Hemborg, C. & Merilä, J. 1999: Reproductive investment and moult-breeding overlap in the collared flycatcher Ficedula albicollis: an experimental approach. — Ann. Zool. Fennici 36: 1–9.
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Getz, W. M. & Schreiber, S. J. 1999: Multiple time scales in consumer-resource interactions. — Ann. Zool. Fennici 36: 11–20.
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Ribera, I., Foster, G. N., Downie, I. S., McCracken, D. I. & Abernethy, V. J. 1999: A comparative study of the morphology and life traits of Scottish ground beetles (Coleoptera, Carabidae). — Ann. Zool. Fennici 36: 21–37.
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Jonzén, N. & Lundberg, P. 1999: Temporally structured density-dependence and population management. — Ann. Zool. Fennici 36: 39–44.
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Van Dongen, S. 1999: Accuracy and power in the statistical analysis of fluctuating asymmetry: effects of between-individual heterogeneity in developmental instability. — Ann. Zool. Fennici 36: 45–52.
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Esteban, M., García-París, M., Buckley, D. & Castanet, J. 1999: Bone growth and age in Rana saharica, a water frog living in a desert environment. — Ann. Zool. Fennici 36: 53–62.
Abstract, Full text (print quality pdf)
Hemborg, C. & Merilä, J. 1999: Reproductive investment and moult-breeding overlap in the collared flycatcher Ficedula albicollis: an experimental approach. — Ann. Zool. Fennici 36: 1–9.
We manipulated brood sizes of 132 pairs of the collared flycatcher to investigate whether or not an investment in reproduction was traded against an investment and timing of the post-nuptial moult. Our manipulations did not affect the probability of moult-breeding overlap in males, and there was no effect on their moult scores at fledging time of the young. Males and young birds initiated moult earlier than females and old birds, respectively. Very few females started moulting during the period of nestling care. Reproductive success in terms of recruitment rate of fledglings was independent of parental moult stage during reproduction, which indicates that the manipulation did not induce a trade-off between moult and post-fledging care. Furthermore, the survival probability of adults was independent of brood size manipulations and their moult stage at fledging time. Thus, our brood size manipulations showed no evidence for a trade-off between reproductive and moult investments in the collared flycatcher.
Getz, W. M. & Schreiber, S. J. 1999: Multiple time scales in consumer-resource interactions. — Ann. Zool. Fennici 36: 11–20.
Arguments regarding the appropriate form for the rate at which consumers extract biomass from resource populations hinge on relative time scales of underlying processes. Some ecologists argue that, because differential equation models imply instantaneous rates of change, time scale arguments do not hold. Here we point out that this reasoning is fallacious. We define three natural time scales for consumer-resource interactions and demonstrate, using asymptotic methods of analysis, how relative differences in these scales lead to the formulation of models with qualitatively distinct dynamics. Further, we identify time scale and resource heterogeneity assumptions that constrain the R* competition rule (i.e., the competitor that suppresses the resource to the lowest density excludes all other competitors), as well as clarify the dichotomy between Schoener's models of competition for overlapping and for partitioned resources.
Ribera, I., Foster, G. N., Downie, I. S., McCracken, D. I. & Abernethy, V. J. 1999: A comparative study of the morphology and life traits of Scottish ground beetles (Coleoptera, Carabidae). — Ann. Zool. Fennici 36: 21–37.
We test whether there is a significant correspondence between the morphology of ground beetles and their life traits, as measured with phylogenetic independent contrasts. Seven life traits of known functional importance, and the morphospace defined by 87 species of ground beetles occurring in Scottish agricultural land were investigated using two different systematic arrangements as an approximation to the phylogeny of the group. The morphospace was previously defined with the first three multivariate ordination axes of 13 quantitative measures of the shape of the body, hind legs, eyes and antennae, plus total length as a surrogate measurement of size. Results were found to be largely coherent irrespective of the classification used, demonstrating the robustness of the associations despite possible changes in the knowledge of the detailed phylogeny of the group. The first ordination axis of the morphospace was significantly related to diet, and the second to diel activity. When individual morphological measures were compared, diet of the adult was most significantly related with length of the hind legs. The variable most related with diel activity was the length of the antennae. Species with overwintering larvae and species with two year cycles were larger than species which either overwinter solely as adults or which always complete their development in one year.
Jonzén, N. & Lundberg, P. 1999: Temporally structured density-dependence and population management. — Ann. Zool. Fennici 36: 39–44.
We used a simple discrete-time population model to investigate how temporally structured density-dependence influences a population's response to loss due to harvesting. We assumed that reproduction is a relative discrete event in time, followed by density-dependent mortality and then harvesting, or followed by harvesting and then density-dependent mortality. Such an ordering of events in time may have profound influences on the dynamics of the population. The extra mortality due to harvesting may either be additive or compensatory depending on the strength of the density-dependence and the ordering of events. Population stability is also strongly affected by the temporal structure of density-dependence. Moreover, the yield and the (unconstrained) optimal harvest rate will vary depending on when harvesting occurs in the annual cycle. We argue that a correct identification of the temporal structure of density-dependence may be of great importance for understanding population dynamics in general and population management in particular.
Van Dongen, S. 1999: Accuracy and power in the statistical analysis of fluctuating asymmetry: effects of between-individual heterogeneity in developmental instability. — Ann. Zool. Fennici 36: 45–52.
A non-exhaustive literature search revealed that samples often show heterogeneity in the underlying developmental instability. As a consequence, the distribution of the signed asymmetry is leptocurtic. Simulations presented in this paper showed that a recently developed method to test heterogeneity in FA (likelihood ratio test of REML mixed regression models) has inflated type I error rates, whereas Levene's test suffered power reduction. The latter appeared to be the result of a lower accuracy of the estimation of population level FA. These effects became stronger with increasing leptokurtisis. In contrast, the estimation of R became more accurate and precise with increasing heterogeneity (and thus expected value of R). The estimation of small values of R is subject to extremely large sampling variation and were biased towards lower values. Implications for the analysis of FA at the individual and population level are discussed.
Esteban, M., García-París, M., Buckley, D. & Castanet, J. 1999: Bone growth and age in Rana saharica, a water frog living in a desert environment. — Ann. Zool. Fennici 36: 53–62.
The structure and the histological expression of annual bone growth marks of Moroccan water frogs (Rana saharica) from an arid climate region (northern edge of the Sahara desert) differ from the pattern observed in water frogs from temperate climate regions. At early ages, when growing rates are high, the osteogenic activity of the froglets never stops completely, and during the resting period the histological marks formed in the bone are mostly annuli. However, growth marks formed in older individuals are mostly well defined thin LAGs, which correspond to a complete stop in of osteogenesis. Males and females mature when they are two years old. The oldest males and females were six years old. One-year-old froglets showed a wide range in body size (22.4 to 40.9 mm) associated with an extended period of metamorphosis. Considering LAG diameter as the diameter of the phalange at a given age, we obtained successive phalange diameters for each individual corresponding to each year of its life. The diameter of the LAG1 of adults of Rana saharica is significantly larger than the diameter of the LAG1 of one year old juveniles. We found similar results studying the tibiofibulae of the sister taxon of R. saharica, R. perezi. Larger froglets were thus more successful than smaller ones in generating the adult samples suggesting the existence of size mediated selection. Extended breeding periods, which allow various metamorphosis peaks along the year, would be apparently disadvantageous for the species, since only froglets of a few subcohorts would be able to survive. However, this strategy could be of importance in Mediterranean and desert areas where local conditions change dramatically from year to year.