Obligate brood parasites rely solely on other species, the hosts, to incubate their eggs and raise their offspring, which often reduces the host’s reproductive output. This reproductive cost has led to the evolution of anti-parasite adaptations among hosts, which in turn, has led to better trickery by parasites, a process termed an evolutionary arms race. The objective of this thesis was to investigate host-parasite coevolutionary arms races to address questions of host-use diversity. Host diversity varies dramatically among brood-parasitic species, but reasons for variations in host-use among brood parasites are not well understood. In Chapter 2, I address questions on host diversity specifically, whereas I address questions about coevolutionary interaction between hosts and parasites in Chapters 3, 4 and 5 using two host-parasite systems, one in New Zealand and one in North America. Chapter 2 investigates if host diversity is constrained by aggressive nest defence behaviour. I compared the nest defence behaviour of the exclusive host of the shining cuckoo Chrysococcyx lucidus lucidus on the main islands of New Zealand, the grey warbler Gerygone igata, to two other potentially suitable hosts that are not currently parasitised, the fantail Rhipidura fuliginosa and the silvereye Zosterops lateralis. The results suggest that grey warblers are as aggressive as fantails and silvereyes towards shining cuckoos at the nest and thus, host specialisation in shining cuckoos in New Zealand, at least, does not appear to be the result of nest-defence constraints imposed by potential but unused host species. Chapter 3 investigates if red-winged blackbirds Agelaius phoeniceus, a species that typically accepts the eggs of parasites, recognises, as indicated by changes in incubation behaviour, when they have been parasitised by brown-headed cowbirds Molothrus ater. Recognition without rejection suggests that rejection may be context-dependent but the results suggest that red-winged blackbirds do not recognise when their nests have been parasitised by brown-headed cowbirds, at least at the egg stage. This study was the first to investigate if hosts that almost invariably accept the eggs of parasites recognise when they have been parasitised. Chapter 4 investigated the possibility of coevolutionary arms races occurring through olfactory channels in contrast to earlier work that focussed only on visual and auditory cues. Recent research has revealed that olfactory abilities in birds are more common than previously thought. Uropygial gland secretions are posited to be a key source of avian body odour and its composition has been found to vary among species and individuals as well as between the sexes. I compared gas-chromatography (GC-FID) traces of shining cuckoo preen wax to the GC-FID traces of the grey warbler, the only host of the shining cuckoo in mainland New Zealand, as well as the preen wax of seven other species for evidence of mimicry. Preliminary results suggest there is evidence for mimicry and the potential for odour-based nestling discrimination in grey warblers. Further tests recording the response of grey warblers to odour-manipulated nestlings are necessary. Finally, in Chapter 5, I investigated the response of the song thrush Turdus philomelos, a species that rejects the eggs of the common cuckoo Cuculus canorus and conspecifics at intermediate and low frequencies, respectively, to nest-odour manipulations using the preen wax of conspecifics and heterospecifics. The results suggest song thrush do not use odour to assess the risk of parasitism at least as indicated in terms of changes in incubation behaviour. Investigations of the role of olfaction in avian brood parasite systems can provide a better understanding of brood-parasite coevolution. Only by considering all channels of communication can we be sure to completely understand the coevolutionary dynamics between brood parasites and their hosts.

Olfactory function is affected by demographic, cognitive, and genetic factors. In the present thesis, three empirical studies investigated individual differences in olfactory ability. Study I explored demographic and cognitive correlates in common olfactory tasks; odor detection, odor discrimination, and odor identification. The results indicated that old age influenced performance negatively in all tasks, and that semantic memory proficiency and executive functioning were related to odor discrimination and odor identification performance. No cognitive influence was observed for measurements of olfactory threshold. Using population-based data, Study II investigated a potential influence of the ApoE gene on olfactory identification after controlling for health status, semantic memory, and preclinical and clinical dementia. The main finding was that the ApoE- ɛ4 allele interacted with age, such that older ɛ4-carriers had an impaired odor identification performance relative to older non-carriers. Importantly, the negative ApoE- ɛ4 effect on olfactory proficiency was independent of clinical dementia conversion within five years. Study III investigated the effects of the BDNF val66met polymorphism on olfactory change over a five-year interval, in a community dwelling sample of young and old age cohorts. The results showed that age-related decline in olfactory identification was influenced by the BDNF val66met. In middle-aged subjects, no effect of BDNF val66met was observed although older val homozygote carriers showed a selectively larger olfactory decline than the older met carriers. Overall, results suggest that the relative influence of demographic and cognitive factors vary across different olfactory tasks and that two genes (ApoE and BDNF) impact age-related deficits in odor identification. Potential theoretical and practical implications of the findings are discussed as well as potential limitations of association studies in genomics research.

Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniv. / Härtill 5 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 5 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2005. / Härtill 6 uppsatser.

Thesis (Ph.D. in Neuroscience) -- University of Colorado at Denver and Health Sciences Center, 2005. / Typescript. Includes bibliographical references (leaves 145-171).

Episodic memory for olfactory information is still relatively uncharted. The overall purpose of this thesis is to investigate the sensory and cognitive causes of the well-established age-related decline in olfactory episodic odor memory and of the age-independent sex difference in olfactory episodic memory. The purpose of Study I was to investigate the causes of the sex difference in olfactory episodic memory. The results show that the female advantage in episodic recognition memory seems to be explained by women´s higher aptitude in odor identification for familiar odors. With this background, the purpose of Study II was to investigate the age-related decline in olfactory episodic memory, with a particular eye to the role of odor identification. When controlling for the sensory variables olfactory threshold and odor quality discrimination, and the cognitive factor mental speed, the age-related deterioration in odor identification was eliminated. This suggests that changes in basic sensory and cognitive abilities underlie the age-related impairment in odor identification. The purpose of Study III was to investigate the role of recollective experience and intention to memorize for age-related and sex-related differences in episodic odor memory. Younger adults reported more experiences of remembering, and the elderly adults more experiences of feeling of knowing. The participants benefited from intentionality at encoding when the odors were unfamiliar, but intentionality did not affect memory for the familiar odors. The purpose of Study IV was to investigate the role of subjectively perceived qualities of the encoded odors for episodic memory across age and sex. Odors perceived as unpleasant, intense, and irritable were more easily remembered throughout the adult life span. The oldest adults selectively recognized the odors they rated as highly irritable indicating compensatory use of trigeminal activation. Overall, the result suggests that episodic odor memory rely heavily on both sensory and cognitive abilities, but in a different manner depending on demographic factors. The age-related decline appears to be driven by a sensory flattening disabling adequate cognitive processing. The age-independent sex difference on the other hand, is mainly cognitively mediated and driven by cognitive factors such as the ability to verbalize olfactory information.

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Meerkats are known to strongly rely on chemical communication in social contexts. However, little is known about their use of the sense of smell in food detection and selection. The aim of the present study was therefore to assess whether meerkats are able to (1) detect hidden food using olfactory cues, (2) distinguish the odour of real food from a single food odour component, and (3) build an association between the odour of real food and a novel odour. I employed the buried food test, widely used with rodents to assess basic olfactory abilities, designed to take advantage of the propensity of meerkats to dig. I found that the meerkats were clearly able to find all four food types tested (mouse, chicken, mealworm, banana) using olfactory cues alone and that they successfully discriminated between the odour of real food and a food odour component. In both tasks, the animals dug in the food-bearing corner of the test arena as the first one significantly more often than in the other three corners, suggesting development of an efficient foraging strategy. No significant association-building between a food odour and a novel odour was found within the 60 trials performed per animal. I conclude that meerkats are able to use olfactory cues when foraging and that their sense of smell is well-adapted for recognizing specific odours of behavioural relevance. To the best of my knowledge, this is the first study to successfully employ the buried food test with a carnivore species.

It was previously proposed that expression of secondary sexual characteristics may provide cues to individual's immunocompetence. Body odour could partly serve as one of such characteristics, which provides crucial information about potentional partner even in humans. The main aim of the diploma thesis was to test a relationship between body odour quality and reactivity of immune system. In empirical part of the study we collected body odour samples from 21 men aged between 18-40 years before and two weeks after the vaccination against hepatitis A and B (Twinrix) and meningococcus (Menveo). The participant's blood samples were obtained three times to determine levels of IgG and IgM antibodies (markers of reactivity of immune system), testosterone, cortisol and CRP levels. In the second part of the study, a panel of 88 female raters aged 18-40 assessed body odour samples for their attractiveness, intensity and healthiness. In contrast to our expectations, we found no significant association between levels of antibodies induced by vaccination and perceived body odour attractiveness and health. Simultaneously, there were no significant changes in body odour ratings, neither in levels of testosterone and cortisol ratings, before and after the vaccination. However, we found a negative association...