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  • 1.
    Björklund, Niklas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Vouti, Jyrki
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    The significance of the eye-combs in male-male signalling and female choice in the black grouse1997Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 2. Forsgren, Elisabet
    et al.
    Reynolds, John D.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Behavioural ecology of reproduction2002In: Handbook of Fish Biology and Fisheries: Vol. 1, Fish biology / [ed] Paul J. B. Hart and John D. Reynolds, Malden: Blackwell Science , 2002, p. 225-250Chapter in book (Other academic)
  • 3.
    Gullberg, Donald
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Tingström, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Thuresson, A C
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical and Physiological Chemistry.
    Olsson, L
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Terracio, L
    Borg, T K
    Rubin, Kristofer
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Beta 1 integrin-mediated collagen gel contraction is stimulated by PDGF1990In: Experimental Cell Research, ISSN 0014-4827, E-ISSN 1090-2422, Vol. 186, no 2, p. 264-272Article in journal (Refereed)
  • 4. Gustafson, Rolf
    et al.
    Jaenson, Thomas G.T.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology. Uppsala University, Music and Museums, Museum of Evolution.
    Gardulf, Ann
    Mejlon, Hans
    Uppsala University, Music and Museums, Museum of Evolution. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Svenungsson, Bo
    Prevalence of Borrelia burgdorferi sensu lato infection in Ixodes ricinus in Sweden1995In: Scandinavian Journal of Infectious Diseases, ISSN 0036-5548, E-ISSN 1651-1980, Vol. 27, no 6, p. 597-601Article in journal (Refereed)
    Abstract [en]

    Between 1988-1991, a total of 3,141 Ixodes ricinus ticks, 2,740 adults and 401 nymphs, was collected from different localities in 23 of the 25 provinces of Sweden. The ticks were identified, dissected and examined for the presence of Borrelia spirochetes. Indirect immunofluorescence was performed, using an antiserum obtained from rabbits, immunized with sonicated, whole Borrelia burgdorferi spirochetes isolated from Swedish Ixodes ricinus ticks. Borrelia-positive I. ricinus were found in all 23 provinces. The prevalence of infection in adults ranged from 3% in Jämtland to 23% in Södermanland. In nymphs, the infection prevalence ranged from 0% in 9 provinces to 15% in Södermanland. A significantly greater proportion of the adult ticks were found to be positive for Borrelia in the southern and central parts of Sweden as compared to the northern part (Norrland). No significant difference in prevalence could be demonstrated between the western and eastern parts of Sweden. On average, 10% of the nymphs and 15% of the adult I. ricinus were positive for Borrelia. Of 41 non-I. ricinus ticks, none was positive for Borrelia. This study shows that Borrelia burgdorferi sensu lato is present throughout the distributional area of I. ricinus in Sweden. This should lead to increased awareness of signs and symptoms compatible with Lyme borreliosis in persons living in or visiting areas where I. ricinus is present.

  • 5.
    Hallböök, Finn
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Genetics and Pathology, Medical Genetics.
    Ebendal, Ted
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Persson, Håkan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Genetics and Pathology, Medical Genetics.
    Production and characterization of biologically active recombinant beta nerve growth factor1988In: Molecular and Cellular Biology, ISSN 0270-7306, E-ISSN 1098-5549, Vol. 8, no 1, p. 452-456Article in journal (Refereed)
    Abstract [en]

    DNA fragments encoding either rat or chicken beta nerve growth factor (NGF) were inserted in the expression vector p91023(B) for transient expression in COS cells. The two NGF constructs produced RNA transcripts and proteins of the predicted sizes. Conditioned media from the transfected cells stimulated neurite outgrowth from cultured chicken embryo sympathetic ganglia. The results show that the rat or chicken NGF gene can direct the synthesis of a biologically active NGF protein after transfection of COS cells.

  • 6.
    Hammar, Johan
    Uppsala University, Department of Zoology.
    Evolutionary ecology of arctic char (Salvelinus alpinus (L.)): Intra- and interspecific interactions in circumpolar populations1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis examines a suite of ecological and genetic mechanisms influencing the fundamental and realized niche borders of European and North American populations of the Arctic char (Salvelinus alpinus (L.)) species complex in allopatry as well as in sympatry with brown trout (Salmo trutta) or brook trout (Salvelinus fontinalis).

