Höglund, J. 2003: Lek-kin in birds — provoking theory and surprising new results. — Ann. Zool. Fennici 40: 249–253.
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Topping, C., Østergaard, S., Pertoldi, C. & Bach, L. A. 2003: Modelling the loss of genetic diversity in vole populations in a spatially and temporally varying environment. — Ann. Zool. Fennici 40: 255–267.
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Merilä, J., Sheldon, B. C. & Griffith, S. C. 2003: Heterotic effects on fitness in a wild bird population. — Ann. Zool. Fennici 40: 269–280.
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Ahtiainen, J. A., Alatalo, R. V., Mappes, J. & Vertainen, L. 2003: Fluctuating asymmetry and sexual performance in the drumming wolf spider Hygrolycosa rubrofasciata. — Ann. Zool. Fennici 40: 281–292.
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Blackledge, T. A., Binford, G. J. & Gillespie, R. G. 2003: Resource use within a community of Hawaiian spiders (Araneae: Tetragnathidae). — Ann. Zool. Fennici 40: 293–303.
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Nordengren, C., Hofgaard, A. & Ball, J. P. 2003: Availability and quality of herbivore winter browse in relation to tree height and snow depth. — Ann. Zool. Fennici 40: 305–314.
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Höglund, J. 2003: Lek-kin in birds — provoking theory and surprising new results. — Ann. Zool. Fennici 40: 249–253.
I review studies relating to the question of whether kin selection is prevalent on leks and may help to explain their evolution. This is not a comprehensive review, instead my aim is to give an account of how kin selection became incorporated in lek research. I hope to show that theoretical modelling provoked empirical research, which in this particular case substantiated many of the the theoretical predictions. However, some recent empirical studies have found results indicating kin clustering beyond what was anticipated by theory. The debate on the importance of kin selection and kin clustering in the case of leks is still in its infancy. New models and data will no doubt spur further research in this area.
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Topping, C., Østergaard, S., Pertoldi, C. & Bach, L. A. 2003: Modelling the loss of genetic diversity in vole populations in a spatially and temporally varying environment. — Ann. Zool. Fennici 40: 255–267. Back to the top
Merilä, J., Sheldon, B. C. & Griffith, S. C. 2003: Heterotic effects on fitness in a wild bird population. — Ann. Zool. Fennici 40: 269–280. Back to the top
Ahtiainen, J. A., Alatalo, R. V., Mappes, J. & Vertainen, L. 2003: Fluctuating asymmetry and sexual performance in the drumming wolf spider Hygrolycosa rubrofasciata. — Ann. Zool. Fennici 40: 281–292. Back to the top
Blackledge, T. A., Binford, G. J. & Gillespie, R. G. 2003: Resource use within a community of Hawaiian spiders (Araneae: Tetragnathidae). — Ann. Zool. Fennici 40: 293–303. Back to the top
Nordengren, C., Hofgaard, A. & Ball, J. P. 2003: Availability and quality of herbivore winter browse in relation to tree height and snow depth. — Ann. Zool. Fennici 40: 305–314.
Altering environmental conditions affects the genetic composition of populations via demographic and selective responses by creating of variety of population sub-structuring types. Classical genetic approaches can predict the genetic composition of populations under long-term or structurally stable conditions, but exclude factors such as animal behaviour, environmental structure, and breeding biology, all of which influence genetic diversity. Most populations are unique in some of these characteristics, and therefore may be unsuitable for the classical approach. Here, an alternative approach using a genetically explicit individual-based model (IBM) coupled to a dynamic landscape model was used to obtain measures for the genetic status of simulated vole populations. The rate of loss of expected heterozygosity (He) was calculated for simulated populations using two levels of spatial and temporal heterogeneity. Results showed that both spatial and temporal heterogeneity exerted an influence on the rate of loss of genetic diversity, but the precise effect was a balance between the effects of population sub-structuring, the frequency of founder effects and population size. These were in turn related to habitat availability and their influence on vole behaviour. Interaction between spatial and temporal dynamics altered the ratio of effective population size to census size. This indicates an altered reproductive potential, crucial in conservation biology applications. However, when the loss of heterozygosity was corrected for the harmonic mean of the population size, the rate of loss was almost identical in the four scenarios. Unlike classical genetic models, IBMs are flexible enough to mimic real population processes under a range of environmental and behavioural conditions. We conclude that IBMs incorporating explicit genetics provide a promising new approach to the evaluation of the effect of animal behaviour, and random and man-induced events on the genetic composition of populations. They also provide a new platform from which to investigate the implication of real world deviations from assumptions of traditional genetic models.
