uu.seUppsala University Publications
Change search
Refine search result
1 - 10 of 10
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the 'Create feeds' function.
  • 1.
    Björklund, Mats
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Merilä, Juha
    Bennet, GF
    Geographic and individual variation on haematozoan infections in the greenfinch, Carduelis chloris1995In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 73, p. 1798-1804Article in journal (Refereed)
  • 2.
    Eklöv, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Halvarsson, Charlotta
    The trade-off between foraging activity and predation risk for Rana temporaria in different food environments2000In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 78, no 5, p. 734-739Article in journal (Refereed)
    Abstract [en]

     

    We evaluated the trade-off between foraging activity and predation risk for larvae of an anuran species presented with different types of food resources. In the laboratory we examined the effects of benthic and phytoplankton resources and the two types combined on the activity and mortality of larvae of the common frog, Rana temporaria, exposed to predatory larva, Dytiscus marginalis.

    Predation mortality of tadpoles increased with the duration of the experiment and was highest in the presence of the phytoplankton resource alone. This was explained by a decrease in prey activity in the benthic- and combined-resource treatments when the predator was present, whereas in the phytoplankton treatment, the activity of the tadpoles were similar in the presence or absence of the predator.

    In the presence of the predator, prey mainly used the bottom of the aquarium in the benthic- and combined-resource treatments. In contrast, in the phytoplankton treatment they used the water column more than in the other treatments. In the presence of the predator, the prey had a lower consumption rate in the phytoplankton treatment than in the other treatments.

    Predator activity did not change among treatments. The results suggest that the trade-off between foraging activity and predation mortality for anuran larvae is strongly affected by the types of food resources present in the environment.

     

     

  • 3. Givskov Sørensen, Jesper
    et al.
    Loeschcke, Volker
    Merilä, Juha
    Laurila, Anssi
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Population and Conservation Biology.
    Effects of predator exposure on Hsp70 expression and survival in tadpoles of the Common Frog (Rana temporaria)2011In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 89, no 12, p. 1249-1255Article in journal (Refereed)
    Abstract [en]

    Predator-induced changes in prey behavior and morphology are widespread, but little is known about physiological and cellular-level responses in prey in response to predation risk. We investigated whether predator (larvae of the dragonfly Aeshna Fabricius, 1775) presence elevated the expression level of heat-shock protein 70 (Hsp70)-a commonly found response to stress-in tadpoles of the Common Frog (Rana temporaria L., 1758). In another experiment, we tested the survival of tadpoles in the presence of a free-ranging predator. Prior to this encounter, the tadpoles were exposed to either an Hsp-inducing environmental stress in the form of heat (31 degrees C) or to predator cues from a caged predator. We found no evidence for increased Hsp70 expression in tadpoles either in the presence of fed or starved predators. We did not find any effects of prior exposure to neither heat nor predator presence on survival at the end of experiment. Our results do not point to either Hsp70-mediated effect of predator-induced responses or to beneficial effects of the stress response on survival under predation risk.

  • 4.
    Hyeun-Ji, Lee
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Johansson, Frank
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Compensating for a bad start: compensatory growth across life stages in an organism with a complex life cycle2016In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 94, no 1, p. 41-47Article in journal (Refereed)
    Abstract [en]

    Organisms with a complex life cycle are characterized by a life-history shift through metamorphosis and include organisms such as insects and amphibians. They must optimize their use of resources and behaviour across different life stages to maximize their fitness. An interesting question with regard to such life-history shifts is whether growth in the juvenile stage can be compensated for in the adult stage. Here we ask whether emerald damselflies (Lestes sponsa (Hansemann, 1823)) are able to compensate for depressed growth during the juvenile aquatic stage in their terrestrial adult stage. Lestes sponsa emerge at a fixed adult body size, but feed during the adult stage and are thus able to gain mass as adults. We performed a mark-recapture study to answer whether individuals that emerge from metamorphosis with a low mass are able to compensate by subsequent mass gain during the adult stage. Results showed that compensatory mass gain occurred in the adult stage such that small individuals gained more mass than large individuals. We also found that females gained more mass than males. However, individuals that emerged at a low mass still had lower mass as mature adults than individuals that emerged at a high mass, suggesting that compensation was not complete. This suggests that larval ecology and adult fitness are tightly linked and future research should focus more on elucidating the nature of this relationship.