    The Arctic char has a circumpolar distribution and is the only freshwater fish taxon in lakes at highlatitudes and at high altitudes in subarctic and alpine regions. Whereas abiotic factors such as extremetemperature constrain the reproduction in the north, biotic factors such as interspecific competition cause the niche of the Arctic char to be compressed in the south.

    ln allopatric populations of Arctic char, phenotypic flexibility, size bimodality and cannibalism were found to be characteristic features and to increase in magnitude with latitude and altitude. Several food niches were found to be exploited by Arctic char. An ontogenetic switch to cannibalism was found to enhance survival, and also reproductive success as older females have larger eggs and are more fecund. Cannibalism may commence at a body sire of about 200 mm. The switch is very fast and is associated with a pause in the reproductive investment, while allocation to somatic growth is maximized. Individual char with a relatively large gape on average had higher condition, were more likely to become cannibalistic and probably achieved a higher reproductive output, since their gonads were on average larger. As a cost of cannibalism, larger char accumulated cestodan parasites, which reduced their survival and were responsible for the termination of the large-sized modal group in the population.

    In sympatry with brown trout in Scandinavia competitive and predatory interactions were found to beimportant. However, a temperature dependent dietary shift during winter allowed an ecological release on the part of the char, the realized niche of which could therefore approach the fundamental niche as determined from allopatric populations. Analogous processes were found to occur in Newfoundland between Arctic char and brook trout, where sympatry in high and low altitude lakes also caused a differential switch in the direction of piscivory. The evolutionary divergence between Arctic char and brook trout in sympatry is probably retarded as a result of hybridization and introgression, which are more frequent at the borders of the distribution of the respective species.

  • 7.
    Hemborg, Christer
    Uppsala University, Department of Zoology.
    Reproduction and moult in pied and collared flycatchers (Ficedula hypoleuca and F. albicollis): A life-history approach1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis examines the trade-offs between investments in reproduction and self-maintenance (moult) in pied and collared flycatchers (Ficedula hypoleuca and F. albicollis). These two long-distance migratory passerine bird species were studied on the breeding grounds in Fennoscandia and in England.

    Passerine birds, such as pied and collared flycatchers, usually start moulting soon after breeding. However, in this study a temporal overlap between reproduction and moult was found in both species. Adult birds with moult-breeding overlap suffered reduced fitness, both in terms of reproductive success and survival probability, indicating trade-offs between reproduction and moult. However, collared flycatchers with experimentally increased reproductive investment initiated their moult at the sametime as those for which the reproductive investment was experimentally reduced. Thus, in this case no trade-off between reproduction and moult was identified.

    In both species, males more often than females showed a moult-breeding overlap. Moreover, female pied flycatchers were found to have a more fixed time-table for reproduction and moult than males. The sexual difference in timing of moult suggests a sexual conflict over allocation of resources for reproduction and moult, respectively. Female pied and collared flycatchers mated to males with moult-breeding overlap had a lower survival probability than females mated to non-moulting males. These females probably had to increase their reproductive investment as a result of their males starting to moult.

    The timing of breeding and moult was compared among three Fennoscandian populations of the pied flycatcher. In all three populations and in both sexes, reproduction and moult overlapped. However, contrary to what has been assumed, this overlap did not become more pronounced with increasing latitude. This suggests that long-distance migrants breeding at high latitudes employ other strategies than moult-breeding overlap to compensate for the short breeding season.

  • 8.
    Jaenson, Thomas G.T.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Virus-like rods associated with salivary gland hyperplasia in tsetse, Glossina pallidipes1978In: Transactions of the Royal Society of Tropical Medicine and Hygiene, ISSN 0035-9203, E-ISSN 1878-3503, Vol. 72, no 3, p. 234-238Article in journal (Refereed)
    Abstract [en]

    Long, virus-like rods were discovered in hyperplastic salivary glands of Glossina pallidipes Austen from Kibwezi Forest (2 ° 27′ S, 37 ° 55′ E), Kenya. The glands were enlarged up to four times the normal diameter. This increase in size was due to a cellular proliferation of the glandular epithelial cells and hypertrophy of their nuclei and cytoplasm. Nuclear and cytoplasmic inclusions were present in the enlarged cells but were not found in cells of normal-sized glands. Electron microscopy revealed many virus-like rods in the abnormal glands. Males with such glands were often completely sterile. Abnormal growth of the ovarioles was a significant feature of young females with hyperplastic glands. Both sexes of wild and laboratory-bred flies were found with enlarged glands. One way of transmission of the trait seems to be from mother to progeny.

  • 9.
    Jones Fur, Cheryl
    Uppsala University, Department of Zoology.
    Ecology, sexual selection and variable mating tactics in fallow deer (Dama dama)1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis investigates ecological and evolutionary mechanisms behind the variation in male mating behaviour in fallow deer (Dama dama) populations. Two Swedish populations of fallow deer were studied, a semi-wild enclosed population on the island of Öland in the Baltic Sea (Ottenby), and a deer farm located north of Uppsala (Bälinge).

