–6 within 5 h each) - P Persistence of the free-running rhythm of eclosion; the number of daily eclosion peaks where the mean for five highest hourly percentages still exceed 6% - A phase shift, expressed in h; a re-setting of a rhythm; either as an advance shift (i.e. earlier= +), or as a delay shift (i.e. later = –) - PRC Phase-response curve - _LD Phase of entrained rhythm of eclosion; e.g. _{LD 321} is the median hour of eclosion peak from lights off at LD 321 - SD _ecl Amplitude of the entrained rhythm of eclosion; the smaller SD_ecl the higher the amplitude - PPRC Photoperiodic response curve; proportion of females in diapause displayed as a function of daylength - CDL Critical photoperiod; the photoperiod in the 24 h LD cycle at which 50% of the population studied diapauses - SD _diap Accuracy of diapause response of a strain; the smaller the SD_diap the more accurate the response - Cdl The main locus controlling CDL inD. littoralis     

Lymphoid cell subclasses in rejecting renal allograft in the rat

We have quantitated the frequency of lymphoid cell subsets in rejecting renal allografts and in the spleen of the allograft recipient during drug-unmodified rejection in the rat. The number of inflammatory (white) cells in the graft was approximately similar to the number of white cells responding to the allograft in the recipient spleen. The inflammatory population of the graft consisted of lymphoid cells and mononuclear phagocytes, with increasing numbers of macrophages toward the end of rejection. Analysis of allograft cellular dispersates with monoclonal antibodies directed to the lymphoid cell subsets demonstrated that although the majority of allograft-infiltrating lymphocytes were T cells, a sizable B-cell proliferation and immunoglobulin synthesis was associated with the inflammatory response of rejection. Within the T-cell subset, the T suppressor/killer cells predominated in the graft whereas the predominant lymphoid cell subset responding to the allograft in the recipient spleen was the T helper cell.     

Sequential Expression of Nucleoproteins during Rat Spermiogenesis

Transition proteins and protamines are highly basic sperm-specific nuclear proteins that serve to compact the DNA during late spermiogenesis. To understand their sequential role in this function, transition protein 1 (TP1), transition protein 2 (TP2), and protamine 1 (P1) were assayed by polyacrylamide gel electrophoresis in pools of microdissected, staged seminiferous tubule segments in the rat. The results were compared with immunocytochemical analyses of squash preparations from accurately identified stages of the epithelial cycle. TP2 was the first to appear as a faint band at stages IX–XI, followed by high levels at stages XII–XIV of the cycle. TP1 showed a low expression at stage XII of the cycle and peaked at stages XIII–I, whereas protamine 1 first appeared at stage I of the cycle and remained high throughout the rest of spermiogenesis. Immunocytochemical analyses and Western blots largely confirmed these results: TP2 in steps 9–14, TP1 in steps 12–15, and P1 from late step 11 to step 19 of spermiogenesis. We propose that TP2 is the first nucleoprotein that replaces histones from the spermatid nucleus, and its appearance is associated with the onset of nuclear elongation. TP1 shows up along with the compaction of the chromatin. The two transition proteins seem to have distinct roles during transformation of the nuclei and compaction of spermatid DNA.     

Species richness in mammalian herbivores: patterns in the boreal zone

Latitudinal gradients in species diversity are well established for a number of plant and animal taxa. Both historical and present-day environmental factors have been suggested to be responsible for observed patterns. We tested the hypothesis that current environmental features of the environment (primary productivity and regional landscape structure) may explain the longitudinal variation in species richness of mammalian herbivores in the Holarctic boreal zone. Mammalian herbivore species diversity was strongly correlated with a number of environmental variables measured. We reduced the data set by a principal components analysis (PCA), and found that in the Palearctic, species richness is positively related to warm climate (high temperature sum), the number of hardwood species, and the area of boreal forest. In the Nearctic, species richness increases as the length of the growing season and the number of coniferous tree species increase. Thus indirect measures of primary productivity as well as tree species number may accurately predict species richness in mammalian herbivores. In addition, there seems to be a strong species-area effect at the regional level. The larger and more homogeneous in terms of forest coverage a boreal section is, the more species coexist there.     

Conservative resource utilization in the common blue butterfly–evidence for low costs of accepting absent host plants?

We studied host plant preference of the common blue butterfly, Polyommatus icarus , and larval performance on two different host plants, Oxytropis campestris and Lotus corniculatus . The study species is a small lycaenid butterfly believed to be relatively sedentary. The study populations originated from two different and widely separated geographical areas. In one area both hosts are naturally occurring, with O. campestris being most abundant at the study sites, in the other area only one of the host plants, L. corniculatus , is present. There was no difference in oviposition preference or larval performance between populations from the two different areas. Hence, P. icarus from sites dominated by O. campestris has not evolved a higher preference for or better performance on this host plant. More surprisingly, P. icarus from the area were O. campestris is completely absent has retained not only good larval performance on this host plant but also high female preference for it. This conservatism at a large geographical scale is seen even though there seems to be genetic variation present in both populations, at least for preference but perhaps also for performance. We suggest that such lack of variation in resource utilization between populations may be evidence for weak selection against "preferences" for plants that are rare or absent. A combination of other constraining factors may also contribute to some degree, especially stepping-stone gene flow between populations.