| 1. |
- Brommer, Jon E., et al.
(författare)
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Body size and immune defense of nestling blue tits (Cyanistes Caeruleus) in response to manipulation of ectoparasites and food supply
- 2011
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Ingår i: The AUK. - : Oxford University Press (OUP). - 0004-8038 .- 1938-4254. ; 128:3, s. 556-563
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Tidskriftsartikel (refereegranskat)abstract
- A developing organism faces a dilemma: whether to allocate available resources to building its body structures (growth) or to the development of its immune system. The outcome of this tradeoff is likely to be modified by parasites. We manipulated the abundance of ectoparasitic Hen Fleas (Ceratophyllus gallinae) on nestling Blue Tits (Cyanistes caeruleus) by microwaving nests and subsequently adding 200 Hen Fleas (15 infested nests) or not (16 reduced-infestation nests). In addition, we manipulated the host nestlings' food resources by supplementary feeding 10-15% of daily energy needs to half the nestlings in a nest during the key developmental period (days 2-12). Feather growth (tail and wing length) and hematocrit were reduced by the presence of Hen Fleas, indicating negative effects on nestling development. In comparison to the control nestlings, food-supplemented nestlings aged 16 days were larger (tarsus, residual body mass), but only in reduced-infestation nests (interaction between both treatments). Body size of fed male offspring increased in relation to that of females, but only in the absence of ectoparasites. We hypothesized that supplemented resources are allocated to immune defense when ectoparasites are present, but humoral immune function (total immunoglobulin concentration) and cell-mediated immune defense (phytohemagglutinin response) were not affected by either treatment. Either the nestlings allocated additional resources away from growth (into an unknown developmental component) when parasites were abundant, or the ectoparasites preferentially fed on supplementary-fed host nestlings and thereby equalized the development of soma and immune defense of nestlings despite provision of additional resources.
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| 2. |
- Eeva, Tapio, et al.
(författare)
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Geographical trends in the yolk carotenoid composition of the pied flycatcher (Ficedula hypoleuca)
- 2011
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 165:2, s. 277-287
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Tidskriftsartikel (refereegranskat)abstract
- Carotenoids in the egg yolks of birds are considered to be important antioxidants and immune stimulants during the rapid growth of embryos. Yolk carotenoid composition is strongly affected by the carotenoid composition of the female's diet at the time of egg formation. Spatial and temporal differences in carotenoid availability may thus be reflected in yolk concentrations. To assess whether yolk carotenoid concentrations or carotenoid profiles show any large-scale geographical trends or differences among habitats, we collected yolk samples from 16 European populations of the pied flycatcher, Ficedula hypoleuca. We found that the concentrations and proportions of lutein and some other xanthophylls in the egg yolks decreased from Central Europe northwards. The most southern population (which is also the one found at the highest altitude) also showed relatively low carotenoid levels. Concentrations of beta-carotene and zeaxanthin did not show any obvious geographical gradients. Egg yolks also contained proportionally more lutein and other xanthophylls in deciduous than in mixed or coniferous habitats. We suggest that latitudinal gradients in lutein and xanthophylls reflect the lower availability of lutein-rich food items in the northern F. hypoleuca populations and in montane southern populations, which start egg-laying earlier relative to tree phenology than the Central European populations. Similarly, among-habitat variation is likely to reflect the better availability of lutein-rich food in deciduous forests. Our study is the first to indicate that the concentration and profile of yolk carotenoids may show large-scale spatial variation among populations in different parts of the species' geographical range. Further studies are needed to test the fitness effects of this geographical variation.
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| 3. |
- Lebigre, Christophe, et al.