    At Ottenby, the most successful mating tactic was defense of small mating territories (stands) where males display through scent marking and groaning. The unstable female groups and small group sizes observed supported the prediction that in such populations, males are likely to defend mating territories. Mating stands were found in areas where canopy cover was greatest, producing natural arenas for olfactory and auditory displays. These stands are not likely to be resource territories as the presence of vegetation favoured by females was not found in association with stand location.

    A strong mating skew was observed in both populations. Among the Ottenby deer, a few of the stand-defending males achieved most of the observed copulations, and high groaning rates were associated with high rates of female access. At Bälinge, where males do not defend mating stands, access to females and mating success were determined through dominance interactions. Dominance rank was found to be positively associated with scent marking, but interestingly, not associated with rates of fighting or aggression. Dominant males at Bälinge and stand-holding males at Ottenby scent marked most frequently early in the rut. In addition, Ottenby males scent marked more in the presence of other males, while females rarely showed an interest in the marks created by males. Scent marking is associated with dominance behaviour and mating territory defence in a number of different cervid species. For fallow deer and other members of the Cervinae, scent marking may also be involved in male-male competition for mates, while among the Odocoilinae, in addition to male-male competition, scent marking may facilitate male-female interactions

  • 10.
    Mejlon, Hans A
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Jaenson, Thomas G.T.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Mather, Thomas N.
    Center for Vector-borne Disease, University of Rhode Island, Kingston.
    Evaluation of host-targeted applications of permethrin for control of Borrelia-infected Ixodes ricinus (Acari: Ixodidae)1995In: Medical and Veterinary Entomology, ISSN 0269-283X, E-ISSN 1365-2915, Vol. 9, no 2, p. 207-210Article in journal (Refereed)
  • 11.
    Mejlon, Hans
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Jaenson, Thomas G.T.
    Uppsala University, Music and Museums, Museum of Evolution.
    Questing behaviour of Ixodes ricinus ticks (Acari: Ixodidae)1997In: Experimental & applied acarology, ISSN 0168-8162, E-ISSN 1572-9702, Vol. 21, no 12, p. 747-754Article in journal (Refereed)
    Abstract [en]

    The vertical distribution in the vegetation of questing Ixodes ricinus ticks was investigated in two different vegetation types ('high' and 'low' vegetation) at two localities in south-central Sweden during 1992-1993 (Torö) and 1995 (Bogesund). Significant correlations were found between the vertical distribution of immature ticks and the height of the vegetation. The greatest mean availabilities of the larvae and nymphs in low vegetation were in the intervals 0-9 and 30-39 cm, respectively. The larval numbers were greatest close to the ground (0-29) in both high and low vegetation. The larval : nymphal ratio, at ground level at localities free of ground vegetation, varied between 8:1 and 32:1. In high vegetation, the greatest mean numbers of nymphal and adult ticks were at height intervals of 50-59 and 60-79 cm, respectively. These ranges are within the estimated height interval (40-100 cm) of the main part of the body surface of their 'preferred' host, the roe deer (Capreolus capreolus). The presence of most questing I. ricinus larvae at ground level would favour the transmission of Borrelia burgdorferi s.l., since this is where the highly reservoir-competent rodents and shrews usually occur.

  • 12.
    Merilaita, Sami
    Uppsala University, Department of Zoology.
    Cryptic coloration, microhabitat choice and polymorphism in Idotea baltica (Isopoda)1999Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis I have studied cryptic coloration, microhabitat use and colour polymorphism in the marine isopod Idotea baltica. In the Baltic Sea it lives and feeds mainly on the seaweed Fucus vesiculosus, which in sheltered sites usually is whitespotted on its lower parts due to epizoites. The white-spotted morph of I. baltica was found to suffer a lower predation risk on white-spotted background and the uniform morph had a lower predation risk on a uniform background. However, the morphs of I. baltica did not prefer visually matching microhabitat. Instead, males more than females used the exposed upper parts of F. vesiculosus. This probably results from males and females differently trading feeding against protection from visual predators, and may explain the differences in morph frequencies between the sexes.

    A comparison of colour pattern elements of the isopods and on the seaweed showed that the white-spotted morph achieves crypsis not only through visual resemblance to its background, but also by concealment of the body outline through disruptive coloration. A model of optimisation of crypsis in heterogeneous habitats suggested that maximal protection can sometimes be achieved by a coloration compromising the requirements of several microhabitats.

    A comparison among ten I. baltica populations inhabiting sites with highly variable densities of white epizoites on F. vesiculosus revealed that variation in morph frequencies was related to the density of epizoites, but not to the small variation in allozyme frequencies. These results suggest that the colour polymorphism in I. baltica is maintained by divergent local selection for crypsis counteracted by gene flow as well as by opposing selection on coloration in males and females.

