Forsman, A. 1997: Thermal capacity of different colour morphs in the pygmy grasshopper Tetrix subulata. — Ann. Zool. Fennici 34: 145–149.
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Schandorff, S. 1997: Developmental stability and skull lesions in the harbour seal (Phoca vitulina) in the 19th and 20th Centuries. — Ann. Zool. Fennici 34: 151–166.
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Schandorff, S. 1997: Developmental stability and the harbour seal epizootic in 1988. — Ann. Zool. Fennici 34: 167–175.
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Marttila, O., Saarinen, K. & Jantunen, J. 1997: Habitat restoration and a successful reintroduction of the endangered Baton Blue butterfly (Pseudophilotes baton schiffermuelleri) in SE Finland. — Ann. Zool. Fennici 34: 177–185.
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Pertoldi, C., Loeschcke, V., Madsen, A. B. & Randi, E. 1997: Developmental stability in the Eurasian Otter (Lutra lutra) in Denmark. — Ann. Zool. Fennici 34: 187–196.
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Jonsson, P. & Silverin, B. 1997: The estrous cycle in female wood mice (Apodemus sylvaticus) and the influence of the male. — Ann. Zool. Fennici 34: 197–204.
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Stigzelius, J., Laine, A., Rissanen, J., Andersin, A.-B. & Ilus, E. 1997: The introduction of Marenzelleria viridis (Polychaeta, Spionidae) into the Gulf of Finland and the Gulf of Bothnia (northern Baltic Sea). — Ann. Zool. Fennici 34: 205–212.
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Tambets, M., Mölsä, H. & Saat, T. 1997: Effect of triiodthyronine on in vitro maturation of vendace (Coregonus albula) oocytes under unfavourable influences. — Ann. Zool. Fennici 34: 213–216.
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Forsman, A. 1997: Thermal capacity of different colour morphs in the pygmy grasshopper Tetrix subulata. — Ann. Zool. Fennici 34(3): 145–149.
I examined the relative importance of colour pattern, body size and shape for thermoregulation by experimentally subjecting adult female Tetrix subulata belonging to four different colour morphs (black, striped, brown, and white) to augmented irradiation levels. The results revealed significant variation in temperature excess (i.e., the difference between ambient and body temperature) among colour morphs, with black individuals having a mean temperature excess 49% greater than that of white individuals. Temperature excess was not significantly influenced by overall body size (measured as principal component 1 (PC1)) but increased with increasing values of PC2, suggesting that stout bodied individuals attained higher body temperatures than did individuals with low body mass relative to surface area. These results show that coloration may play an important role in determining body temperatures of grasshoppers exposed to direct irradiation, and suggest that reproductive females may be able to maintain higher body temperatures than non-reproductive females and males.
Schandorff, S. 1997: Developmental stability and skull lesions in the harbour seal (Phoca vitulina) in the 19th and 20th Centuries. — Ann. Zool. Fennici 34: 151–166.
Developmental stability in the Kattegat population of harbour seal (Phoca vitulina) was assessed to determine whether reduced developmental stability occurred prior to the epizootic in 1988 and possibly predicted the high mortality. As a measure of developmental stability the fractal dimension of the paired maxillo palatinae suture was calculated and the degree of fluctuating asymmetry in teeth, foramina and the paired suture was estimated in 361 skulls. Moreover prevalence of three pathological changes of the skull was investigated. Reduced developmental stability and higher prevalence of pathological changes were associated with a dramatic increase in pollution after World War II. Reduced developmental stability occurred prior to the epizootic, although young seals born after levels of pollution started to decrease tended to be developmentally more stable. No relationship was found between pathological changes and developmental stability.
Schandorff, S. 1997: Developmental stability and the harbour seal epizootic in 1988. — Ann. Zool. Fennici 34: 167–175.
