Kokko, H., Pöysä, H., Lindström, J. & Ranta, E. 1998: Assessing the impact of spring hunting on waterfowl populations. — Ann. Zool. Fennici 35: 195–204.
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Hissa, R., Puukka, M., Hohtola, E., Sassi, M.-L. & Risteli, J. 1998: Seasonal changes in plasma nitrogenous compounds of the European brown bear (Ursus arctos arctos). — Ann. Zool. Fennici 35: 205–213.
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Hissa, R., Hohtola, E., Tuomala-Saramäki, T., Laine, T. & Kallio, H. 1998: Seasonal changes in fatty acids and leptin contents in the plasma of the European brown bear (Ursus arctos arctos). — Ann. Zool. Fennici 35: 215–224.
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Tierno de Figueroa, J. M., Luzón-Ortega, J. M. & Sánchez-Ortega, A. 1998: Imaginal biology of the stonefly Hemimelaena flaviventris (Pictet, 1841) (Plecoptera: Perlodidae). — Ann. Zool. Fennici 35: 225–230.
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Davies, M. S. & Hatcher, A. M. 1998: The energy budget: a useful tool? — Ann. Zool. Fennici 35: 231–240.
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Danielsson, I. 1998: Mechanisms of sperm competition in insects. — Ann. Zool. Fennici 35: 241–257.
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Kokko, H., Pöysä, H., Lindström, J. & Ranta, E. 1998: Assessing the impact of spring hunting on waterfowl populations. — Ann. Zool. Fennici 35(4): 195–204.
Harvesting prior to the breeding season is widely considered ‘unwise’ since it has the bearing of deducting from the capital. However, spring hunting is still a common practice in many parts of the world, and its true effects remain uninvestigated. We present a model to investigate the range of possible effects of spring harvesting on waterfowl populations. The cost of spring harvesting is defined as corresponding loss in harvest opportunities in autumn; this cost may be sex-specific. Factors increasing the cost are monogamy, high breeding output, high summer survival and weak density dependence in summer, such that the population is mainly regulated through winter conditions. If the relative success of unpaired individuals is high (as in polygynous species if males are abundantly available after spring hunting), the cost of killing females may increase while that of killing males is reduced. Spring sex ratios may be more important in determining the cost than whether hunting occurs before or after pairing. Killing males can have surprisingly high costs and they may even exceed the cost of killing females if sex ratios are female-biased.
Hissa, R., Puukka, M., Hohtola, E., Sassi, M.-L. & Risteli, J. 1998: Seasonal changes in plasma nitrogenous compounds of the European brown bear (Ursus arctos arctos). — Ann. Zool. Fennici 35: 205–213.
The object of this study was to obtain quantitative information about the seasonal changes in plasma amino acids and other nitrogen compounds of the captive European brown bears (Ursus arctos arctos) studied between May 1993 and May 1997. Altogether 56 blood samples were analyzed by ion-exchange chromatography. Analysis of plasma revealed that the urea concentration during the denning period was only half of that measured in summer, whereas ammonia and [alpha]-amino-butyrate concentrations did not change. The concentrations of taurine and arginine were significantly (p < 0.001 and p ~ 0.003, respectively) lower, while ornithine significantly (p < 0.001) and citrulline somewhat higher in winter as compared with the other seasons. These changes indicate active urea recycling, and the synthesis of non-essential amino acids with ammonium and glycerol as precursors. Of essential amino acids, the levels of phenylalanine, lysine and methionine and of non-essential ones, alanine and histidine were significantly elevated during the denning period. No consistent changes occurred in other amino acids. One indication of the degradation of muscle protein as a source of amino acids in winter was the significant increase of 3-methylhistidine concentration in plasma. However, the degradation of type I collagen also increased, since the concentration of the cross-linked carboxyterminal telopeptide of type I collagen (ICTP) was about 3.5-fold higher in winter than in summer. These changes indicate that de novo synthesis of essential amino acids is not necessary in winter sleeping bears.
Hissa, R., Hohtola, E., Tuomala-Saramäki, T., Laine, T. & Kallio, H. 1998: Seasonal changes in fatty acids and leptin contents in the plasma of the European brown bear (Ursus arctos arctos). — Ann. Zool. Fennici 35: 215–224.