(författare)
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Limited indirect fitness benefits of male group membership in a lekking species
- 2014
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 23:21, s. 5356-5365
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Tidskriftsartikel (refereegranskat)abstract
- In group living species, individuals may gain the indirect fitness benefits characterizing kin selection when groups contain close relatives. However, tests of kin selection have primarily focused on cooperatively breeding and eusocial species, whereas its importance in other forms of group living remains to be fully understood. Lekking is a form of grouping where males display on small aggregated territories, which females then visit to mate. As females prefer larger aggregations, territorial males might gain indirect fitness benefits if their presence increases the fitness of close relatives. Previous studies have tested specific predictions of kin selection models using measures such as group-level relatedness. However, a full understanding of the contribution of kin selection in the evolution of group living requires estimating individuals' indirect fitness benefits across multiple sites and years. Using behavioural and genetic data from the black grouse (Tetrao tetrix), we show that the indirect fitness benefits of group membership were very small because newcomers joined leks containing few close relatives who had limited mating success. Males' indirect fitness benefits were higher in yearlings during increasing population density but marginally changed the variation in male mating success. Kin selection acting through increasing group size is therefore unlikely to contribute substantially to the evolution and maintenance of lekking in this black grouse population.
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| 4. |
- Morales, Judith, et al.
(författare)
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Variation in eggshell traits between geographically distant populations of pied flycatchers Ficedula hypoleuca
- 2013
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Ingår i: Journal of Avian Biology. - 0908-8857 .- 1600-048X. ; 44:2, s. 111-120
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Tidskriftsartikel (refereegranskat)abstract
- The expression and impact of maternal effects may vary greatly between populations and environments. However, little is known about large-scale geographical patterns of variation in maternal deposition to eggs. In birds, as in other oviparous animals, the outermost maternal component of an egg is the shell, which protects the embryo, provides essential mineral resources and allows its interaction with the environment in the form of gas exchange. In this study, we explored variation of eggshell traits (mass, thickness, pore density and pigmentation) across 15 pied flycatcher populations at a large geographic scale. We found significant between-population variation in all eggshell traits, except in pore density, suggesting spatial variation in their adaptive benefits or in the females' physiological limitations during egg laying. Between- population variation in shell structure was not due to geographic location (latitude and longitude) or habitat type. However, eggshells were thicker in populations that experienced higher ambient temperature during egg laying. This could be a result of maternal resource allocation to the shell being constrained under low temperatures or of an adaptation to reduce egg water loss under high temperatures. We also found that eggshell colour intensity was positively associated with biliverdin pigment concentration, shell thickness and pore density. To conclude, our findings reveal large- scale between-population variation of eggshell traits, although we found little environmental dependency in their expression. Our findings call for further studies that explore other environmental factors (e.g. calcium availability and pollution levels) and social factors like sexual selection intensity that may account for differences in shell structure between populations.
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| 5. |
- Pitala, Natalia, et al.
(författare)
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Costs and Benefits of Experimentally Induced Changes in the Allocation of Growth versus Immune Function under Differential Exposure to Ectoparasites
- 2010
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 5:5, s. e10814-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Ecological immunology has focused on the costs of investment in immunocompetence. However, understanding optimal resource allocation to immune defence requires also identification of its benefits, which are likely to occur only when parasites are abundant. Methodology: We manipulated the abundance of parasitic hen fleas in blue tit (Cyanistes caeruleus) nests, and supplemented their hosts, the nestlings, with methionine (a sulphur amino acid enhancing cell-mediated immunity) during day 3-6. We found a significant interaction between these two experimental factors on the development of immune defences and growth rates. Only in parasitized nests did methionine supplementation boost immune (PHA) response, and did nestling with experimentally increased immunocompetence show a relatively faster growth rate than control nestlings between days 6-9. Hence, the allocation of resources into immune defence and its growth-benefits are apparent only in presence of parasites. The main cost of methionine-induced increased allocation to the immune system was an increase in mortality, independently of ectoparasites. Nestlings in all treatments compensated initial growth reduction and all reached equal body size at day 16 (just prior to fledging), indicating a lack of long-term benefits. In addition, methionine treatment tended (P = 0.09) to lower circulating plasma immunoglobulin levels, possibly indicating a trade-off between the cell-mediated and humoral components of the immune system. Conclusions: We found no strong benefits of an increased investment in immunocompetence in a parasite-rich environment. Any deviation from the growth trajectory (due to changes in allocation induced by methionine) is largely detrimental for survival. Hence, while costs are apparent identifying the benefits of investment in immunocompetence during ontogeny is challenging.