  • 13.
    Merilä, J
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Gustafsson, L
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Temporal stability and microgeographic homogeneity of heritability estimates in a natural bird population1996In: Journal of Heredity, ISSN 0022-1503, E-ISSN 1465-7333, Vol. 87, no 3, p. 199-204Article in journal (Other academic)
    Abstract [en]

    Temporal and spatial variation in heritability estimates and additive genetic covariances of seven morphological traits were studied over a 9-year period in a natural population of the collared flycatcher, Ficedula albicollis. In spite of significant differences in trait means among young born in different years, we found no evidence for between-years variation in heritability estimates in any of the traits. Likewise, the elements of genetic covariance matrices were significantly correlated among the different study years, and the null hypothesis of no similarity was rejected. Furthermore, despite significant differences in mean tarsus length of birds born in different nestbox areas (habitats), we found no evidence for differences in heritability of tarsus length in different habitats. Our results indicate that the assumption on the constancy of quantitative genetic parameters over time and environments in evolutionary models may hold at least over short temporal or spatial distances.

  • 14.
    Merilä, Juha
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Björklund, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Population divergence and morphometric integration in the greenfinch (Carduelis chloris): evolution against the trajectory of least resistance?1999In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 12, no 1, p. 103-112Article in journal (Refereed)
    Abstract [en]

    Theory predicts that genetic and phenotypic correlations among traits may direct the process of short-term evolution by limiting the directions of variation available to natural selection to act on. We studied correlations between 14 skeletal traits in 10 geographically distinct and relatively young greenfinch (Carduelis chloris) populations to unravel whether the divergence among populations has occurred into directions predicted by the within-population correlations (cf. drift/correlated responses models), or whether it is better explained by ‘adaptive’ models, which predict no necessary association between within- and among-population correlations (allometries). We found that the within-population character correlations (or covariances) did not predict character divergence between populations. This was because the first eigenvector of the among-population correlation/covariance matrix, summarizing the major dimension of divergence, was a bipolar body:beak dimension, and distinct from the (≈ isometric) first eigenvector of within-population matrix. Hence, as the divergence among greenfinch populations cannot be satisfactorily accommodated by drift/correlated response models, an adaptive basis for divergence is suggested. The second major axis of within-population variation was a classical ‘group size’ factor revealing that beak size was more or less free to vary independently of body size. Consequently, even if the divergence among populations cannot be simply accommodated to expectations of drift and correlated response models, it is striking that the most pronounced size-independent (nonallometric) changes had occurred along the second largest dimension of variance. This could mean that selection pressures which shape integration within populations are the same as those that cause divergence among populations. A relaxed beak:body integration could also occur as a result of species level selection favouring taxa in which independent evolution of beak and body is made possible.

  • 15.
    Merilä, Juha
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Björklund, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Baker, AJ
    Genetic population structure and gradual northward decline of genetic variability in the greenfinch (Carduelis chloris)1996In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 50, no 6, p. 2548-2557Article in journal (Other academic)
  • 16.
    Merilä, Juha
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Björklund, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Baker, AJ
    The successful founder: Genetics of introduced Carduelis chloris (greenfinch) populations in New Zealand1996In: Heredity, ISSN 0018-067X, E-ISSN 1365-2540, Vol. 77, p. 410-422Article in journal (Refereed)
    Abstract [en]

    The amount and distribution of genetic variation in seven introduced New Zealand populations of Carduelis chloris were assessed at 40 loci using starch gel electrophoresis and compared with those in native European populations. Fewer alleles (1.45) and fewer polymorphic loci (33 per cent) were detected across the introduced populations than across native populations (1.75, 55 per cent), reflecting the narrow geographical origin of the introduced populations. There was no evidence for severe inbreeding or genetic drift as the levels of average heterozygosity (H = 0.025), percentage polymorphic loci (P = 16.9) and average number of alleles per locus (A = 1.22) were indistinguishable from levels observed within European populations (77 = 0.025, P =14.1, A = 1.19). Furthermore, introduced populations were genetically less weakly differentiated (FST = 0.022) than native populations (FST = 0.041), indicating that little genetic drift has been involved in the colonization of the new range. Similar levels of genetic variability in native and introduced greenfinch populations are consistent with theoretical expectations as the founder population size was relatively large (>60 individuals) and a rapid increase in population size directly after colonization was documented. A review of earlier studies on introduced birds also revealed that reductions in levels of genetic variability seem to be inversely proportional to the size of the founder population, and that less variation has been lost if the rate of population growth directly after introduction was fast.

