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Parasites are expected to exert long-term costs on host fecundity and longevity. Understanding the consequences of heritable polymorphic variation in disease defence in wild populations is essential in order to predict evolutionary... more
Parasites are expected to exert long-term costs on host fecundity and longevity. Understanding the consequences of heritable polymorphic variation in disease defence in wild populations is essential in order to predict evolutionary responses to changes in disease risk. Telomeres have been found to shorten faster in malaria-diseased individuals compared with healthy ones with negative effects on longevity and thereby fitness. Here, we study the impact of haemosporidian blood parasites on telomere dynamics in tawny owls, which display a highly heritable plumage colour polymorphism. Previously, it has been shown that blood parasites have morph-specific impact on body mass maintenance. Here, we show that telomeres shortened faster in individuals with shorter breeding lifespan. Telomere length was negatively associated with the degree of pheomelanic brown coloration and shorter in infected than uninfected individuals. The rate of telomere shortening between breeding seasons was faster in...
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Life-history theory states that although natural selection would favour a maximisation of both reproductive output and life-span, such a combination can not be achieved in any living organism. According to life-history theory the reason... more
Life-history theory states that although natural selection would favour a maximisation of both reproductive output and life-span, such a combination can not be achieved in any living organism. According to life-history theory the reason for the fact that not all traits can be maximised simultaneously is that different traits compete with each other for resources. These relationships between traits that constrain the simultaneous evolution of two or more traits are called trade-offs. Therefore, during different life-stages an individual needs to optimise its allocation of resources to life-history components such as growth, reproduction and survival. Resource limitation acts on these traits and therefore investment in one trait, e.g. reproduction, reduces the resources available for investment in another trait, e.g. residual reproduction or survival. In this thesis I study how food resources during different stages of the breeding event affect reproductive decisions in the Ural owl (...
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2010: Ural owl predation on field voles and bank voles by size, sex and reproductive state. — Ann. Zool. Fennici 47: 90–98. Predation on selected individuals from a population may have consequences for the prey population. We studied... more
2010: Ural owl predation on field voles and bank voles by size, sex and reproductive state. — Ann. Zool. Fennici 47: 90–98. Predation on selected individuals from a population may have consequences for the prey population. We studied predation of breeding Ural owls (Strix uralensis) in south-ern Finland on their two main prey species, field voles (Microtus agrestis) and bank voles (Myodes glareolus), which fluctuate in abundance between years. We identi-fied sex, body mass and reproductive state of the voles in Ural owl nests and of voles caught by snap-trapping in the study area. Our results showed that Ural owls preyed proportionally more upon reproductively active field voles than expected, whereas no such bias was found for predation on bank voles. There was no difference in sex ratio between preyed upon and trapped field voles or bank voles. Ural owls captured heavier individuals of both field voles and bank voles than expected, and in field voles, but not bank voles, reproduct...
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Tawny owl reproduction and offspring sex ratios have been considered to depend on the abundance of small voles. We studied reproductive performance (laying date, clutch and brood size) during 1995–2003 and offspring sex ratios from 1999... more
Tawny owl reproduction and offspring sex ratios have been considered to depend on the abundance of small voles. We studied reproductive performance (laying date, clutch and brood size) during 1995–2003 and offspring sex ratios from 1999 to 2003 in relation to the abundance of small voles and food delivered to the nest in a tawny owl population in southern Finland. Abundance of small voles (field and bank voles) was based on trappings in the field, and estimates of food delivery was based on diet analysis of food remains in the nest boxes. In this population, reproductive output was not related to the abundance of small voles. Analysis of food delivered to the nest showed that the prey weight per offspring varied more than twofold between years and revealed that this difference was mainly related to the proportion of water voles in the diet. Only the number of water voles correlated with laying dates. Offspring sex ratios were weakly male biased (55%) but did not differ from parity. ...
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Research Interests: Information Systems, Zoology, Ecology, Survival Analysis, Ibis, and 4 moreOwls, Voles, Snow Cover, and Field Voles
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Summary 1. Maternal effects have been suggested to function as a mechanism for transgenerational plasticity, in which the environment experienced by the mother is translated into the phenotype of the off- spring. In birds and other... more
Summary 1. Maternal effects have been suggested to function as a mechanism for transgenerational plasticity, in which the environment experienced by the mother is translated into the phenotype of the off- spring. In birds and other oviparous vertebrates where early development is within the egg, mothers may be able to improve the viability prospects of their offspring at hatching by