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| 6. |
- Pitala, Natalia, et al.
(författare)
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Ectoparasites help to maintain variation in cell-mediated immunity in the blue tit-hen flea system
- 2009
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Ingår i: Evolutionary Ecology Research. - 1522-0613 .- 1937-3791. ; 11:1, s. 79-94
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Tidskriftsartikel (refereegranskat)abstract
- Hypothesis: Host-parasite interactions have the potential to maintain genetic variation, especially in traits related to defence against parasites. Organism: Blue tit (Cyanistes caeruleus) nestlings. Methods: Rear nestlings in artificially created conditions of low and high abundance of ectoparasitic hen fleas (Ceratophyllus gallinae). Cross-foster siblings between these environments to estimate parasite-induced genotype-environment interactions. Measure components of phenotypic variance in morphology (tarsus length and body mass) and in immune defence (plasma immunoglobulins and cell-mediated immunocompetence). Results: Hen flea infestation lowered growth, cell-mediated immunocompetence, and haematocrit. Genotype-environment interactions were observed in cell-mediated immunocompetence, body mass, and haematocrit, with significant crossing reaction norms for cell-mediated immunocompetence and haematocrit. Immunoglobulin concentrations were unaffected by fleas. Thus, host-parasite interactions constrain the expression and evolvability of some traits, but also create genotype-environment interactions with the potential to maintain genetic variation in immune defence.
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| 7. |
- Ruuskanen, Suvi, et al.
(författare)
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Geographical Variation in Egg Mass and Egg Content in a Passerine Bird
- 2011
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:11, s. e25360-
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Tidskriftsartikel (refereegranskat)abstract
- Reproductive, phenotypic and life-history traits in many animal and plant taxa show geographic variation, indicating spatial variation in selection regimes. Maternal deposition to avian eggs, such as hormones, antibodies and antioxidants, critically affect development of the offspring, with long-lasting effects on the phenotype and fitness. Little is however known about large-scale geographical patterns of variation in maternal deposition to eggs. We studied geographical variation in egg components of a passerine bird, the pied flycatcher (Ficedula hypoleuca), by collecting samples from 16 populations and measuring egg and yolk mass, albumen lysozyme activity, yolk immunoglobulins, yolk androgens and yolk total carotenoids. We found significant variation among populations in most egg components, but ca. 90% of the variation was among individuals within populations. Population however explained 40% of the variation in carotenoid levels. In contrast to our hypothesis, we found geographical trends only in carotenoids, but not in any of the other egg components. Our results thus suggest high within-population variation and leave little scope for local adaptation and genetic differentiation in deposition of different egg components. The role of these maternally-derived resources in evolutionary change should be further investigated.
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| 8. |
- Strand, Tanja, et al.
(författare)
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The MHC class II of the Black grouse (Tetrao tetrix) consists of low numbers of B and Y genes with variable diversity and expression
- 2007
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Ingår i: Immunogenetics. - : Springer Science and Business Media LLC. - 0093-7711 .- 1432-1211. ; 59:9, s. 725-734
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Tidskriftsartikel (refereegranskat)abstract
- We found that the Black grouse (Tetrao tetrix) possess low numbers of Mhc class II B (BLB) and Y (YLB) genes with variable diversity and expression. We have therefore shown, for the first time, that another bird species (in this case, a wild lek-breeding galliform) shares several features of the simple Mhc of the domestic chicken (Gallus gallus). The Black grouse BLB genes showed the same level of polymorphism that has been reported in chicken, and we also found indications of balancing selection in the peptide-binding regions. The YLB genes were less variable than the BLB genes, also in accordance with earlier studies in chicken, although their functional significance still remains obscure. We hypothesize that the YLB genes could have been under purifying selection, just as the mammal Mhc-E gene cluster.
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