  • 17. Merilä, Juha
    et al.
    Fry, James D.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Genetic variation and causes of genotype-environment interaction in the body size of blue tit (Parus caeruleus)1998In: Genetics, ISSN 0016-6731, E-ISSN 1943-2631, Vol. 148, no 3, p. 1233-1244Article in journal (Other academic)
    Abstract [en]

    In several studies of natural populations of birds, the heritability of body size estimated by parent-offspring regression has been lower when offspring have developed in poor feeding regimens than when they developed in good feeding regimens. This has led to the suggestion that adaptation under poor regimens may be constrained by lack of genetic variation. We examined the influence of environmental conditions on expression of genetic variation in body size of nestling blue tits (Parus caeruleus) by raising full sibs in artificially reduced and enlarged broods, corresponding to good and poor feeding regimens, respectively. Individuals grown in the poor regimen attained smaller body size than their sibs grown in the good regimen. However, there was among-family variation in response to the treatments--i.e., genotype-environment interactions (GEIs). Partitioning the GEI variance into contributions attributable to (1) differences in the among-family genetic variance between the treatments and (2) imperfect correlation of genotypic values across treatments identified the latter as the main cause of the GEI. Parent-offspring regressions were not significantly different when offspring were reared in the good environment (h2 = 0.75) vs. when they were reared in the poor environment (h2 = 0.63). Thus, there was little evidence that genetic variance in body size was lower under the poor conditions than under the good conditions. These results do not support the view that the genetic potential for adaptation to poor feeding conditions is less than that for adaptation to good conditions, but they do suggest that different genotypes may be favored under the different conditions.

  • 18.
    Merilä, Juha
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Przybylo, Robert
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Sheldon, Ben C.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Genetic variation and natural selection on blue tit body condition in different environments1999In: Genetical Research, ISSN 0016-6723, E-ISSN 1469-5073, Vol. 73, no 2, p. 165-176Article in journal (Other academic)
    Abstract [en]

    An increasing amount of evidence indicates that different forms of environmental stress influence the expression of genetic variance in quantitative traits and, consequently, their evolvability. We investigated the causal components of phenotypic variance and natural selection on the body condition index (a trait often related to fitness in wild bird populations) of blue tit (Parus caeruleus) nestlings under contrasting environmental conditions. In three different study years, nestlings grown under a poor feeding regime attained lower body condition than their full-sibs grown under a good feeding regime. Genetic influences on condition were large and significant in both feeding regimes, and in all three study years. However, although estimates of additive genetic variance were consistently higher in the poor than in the good environment, heritability estimates for body condition index were very similar in both environments due to higher levels of environmental variance in the poor environment. Evidence for weak genotype×environment interactions was obtained, but these contributed little to variance in nestling condition. Directional natural selection on fledging condition of nestlings was detected, and there were no indications of year or environmental effects on the form and intensity of selection observed, in a sample of 3659 nestlings over four years. However, selection on fledging condition was very weak (standardized selection gradient, β=0·027±0·016 SE), suggesting that, in the current population, the large additive genetic component to fledging condition is not particularly surprising. The results of these analyses are contrasted with those obtained for other populations and species with similar life-histories.

  • 19. Merilä, Juha
    et al.
    Sheldon, Ben C.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Testis size variation in the greenfinch Carduelis chloris: relevance for some recent models of sexual selection1999In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 45, no 2, p. 115-123Article in journal (Refereed)
    Abstract [en]

    Interspecific evidence that testis size responds to selection caused by sperm competition has been obtained from many taxa. However, little is known about the sources of intraspecific variation in testis size, although such variation may have functional significance. Variation in testis size and asymmetry was studied within and between eight geographically separated (and genetically differentiated) populations of greenfinches Carduelis chloris. The relationships between testis size and plumage brightness (degree of yellowness) and the prevalence of haematozoan infections were also investigated in three of these populations, as they related to the predictions of the immunocompetence handicap hypothesis, and Møller's hypothesis relating directional testis asymmetry to phenotypic quality. There were large differences between populations in testis size, with males from northern populations having larger testes than those from southern populations. Within populations, large testes were associated with larger body size and greater age. When the influence of these factors was removed statistically, males with large testes were more likely to be infected with haematozoan parasites, and had brighter yellow plumage. No evidence was found that directional asymmetry in testis size was related to either of these measures of phenotypic quality. These results are consistent with the hypothesis that males with large testes, while signalling higher phenotypic quality as revealed by increased plumage brightness, also pay a cost in terms of reduced immunocompetence, revealed by the increased probability of infection in these males. That these patterns were similar in three different populations adds further strength to these conclusions. Our results suggest that studying the sources of variation in testis size among individuals can reveal interesting processes in sexual selection.

