Grim, T. 2007: Equal rights for chick brood parasites. — Ann. Zool. Fennici 44: 1–7.

Evolutionary interactions between brood parasites (e.g. cuckoos) and their hosts (e.g. small songbirds) became an important model for the study of coevolution, recognition and other subjects central to evolutionary biology. I argue that both primary literature and textbooks provide an unequal picture of brood parasite–host relationships: they make an impression that hosts can defend against parasite only at the egg stage but not at the nestling stage. However, the general impression that chick discrimination is either very rare or even non-existent does not follow from available data — it is studies of chick-related host adaptations which are rare. Using quantitative data on publication and citation rates of egg vs. chick studies I show that there is a strong inequality in favour of egg studies and against chick studies in respect to both research effort (number of studies, number of model host species, studies sample sizes) and citation rates. This bias is apparent in both observational and experimental studies. I argue that current poor knowledge of chick discrimination and mimicry can hardly be explained by logistic obstacles. Both theoretical frameworks and experimental designs were developed and successfully used in several studies of parasite chicks. I suggest that chick discrimination and mimicry should become a priority issue in brood parasitism research in the future to reach a more balanced view of host–parasite interactions.

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Vepsäläinen, V., Pakkala, T., Piha, M. & Tiainen, J. 2007: The importance of breeding groups for territory occupancy in a declining population of a farmland passerine bird. — Ann. Zool. Fennici 44: 8–19.

We studied the relationships between the occupancy of territory sites and environmental and behaviour-related factors in a declining farmland bird, the ortolan bunting Emberiza hortulana, in southern Finland in 1984–2003. We investigated the dependence of different factors on population density. The surrounding breeding group positively affected the occupation frequency of territory sites before and after the population crash. Bush- or tree-covered ditches and springtime non-vegetated fields also had positive effect on territory site occupancy. We suggest that large breeding groups, and obvious conspecific attraction, give indications of favourable breeding locations. Habitat deterioration may have pronounced consequences for local populations, in which the breeding group tends to be the unit of population dynamics. The results suggest that for conservation of the ortolan bunting, the maintenance and improvement of structurally and biologically diverse habitats is vital, since tendency to breed in groups apparently makes the species more sensitive to habitat changes than many other farmland species.

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Piha, M., Lindén, A., Pakkala, T. & Tiainen, J. 2007: Linking weather and habitat to population dynamics of a migratory farmland songbird. — Ann. Zool. Fennici 44: 20–34.

Although factors influencing population fluctuations of migrant birds have been studied intensively, few studies have applied autoregressive modelling in linking monitoring data to essential factors from both breeding and wintering areas. We studied the effects of temporal variation in habitat composition and weather conditions on population dynamics of the skylark Alauda arvensis in southern Finland in 1984–2003 through autoregressive modelling and Monte Carlo testing of simulated time-series. The amount of grassland habitats explained well the general trends in skylark population development. Rainfall had a negative effect on the population growth in breeding areas, but a positive effect in wintering areas. There was also evidence for first order negative density dependence. Our results suggest that intrinsic and extrinsic factors simultaneously included in a population dynamical model, can improve the statistical visibility of both factors. The Monte Carlo approach presented here can be useful in many studies involving strongly autocorrelated time-series.

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Surmacki, A. & Stepniewski, J. 2007: Do weather conditions affect the dynamics of bearded tit Panurus biarmicus populations throughout the year? A case study from western Poland. — Ann. Zool. Fennici 44: 35–42.

Climate change is considered to be one of the factors explaining a recent increase of bearded tit populations. To test this hypothesis, the effect of weather conditions on breeding and wintering populations in western Poland between 1986 and 2005 was studied. Weather did not influence annual changes in the breeding population, whereas non-breeding numbers were positively associated with spring and autumn temperatures. There was a slight trend for earlier egg laying related to higher March–April temperatures. These results suggest that the bearded tit may potentially benefit from climate warming through a prolonged breeding season which in turn could enable more broods to be raised. This conjecture was supported by the fact that the bearded tit showed a strong tendency to start breeding early, well before conditions for maximal clutch size, breeding success and egg volume occurred.

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Frick, H., Nentwig, W. & Kropf, C. 2007: Influence of stand-alone trees on epigeic spiders (Araneae) at the alpine timberline. — Ann. Zool. Fennici 44: 43–57.

We studied community composition and activity densities of spiders around stand-alone Norway spruce at the alpine timberline with respect to three interrelated parameters: (1) relative distance from tree trunk, (2) branch-, and (3) vegetation cover. Pitfall traps were positioned in an inner distance range (close to tree trunk), a median, and an outer distance range (at the outer limit of branch cover). Community composition: Linyphiid species numbers increased significantly towards the tree trunks where the branch cover was high, whereas lycosid and gnaphosid species numbers increased towards the edge where branch cover was low. Activity densities: 11 out of 14 species were significantly correlated with the relative distance to the tree trunk, ten with the branch cover, and two with vegetation cover. Open-land species preferred the outer distance range and forest species the inner distance range. Caracladus avicula is probably a habitat specialist of the alpine timberline.

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Fefferman, N. H. & Ng, K. L. 2007: The role of individual choice in the evolution of social complexity. — Ann. Zool. Fennici 44: 58–69.

Constant re-evaluation of social affiliations and shifting social network structures can profoundly affect the adaptive fitness of individuals within a population, as well as yielding super-additive effects felt by the population as a whole. To evaluate the impact of different social affiliation choices, and the relative ability of individuals to correctly assess the success of other individuals, we have created a set of mathematical models based on network centrality measures. We choose the hypothetical measures of "popularity", "closeness" and "betweenness" to examine the resulting self-organizations of social groups. Our findings suggest that some different types of social behaviors can lead to the same levels of stability and organizational success, suggesting the possibility that complex organizations could have evolved from simpler ones without any change in the selective pressures acting on the population.

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Saastamoinen, M., van Nouhuys, S., Nieminen, M., O'Hara, B. & Suomi, J. 2007: Development and survival of a specialist herbivore, Melitaea cinxia, on host plants producing high and low concentrations of iridoid glycosides. — Ann. Zool. Fennici 44: 70–80.

The Glanville fritillary butterfly (Melitaea cinxia) in Finland feeds on the plants Plantago lanceolata and Veronica spicata. These two plant species are distributed heterogeneously and both vary spatially and temporally in iridoid glycoside concentrations. We investigated the associations of plant species and iridoid glycoside (aucubin and catalpol) concentrations with weight, development rate and survival of larvae of the Glanville fritillary under laboratory conditions. In one experiment we compared the performance of split brood groups of larvae feeding on the two plant species collected from natural populations. In the second experiment larvae were fed P. lanceolata lines laboratory selected for high and low aucubin and catalpol concentrations. Larvae fed V. spicata performed better in terms of survival, weight and growth rate than those feeding on P. lanceolata, regardless of iridoid glycoside concentration. However, in the second experiment iridoid glycoside concentration in P. lanceolata was positively associated with larval performance. High iridoid glycoside concentrations retarded development rate of the first instar larvae, whereas later on the development was accelerated by higher concentrations of these compounds. The spatial and temporal variation of plant species suitability and iridoid glycoside content, and larval family level effects of plant chemistry on performance convey a dynamic ecological and evolutionary relationship between these host plants and their specialized herbivore.

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