Developmental instability of harbour seals (Phoca vitulina) that died during the epizootic in 1988 in the Kattegat was compared with that of the population prior to the epizootic to investigate whether animals that died were the developmentally less stable individuals in the population. As an assessment of developmental instability the fractal dimension of the paired maxillo palatinae suture was calculated and the degree of fluctuating asymmetry in teeth, foramina and the paired suture was estimated in a total of 240 skulls. Moreover, prevalences of three pathological changes of the skull were compared. No difference was found in developmental instability or prevalence of skull lesions between animals that died in the epizootic and estimates from the population prior to the epizootic. The lack of difference could be in accordance with the suggestion that organochlorines had an influence on mortality during the epizootic. Levels of organochlorines have decreased in the last decade before the epizootic, and thereby could have equalized differences in levels of developmental stability.
Marttila, O., Saarinen, K. & Jantunen, J. 1997: Habitat restoration and a successful reintroduction of the endangered Baton Blue butterfly (Pseudophilotes baton schiffermuelleri) in SE Finland. — Ann. Zool. Fennici 34: 177–185.
We reintroduced the endangered Baton Blue butterfly (Pseudophilotes baton schiffermuelleri, Bergsträsser) from its last known Finnish population to a site where it had become extinct. The butterfly is associated with dry and open eskers, but because of drastic habitat degradation only one population is known to have survived in Finland. The main reason for habitat loss is succession of pine forests. The last verified records of the species at the site of reintroduction date from 1984. The habitat was managed by the selective logging of pines in 1992. In 1994, after vegetation followups, 10 female baton blues were translocated. The introduced population was studied with the mark–recapture method in 1995–1996. Its size increased during this period to ca. 50 butterflies in 1996. Reintroduction, accomplished in close cooperation with forest industry, administration authorities and environmentalists, has diminished the probability of extinction of the baton blue in Finland.
Pertoldi, C., Loeschcke, V., Madsen, A. B. & Randi, E. 1997: Developmental stability in the Eurasian Otter (Lutra lutra) in Denmark. — Ann. Zool. Fennici 34: 187–196.
Fluctuating asymmetry (FA) as expressed in metric and meristic skull traits was analysed in a sample of 172 otters collected in Denmark between 1861 and 1994. Tissue levels of organochlorine pesticide residues and PCBs were determined and the correlation between contaminant concentration and FA was tested. A significant correlation was found between FA in different traits and the year of collection, but there was no significant correlation between FA and the concentration of contaminants. These results suggest that factors other than pesticides have affected the developmental stability of skulls in the Danish otter population. Among these, a population bottleneck following habitat fragmentation is discussed as a possible cause.
Jonsson, P. & Silverin, B. 1997: The estrous cycle in female wood mice (Apodemus sylvaticus) and the influence of the male. — Ann. Zool. Fennici 34: 197–204.
Based on studies of vaginal smears from wild-caught Swedish wood mice, females with three types of estrous cycles were identified: females with a continuous estrus; females with an estrous cycle between 6 and 11 days in length; and females that only rarely showed signs of estrus. We tested the pregnancy rates and how stable the estrus patterns were among the females. Ninety-one percent of the females with a continuous estrus pattern became pregnant, 50% of the females showing a cyclic estrus pattern, and 60% of the females showing an infrequent estrus. However, pregnancy occurred about 2 weeks later in females with an infrequent estrus pattern. Some females changed their estrus pattern after pregnancy, indicating that estrus patterns are not fixed.
Stigzelius, J., Laine, A., Rissanen, J., Andersin, A.-B. & Ilus, E. 1997: The introduction of Marenzelleria viridis (Polychaeta, Spionidae) into the Gulf of Finland and the Gulf of Bothnia (northern Baltic Sea). — Ann. Zool. Fennici 34: 205–212.
The spionid polychaete Marenzelleria viridis (Verrill 1873) was for the first time observed in the Finnish coastal waters at the entrance of the Gulf of Finland in 1990. During 1990–1993 M. viridis expanded its distribution into the eastern parts of the Gulf of Finland and into the southern part of the Gulf of Bothnia. Its introduction into the Baltic Sea has probably occurred through ship transport, as all the first findings are connected to harbour areas. Although the abundance and biomass of M. viridis is comparatively low the species seems to have become a permanent member of the macrozoobenthos in the northern Baltic.