  • 20.
    Nordling, Dag
    Uppsala University, Department of Zoology.
    Trade-offs between life history traits and immune defence in the collared flycatcher Ficedula albicollis1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis examines the effects of reproductive effort on immune function and parasite resistance in breeding collared flycatchers, Ficedula albicollis. It also focuses on the role of the immune function in the trade-off between number and fitness of offspring.

    The reproductive effort of collared flycatchers was altered by manipulating the number of offspring in their broods. Increased effort affected negatively immune function and parasite resistance. The total immunoglobulin and leukocyte levels decreased, as did the specific immune responses to Newcastle disease virus vaccine, whereas the intensity of Haemoproteus infections increased. Increased effort reduced the probability of survival. Recapture of females subjected to experimental manipulation the previous year showed that increased effort had long-term negative effects on reproduction and parasite resistance. Prevalence of haematozoan infections increased, breeding onset was delayed and clutch size reduced. The data suggest a trade-off between investment in reproduction and immune defence, and increased susceptibility to infectious disease via immune suppression as a pathway for the life-history cost of reproduction.

    During the mating/oviposition period, females had more than twice as high prevalence of Trypanosoma infections compared to males, whereas males tended to be more frequently infected by Haemoproteus. During the subsequent nestling feeding period, the total haematozoan prevalence was male-biased. Leukocyte and erythrocyte levels were also sexually dimorphic. It is suggested that, as a result of differential selection pressures during reproduction, males and females have different strategies for allocating resources to immune defence and reproductive effort.

    Nestling immunocompetence was assessed by measuring the ability to degrade/remove a subcutaneously applied immunogen. Two acute phase proteins were quantified as a means to assess the effect of experimental brood size on the susceptibility to natural infections. Poor immunocompetence and increased levels of acute phase proteins were associated with low body mass and reduced survival. Increased brood size affected nestling growth rate negatively and reduced their immunocompetence. However, no detectable effects on infection susceptibility were observed. Three explanations are suggested: i) negligible effects of reduced immunocompetence, ii) protection by maternally acquired antibodies, iii) adaptive reaction norms. Under poor rearing conditions, offspring may be prepared to cut down on an already poor growth process to secure immune function and thereby survival.

  • 21.
    Przybylo, Robert
    Uppsala University, Department of Zoology.
    Causes and consequences of quantitative trait variation for reproductive performance in hole nesting birds1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis examines the causes and consequences of environmental variability and individual morphological differences on breeding success and survival in three hole nesting birds.

    An analysis of directional and stabilising natural selection in Collared Flycatchers (Ficedula albicollis) suggested that forces of selection acting on quantitative traits are weak and cannot explain the observed sexual size dimorphism (SSD) in this species. The hypothesis that food niche differentiation might enhance reproductive success and explain the evolution of SSD was not supported by studies of Great and Blue Tits (Parus major and P. caeruleus). Analysis of natural selection on nestling body condition in Blue Tits revealed weak positive directional selection on this trait. This observation is consistent with the moderate heritability (h2 = 0.4) of body condition uncovered by a quantitative genetic analyses.

    Territorial quality had a greater effect on breeding success than parental quality in Blue Tits. Nevertheless male, but not female quality, affected offspring condition. Climatic fluctuations were found to affect laying date and male tarsus length in Collared Flycatchers. The effects of individual-specific features were found to be more important than environmental factors in determining laying date and variation in morphological traits in this species. The high degree of concordance between cross-sectional and longitudinal analyses of the effect of environmental factor on laying date suggests the observed response can be explained entirely in terms of phenotypic plasticity.

  • 22.
    Pålsson, Katinka
    Uppsala University, Department of Zoology.
    Ecology and control of Anopheles mosquitoes and human malaria in Guinea Bissau, West Africa1999Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis analyses the relationship between risk of exposure to infective Anophelesmosquitoes and different environmental factors, in particular house construction, presence ofdomestic animals and house location, in coastal Guinea Bissau, West Africa. The potentialeffect of permethrin-impregnated bed nets on mosquito abundance in bed rooms, and on thePlasmodium parasite prevalence in children was also analysed. In addition, measures frequentlyused traditionally against mosquitoes in the Oio region of Guinea Bissau were identified andexperimentally evaluated.

    The house construction, in particular presence of open eaves, and presence of animals (pigs)in the house and a well in the garden were factors associated with increased mosquitoabundance indoors.

    Permethrin-impregnated bed nets dramatically reduced mosquito abundance indoors. Also,the malaria (Plasmodium) parasite prevalence was significantly lower in children sleepingunder impregnated bed nets compared to that of children sleeping under unimpregnated bednets.