The role of genetic variation in determining fitness in natural populations has been enigmatic for decades. Both theoretical and empirical work suggest that additive genetic contributions to fitness variation are small, whereas observations of inbreeding depression suggest that non-additive genetic contributions to fitness can sometimes be large. We analysed associations between genetic variability at a small number of microsatellite loci and fitness in a natural population of the collared flycatcher Ficedula albicollis, and related these to estimates of additive genetic contributions to the same traits. We found strong single-locus associations between an intra-locus measure of variability (d2) and variables related to fitness. These heterotic effects were sex-specific, being found only in males, and variation at this locus explained as much as 11% of the variance in male lifetime reproductive success. The size of the heterotic effect on a trait depended on how closely that trait was related to fitness, and there was a negative relationship between the size of the heterotic effect and the proportion of a trait's variance due to additive genetic variance. One possibility is that the heterosis results from introgression due to hybridization with the closely related pied flycatcher F. hypoleuca. Our results provide evidence that genetic contributions to fitness can be important in outbred populations.
Recently, there has been much interest in estimating fluctuating asymmetry (FA) of morphological traits as a short-cut measure of individual quality. FA deals with small differences around the symmetry value of zero. Thus, measurement error is often relatively large. However, repeated measurements and large sample sizes allow reliable estimates of FA that can be corrected for errors. The purpose of this study was two-fold: at the biological level, we examined with a large sample size (N = 804) whether pedipalp FA could be used as a short-cut measure of individual quality in the wolf spider Hygrolycosa rubrofasciata. This was done by estimating how strongly FA correlates with male sexual performance, i.e. drumming rate and mobility. At the statistical level, we examined how the deflating effect of measurement error could be eliminated to get unbiased correlations between FA and any repeatable trait. We also examined which is the more economical way to get accurate population-level estimates of FA–trait associations, to increase sample size or the number of within-subject repeats. Our results show that there was a very weak, but significant negative relationship between pedipalp FA and mobility (Kendall's partial rk = –0.086). However, this value inevitably underestimates the true relationship, given the large measurement error. It is possible to estimate the unbiased relationship by correcting the above correlation coefficient with effective reliability estimates of both FA and sexual performance. After the correction, the unbiased relationship between FA and mobility was r = –0.183. Our results indicate that FA is weakly related to male sexual performance in H. rubrofasciata. Our results also show that leptokurtosis, which is characteristic of signed FA distributions, was entirely caused by 17 outlier individuals. This indicates that large sample sizes are important to illustrate the true between-individual heterogeneity in FA. Furthermore, our power analysis indicates that it pays to measure more individuals than to increase the number of within-subject repeats to obtain accurate population-level estimates of FA-trait associations.
We examined the relationship between web architecture, microhabitat utilization, and prey capture for five sympatric species of spiders (Araneae: Tetragnathidae: Tetragnatha Latreille) in Waikamoi Preserve, East Maui, Hawaiian Islands. We found that each species of spider built webs that differed from its congeners in one or more architectural and microhabitat features, and that each species also differed in the types of insect prey they captured. Although the causal mechanisms remain to be tested, we suggest that species-specific differences in web building behaviors could account for the differences found in utilization of prey and microhabitat resources. Furthermore, the ability to construct webs with different architectures may be related to the extraordinary diversification of endemic web-building Hawaiian Tetragnatha.
The vertical distribution of biomass, nutrients, and concentrations of secondary defence compounds in the current annual growth of the main winter forage trees (birch and willows) of herbivores was studied in the mountain range of northern Scandinavia. In addition, forage availability in relation to snow accumulation was studied throughout winter. The quantity and quality of forage improved with the height of the trees, i.e. biomass and nitrogen concentrations increased, and fibre decreased. The concentration of defensive compounds increased with height for willow, but decreased for birch. Shoots of willow were of better quality than of birch. The negative effect of the higher levels of total defensive compounds in birch may to some extent be balanced by their higher nutrient content and total forage biomass as compared with that of willow, however willow had more available biomass within the heights browsed by herbivores. Although snow accumulation had significant effects on forage availability, the effects within the entire height range browsed by herbivores were small.