Fanouraki, E., Laitinen, J. T., Divanach, P. & Pavlidis, M. 2007: Endocrine regulation of skin blanching in red porgy, Pagrus pagrus. — Ann. Zool. Fennici 44: 241–248.

Previous research on red porgy, Pagrus pagrus , has shown that physiological colour change does not depend on changes in plasma cortisol or [alpha]-MSH. The purpose of this study was to identify the endocrine mechanism responsible for skin blanching in fish exposed to white background. There was no significant difference in serum cortisol, glucose, lactate, thyroid hormones, or plasma epinephrine concentration between black and white-background-adapted fish. Mean daily plasma melatonin concentration was significantly higher in black- (41.29 ? 2.46 pg ml^–1) than white-background-exposed fish (32.07 ? 1.26 pg ml^–1) while mean plasma norepinephrine was almost fivefold higher in white- (6.26 ? 1.57 ng ml^–1) than in black-background-adapted fish (1.01 ? 0.34 ng ml^–1). Skin melanin concentration did not differ significantly between the experimental groups. Our study indicates that skin blanching in red porgy is mediated through norepinephrine release.

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Zabala, J., Zuberogoitia, I. & Martínez-Climent, J. A. 2007: Spacing pattern, intersexual competition and niche segregation in American mink. — Ann. Zool. Fennici 44: 249–258.

Many animals, especially mustelids, show a spacing pattern known as intrasexual territoriality in which territorial animals defend areas against individuals of the same sex and there is extensive overlap between sexes. It has been argued that this overlap leads to sharing of food resources between territorial individuals of different sexes which has a net cost for territorial individuals. Several mechanisms have been proposed to reduce competition between sexes, many of them derived from sexual dimorphism, which is closely related to intrasexual territoriality. Among the suggested mechanism is spatial segregation between animals with overlapping areas, although it remains largely untested. We hypothesized that sexual spatial segregation in mustelids could be a consequence of a niche partition in habitat between sexes due to different optimums. We conducted a fine-grained radio tracking survey of seven feral American minks in winter. We compared home ranges, relative spatial positions and characteristics of radio-locations of different sexes. We also considered relative distances between simultaneous locations of overlapping individuals to test for dynamic territorial interactions. There were differences in the home range composition of males and females, and in their relative spatial location, proving spatial segregation between sexes. The comparison of locations showed that females preferred smaller streams as opposed to males that preferred large streams. In addition relative spatial position of female locations was independent of location of males in overlapping pairs, suggesting niche segregation caused by different sexual habitat preferences. Sexual habitat segregation is discussed as a powerful means of avoiding intersexual competition in species exhibiting intrasexual territoriality as a spacing pattern.

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Zhan, A. B., Bao, Z. M., Hui, M., Wang, M. L., Zhao, H. B., Lu, W., Hu, X. L. & Hu, J. J. 2007: Inheritance pattern of EST-SSRs in self-fertilized larvae of the bay scallop Argopecten irradians. — Ann. Zool. Fennici 44: 259–268.

Null allele and marker segregation distortion are considered to be common in bivalve molluscs. To facilitate genetic analysis of the bay scallop, the inheritance patterns of nineteen EST-SSRs were tested in four self-fertilized families. While the filial genotypes in twelve segregations conformed to Mendelian inheritance, three locus-family cases showed the significant departure. Two loci confirmed Mendelian expectations when null alleles were considered. The molecular basis of null alleles was detected by redesigning primers in the external flanking regions, and single nucleotide mutations in primer annealing sites were responsible for the null allele. Based on our results, the inheritance pattern and null allele of novel microsatellite markers should be further tested before using them for population studies and parentage assignment in the bay scallop. Additionally, six markers were recommended as members of a standard marker panel for use in population genetic and parentage studies.

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Posluszny, M., Pilot, M., Goszczynski, J. & Gralak, B. 2007: Diet of sympatric pine marten (Martes martes) and stone marten (Martes foina) identified by genotyping of DNA from faeces. — Ann. Zool. Fennici 44: 269–284.