    The most commonly used natural mosquito repellents were based on the plants Hyptissuaveolens and Daniellia oliveri. Experiments, both indoors and outdoors, revealed that these and certain other plants traditionally used in Guinea Bissau possess significant mosquito repellent properties. Increased knowledge about traditionally used mosquito repellents may reveal that certain of these plant-derived products may have particular advantages over imported synthetic arthropod repellents and chemical pesticides.

  • 23.
    Qvarnström, Anna
    Uppsala University, Department of Zoology.
    Sexual selection in the collared flycatcher (Ficedula albicollis): A life-history perspective1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis integrates sexual selection theory with life history theory to elucidate the causes and consequences of variation in a male secondary sexual trait. The model organism, the collared flycatcher (Ficedula albicollis), was studied on Gotland, Sweden.

    Male collared flycatchers possess a conspicuous white forehead patch that was shown to function as an honest signal of fighting ability in contests over nest sites (a necessary resource to attract females), where males with relatively large patch size enjoyed a competitive advantage. Forehead patch size wasfound to be a heritable condition-dependent trait affected by a male's natal environment and by genotype-environment interactions, As revealed by experimental manipulations males traded their investment of resources in competition over mates (indicated by patch size) against their investment in parental care and vice versa.

    Although forehead patch size could not be used as a cue of male parental ability by mate-choosing females, there was a positive relationship between male patch size and female fecundity but only among late breeding birds. This probably was a result of quality differences between territories becoming moreimportant as general rearing conditions declined over the season.

    Average life span was highest among males with intermediate forehead patch size suggesting that large-patched males sacrificed not only their parental ability but also their own future survival chances for a current mating advantage.

    Consequently, my results suggest that both sexual selection theory and life history theory would benefit from an increased integration.

  • 24.
    Stenström, David
    Uppsala University, Department of Zoology.
    Mating behaviour and sexual selection in non-lekking fallow deer (Dama dama)1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis examines both behavioural and morphological traits influencing male mating success in non-lekking fallow deer (Dama dama). The thesis contains results based on behavioural observations and experimental studies made on Öland and around Uppsala, Sweden.

    In an initial observational study I found evidence that scent marking may be involved in male competition. While scent marking is an almost universally occurring phenomenon among mammals, the exact function of the scent marks is poorly understood. In an experimental study I found evidence supporting the hypothesis of scent marks being used by fallow deer males for status advertisement. If challenged, males were found to increase scent marking, and males with high rates of scent marking were subjected to fewer agonistic encounters than those with low scent marking rates. In addition I found a positive correlation between scent marking during the early stages of the rut and mating success during the peak of the rut, indicating a possible fitness benefit of scent marking to the males in terms of increased mating success.

    The optimality argument that first reproduction occurs at the age when the benefits of reproduction outweigh the costs implies that if conditions change, age at first reproduction should also change. In an experimental study in which we examined the response of different aged males to changes in the level of competition, evidence was found supporting this hypothesis. Our results suggest that male social dominance is the most important determinant of the level of participation in the rut for male fallow deer.

    A negative relationship between trait size and fluctuating asymmetry has been proposed as indicative of trait size being an honest signal of male quality. Using an extensive literature data set I found this relationships to be negative in two species, and positive or flat in two species. Thus, quality signalling through size and fluctuating asymmetry in antlers does not seem to be a ubiquitous mechanism in deer species.

  • 25.
    Svensson, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Reproductive Costs in two Sex-Role Reversed Pipefish Species (Syngnathidae)1988In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 57, no 3, p. 929-942Article in journal (Refereed)
    Abstract [en]

    (1) In two species of pipefish (Syngnathidae) the reproductive costs of the two sexes were compared to see how they might influence patterns of sex-role reversal. (2) In Syngnathus typhle, males brood their offspring in a brood pouch, providing them with nutrients and oxygen. Sexes are monomorphic. Males faced reproductive costs in terms of a lower food intake compared with females. Also, males grew more slowly than females, which yields a cost to future reproduction, as larger males could brood more offspring. No sexual difference in predation risk was found. The over-winter survival of males was probably lowered because intestinal fat deposition was delayed as a result of their reproductive efforts. (3) In Nerophis ophidion, males brood their offspring attached to their ventral body side, and provide them with nutrients and oxygen. Sexes are dimorphic, females being larger and brighter in colour. Males suffered an increased predation risk when brooding. No indications of energetic costs were found, e.g. through a lowered food intake or a slower growth rate. (4) Reproductive costs differed in the two species, probably reflecting differences in brood care. However, in both species the limiting sex, males, faced higher reproductive costs than females, as would be expected in sex-role reversed animals.