The goal of this study was to examine whether or not the preparation of the bear to winter sleep requires changes in the composition of plasma fatty acids similar to those observed in deep hibernators. Seasonal changes in plasma fatty acids of six captive European brown bears (Ursus arctos arctos) were investigated between 1991 and 1996. Altogether fifty plasma samples were analysed chromatographically. The weight percentage of unsaturated to saturated fatty acids was 37.1% in winter but only 32.3% in summer. The proportions of palmitic (16:0), octadec-11-enoic (18:1n-7), arachidonic (20:4n-6), and docosahexaenoic (22:6n-3) acids increased significantly in the total fatty acid pool in winter. At the same time, a significant decrease in concentrations of heptadecanoic (17:0), stearic (18:0), oleic (18:1n-9), [gamma]-linolenic (18:3n-6), [alpha]-linolenic (18:3n-3) and eicosapentaenoic (20:5n-3) acids was observed. Some fatty acids also act as precursors in the synthesis of specific tissue hormones. The leptin level reached its maximum just prior to winter sleep, i.e. when fat reserves were greatest.
Tierno de Figueroa, J. M., Luzón-Ortega, J. M. & Sánchez-Ortega, A. 1998: Imaginal biology of the stonefly Hemimelaena flaviventris (Pictet, 1841) (Plecoptera: Perlodidae). — Ann. Zool. Fennici 35: 225–230.
We studied various aspects of the imaginal biology of the stonefly Hemimelaena flaviventris in the southern Iberian Peninsula. This species was found to have a spring flight period (May and June). A great variety of components were recorded in its diet (e.g., pollen grains, especially of Pinus; cyanoficeas; cyanolichens; coarse particulate matter), indicating little dietary selectivity. We also analysed male drumming (three beats with intervals of 122.39 and 82.25 ms) as well as female drumming (1–3 beats, mean = 1.41; intervals between beats = 97.10 and 120 ms), suggesting a simple, monophasic model of intersexual vibration call. Mating duration ranged from 39 to 106 min (mean = 63 min/copulation, SD = 20.6). Both the males and the females proved able to copulate on more than one occasion. Finally, we described the morphology and size of the eggs of this species, indicating some parameters pertaining to the clutch, such as maximum fecundity encountered (357 eggs per female), the maximum number of clutches per female (n = 4), and the number of eggs per clutch (mean = 87.7, range = 22–195).
Davies, M. S. & Hatcher, A. M. 1998: The energy budget: a useful tool? — Ann. Zool. Fennici 35: 231–240.
Studies of energy flow and allocation in biological systems often result in the production of energy budgets. Our aim is to describe the potential mis-representations that energy budgets can produce and draw together the various criticisms levied at energy budgets. While such budgets purport to represent accurately energy allocation we, by discussing the literature, propose that many offer little. This is because in practice they rarely reflect actual energy relationships due to problems with their empirical derivation. These problems include both the omission of some energy budget terms (such as dissolved organic matter, non-lethal predation and metabolic faecal loss) and their underestimation (e.g. mucus production). Recalculation of budgets to account for these terms often results in new conclusions being drawn. Moreover, problems of extrapolation of measurements made in the laboratory to the field, coupled with misconceptions over the expression of temporal and spatial variation in budget terms, produce budgets that are both approximate and specific to an individual or population at the time each budget is constructed. In addition, the set of assumptions that are used in the construction of one budget are rarely the same as those for another and so budgets should be used with extreme care in comparative studies. We suggest that energy budgets have little value in the context of other studies and are of interest and value only as descriptors under a set of what should be well-defined assumptions. We urge caution in their use and propose that more modest studies of energy allocation with precise goals are more appropriate.
Danielsson, I. 1998: Mechanisms of sperm competition in insects. — Ann. Zool. Fennici 35(4): 241–257.
Sperm competition has been demonstrated in a variety of insects and is, in addition to ecological resource distribution and sex ratios, generally believed to play a major role in the evolution of insect reproductive strategies and mating systems. In this paper, I review the main theories and some of the empirical evidence regarding sperm competition in insects. Sperm utilization is shaped by selection on both males and females, sometimes in opposite directions. Here I focus mainly on adaptive mechanisms for sperm priority and paternity assurance, and consequences of such adaptations for females. I also evaluate the importance of the conflicts between the sexes for the evolution of mating behaviour from existing theory and available empirical evidence. Some urgent research areas for future workers are suggested. An explanation for the large intraspecific variation in last male sperm priority is still lacking. To this end, we need detailed studies of the mechanisms of sperm usage within the female, and to what extent females influence postcopulatory fertilization processes.