Martes martes and Martes foina occur sympatrically in most of Europe. Little is known about differences between trophic niches of these species, because martens are difficult to observe and it is impossible to distinguish between scats of both species based on their morphological features. To resolve this problem, we used DNA extracted from faeces for species identification. This method allowed us to compare the diet of the two species in the area of their sympatric occurrence in central Poland. We analysed the composition of 287 scats of stone martens and 155 of pine martens. Both species fed mainly on small rodents, birds and fruits. Although the trophic niches of both martens highly overlapped, we found significant quantitative differences in their food composition. Pine martens fed more frequently on rodents and birds, and stone martens on fruits and insects. These differences were also visible in the seasonal perspective. Although both martens exploited the same forest habitat, genetic identification of faeces allowed us to indicate significant differences in the diet of these closely related species.

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Helama, S. & Valovirta, I. 2007: Shell morphometry, pre-mortal taphonomy and ontogeny-related growth characteristics of freshwater pearl mussel in northern Finland. — Ann. Zool. Fennici 44: 285–302.

Museum collection of endangered freshwater pearl mussel (Margaritifera margaritifera) shells was studied. The ontogenetic ages of the mussels were estimated to be between 12 and 178 years. Information from shell increments, morphometry and taphonomy was combined into age-dependent life-trait reconstructions that were modelled using linear and non-linear growth functions. Nearly all the life-trait records were best explained by non-linear models and only the shell weight was best modelled by the linear growth function. In accordance with the previously set theory about the plasticity of the species life-traits and their dependence on climate and hydrogeochemistry, the shells with northern origin reached relatively large sizes with slow growth rate. The ontogenetic age could be statistically predicted using the composite dataset of life-trait information. Based on the morphometrics, we theorized that the over 60-year-old mussels are better hedged against the potential hydrological changes resulting from climat change than younger individuals.

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Sousa, R., Dias, S. & Antunes, C. 2007: Subtidal macrobenthic structure in the lower Lima estuary, NW of Iberian Peninsula. — Ann. Zool. Fennici 44: 303–313.

Seasonal variation of the subtidal macrobenthic community in the lower Lima estuary was investigated at twelve sites. Univariate and multivariate analyses were used to establish patterns in species distribution, abundance, and biomass; and to determine the influence of site and season on the subtidal macrobenthic community. A total of 101 macrobenthic taxa were identified and values of diversity were generally low indicating a high degree of dominance of few species. Average abundance and biomass per site ranged from 46.7 to 8060 ind. m^–2 and 0.56 to 28.96 g AFDW m^–2 , respectively. Abra alba was most abundant and had the highest biomass. Multivariate analysis revealed four distinct groups. Each group was represented by a specific species composition and characterised by different environmental conditions, in particular, the sediment characteristics and salinity. Abundance/biomass comparison (ABC) indicated that the lower part of the estuary is under environmental stress and is dominated by opportunistic species. The subtidal macrobenthic community of the lower Lima estuary differed between sites but not between seasons of the year.

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Moreno-Rueda, G. & Pizarro, M. 2007: Snake species richness and shrubland correlate with the short-toed eagle (Circaetus gallicus) distribution in south-eastern Spain. — Ann. Zool. Fennici 44: 314–320.

The short-toed eagle (Circaetus gallicus) is a trophic specialist with a diet based almost exclusively on ophidians. In this work, the distribution of this eagle in south-eastern Spain taken from national atlases, is analysed in relation to environmental variables. The results show that the short-toed eagle is distributed primarily in shrublands, probably because there it can easily locate and capture its prey. It also prefers an intermediate cover of forest, because it needs trees for nesting. Lastly, there was a correlation, after statistically controlling for other variables, between snake species richness and eagle presence. It is possible that snake species richness favours the presence of this raptor, as it preys on different species. Alternatively, because this raptor preys preferentially on dominant ophidians in the study area, it is also possible that the presence of this eagle favours snake diversity by a top-down regulation on the ophidian community.

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