  • 26. Tälleklint, Lars
    et al.
    Jaenson, Thomas G.T.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Mejlon, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Transmission of the Lyme borreliosis spirochete at the mammal reservoir: tick vector interface in Sweden1995In: Proceedings of the 2:nd International Conference on tick-borne pathogens at the host-vector interface: a global perspective, 1995Conference paper (Other academic)
    Abstract [en]

    During 1988 to 1995 we examined the density of questing Ixodes ricinus nymphs infected with Borrelia burgdorferi s.l. at 12 areas in southern and southcentral Sweden. There were great differences in the density of questing Borrelia-infected I. ricinus nymphs between these areas, i.e., from <10 to >500 infected nymphs per hectare. The density of I. ricinus nymphs had a greater impact on this variation than the prevalence of Borrelia-infection in the nymphs, suggesting that reservoir incompetent cervids, which are important hosts for adult female I. ricinus, indirectly increase the risk of encountering Borrerlia-infected nymphal ticks despite the ability of cervids to divert larval ticks from reservoir competent mammals. There was a strong correlation between the mean number of Borrelia-infected nymphs per hectare and the mean number of nymphs per hectare, suggesting that it may be possible to assess the risk of encountering Borrelia-infected ticks in different areas without examining the prevalence of spirochetal infection.

  • 27.
    Vincent, Amanda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Operational sex ratios and behavioral sex differences in a pipefish population1994In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 34, p. 435-442Article in journal (Refereed)
    Abstract [en]

    In the pipefish Syngnathus typhle, only males brood embryos in specially developed brood pouches, supplying oxygen and nutrients. Laboratory studies have shown that this elaborate paternal care has led to sex-role reversal in this species: males limit female reproductive rate, females are the primary competitors for mates and males exercise greater selectivity in accepting mates. In the first field study of this pipefish, we describe mating behaviour in the wild and test the hypothesis that temporal variations in the operational sex ratio (OSR) determine sex differences in mating behaviour. Our study comprised two reproductive seasons of two sequential mating periods each, the latter separated by a lengthy interval of male brooding. During mating periods, females displayed to all males without wandering and males moved about searching for females, without reacting to all females. The OSR was least female-biased (or even male-biased) at the onset of the breeding season, when most pipefish were simultaneously available to mate, but became strikingly female-biased as males' pouches were filled. The OSR remained substantially female-biased during the second mating period, because few males became available to remate at any one time. As hypothesised, female-biased OSRs resulted in more female-female meetings. As well, females were above the eelgrass more often than brooding males, thus exposing themselves to conspecifics and/or predators. In the second year, males arrived earlier than females on the breeding site and male pregnancies were shorter, because of higher water temperatures, so rematings occurred earlier. Males met more often during that year than the previous one, but male competitive interactions were still not observed. The field results support laboratory studies and demonstrate that behaviours associated with female-female competition are more prominent when the OSR is more female-biased.

  • 28.
    Wikars, Lars-Ove
    Uppsala University, Department of Zoology.
    Effects of forest fire and the ecology of fire-adapted insects1997Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Fire is widely recognised for its major impact on boreal forest ecosystems. The altereddisturbance regime due to effective fire suppression and extensive forestry may be a majorthreat to biodiversity.

    If logging preceded burning, the pyrophilous (Gr. fire-loving) beetle Sericoda quadripunctata failed to reproduce. Because fires had a moderate impact on survival of ground- andwood-living beetles, pyrophilous species arriving at burned clear-cuts may face competitionfrom a fauna already adapted to open habitat conditions.

    Burning affected species composition through both habitat and substrate change.Comparing fire-scorched and unburned logs in a burned area, and unburned logs at a clear-cutand in a forest, revealed that: 1) fewer phloem-feeding and more ascomycete-feedingarthropods emerged from fire-scorched spruce and birch logs; 2) species richness of beetleswas unaffected by burning; 3) diversity was highest in the burned area; and, 4) host-treespecificity was lower in more disturbed sites and in burned logs.

    The mycangia of the beetle Henoticus serratus contained Trichoderma, an ascomycetegenus suggested to be an important food source for many pyrophilous insects. These insectscan be divided into two groups: mycophagous species that need burned substrate per sebecause ascomycete fungi am favoured, and phloem-feeders and predators that needcompetitive release.

    The need to find forest fires over large geographical and temporal distances may posestrong selection on these species. The pyrophilous beetle Melanophila acuminata had lowerwing load and greater flight-muscle mass than two closely related nonpyrophilous species.This increased allocation to dispersal coincided with fewer eggs and ovarioles, despite alarger body size. This suggests a trade-off between dispersal and fecundity. Adult M.acuminata also emerged over a greater time span within and between years than closelyrelated species, and records made in the field were more extended over the season. Asimulation test, where records were compared with the seasonal distribution of natural firesrevealed that M acuminata does not maximise, but rather optimises, its chance to find fires.

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