  • 5. Mayer, Ian
    et al.
    Rosenqvist, Gunilla
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Borg, Bertil
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Schulz, Rüdiger W.
    Plasma-levels of sex steroids in 3 species of pipefish (Syngnathidae)1993In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 71, no 9, p. 1903-1907Article in journal (Refereed)
    Abstract [en]

    The pipefishes (Syngnathidae) are marine teleosts in which the males brood the young. In some species sex-role reversal occurs when, contrary to the usual pattern, females compete more intensely than males for access to mates. This paper reports an investigation of the sex hormones of males and females to see whether they deviate from the ''normal'' teleost pattern. To that end, plasma levels of the androgens testosterone (T), 11-ketotestosterone (OT), 11beta-hydroxytestosterone, 11-ketoandrostenedione, and 11beta-hydroxyandrostenedione (OHA), together with 17alpha-hydroxy-20beta-dihydroprogesterone (17,20-P) and 17beta-estradiol (E2), were measured by means of radioimmunoassay in three species of pipefish: Nerophis ophidion, Syngnathus typhle, and Syngnathus acus. Plasma levels of OT, the dominant circulating androgen in breeding males of most teleost species, was found to be highest in breeding males and low or non-detectable later in the brooding males. This observed decline in male OT levels from the prespawning to the postspawning (=brooding) period is in general agreement with what has been found in other teleosts. In both breeding and brooding S. acus males, T was quantitatively the dominant androgen, whereas OHA was the major androgen in S. acus females, as well as in the females and breeding or brooding males of both S. typhle and N. ophidion. In breeding S. acus and S. typhle males the levels of T, OHT, and OT were higher than in corresponding brooding males and females. The 17,20-P level was below detection limit. E2 was also usually non-detectable, but was most consistently found in breeding Syngnathus males.

  • 6.
    Orizaola, German
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Population and Conservation Biology.
    Laurila, Anssi
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Population and Conservation Biology.
    Growing with kin does not bring benefits to tadpoles in a genetically impoverished amphibian population2008In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 86, no 1, p. 45-50Article in journal (Refereed)
    Abstract [en]

    The effect of intraspecific competition can be modified through the interaction with genetic relatedness among the competing individuals. Theory of kin selection predicts that organisms should modify their behaviour to increase the fitness of their relatives and consequently their inclusive fitness. However, in populations with low genetic variation, the recognition of kin and nonkin individuals could be compromised. In this study, we tested the influence of density and relatedness on larval development in a genetically impoverished population of the pool frog (Rana lessonae Camerano, 1882), exposing individuals from four families to two densities and to competition by full-sibling and nonkin larvae. Larvae in high-density treatment were smaller than those in low-density treatment. No effect of kin, or interaction between density and kin, was detected. However, significant differences were detected in body size among the families and high heritability for size was found in both densities. Lack of variation in recognition alleles may explain the lack of kin effects on growth, whereas variation has been maintained in life-history traits either owing to their polygenic inheritance or owing to maternal effects.

  • 7.
    Orizaola, German
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution.
    Laurila, Anssi
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution.
    Intraspecific variation of temperature-induced effects on metamorphosis in the pool frog (Rana lessonae)2009In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 87, no 7, p. 581-588Article in journal (Refereed)
    Abstract [en]

    Understanding the factors that affect the process of metamorphosis in species with complex life cycles, and in particular their variation within and among populations, has been rarely explored until recently. We examined the effects of temperature environment on several metamorphic characteristics in three populations of the pool frog (Rana lessonae Camerano, 1882) by rearing individuals at two temperature environments (20 and 25 degrees C). Higher temperature shortened the metamorphic period and reduced the absolute mass loss, although there was no difference between the temperatures in the percentage of mass lost. No differences among the populations were detected, but there was significant intrapopulation variation both in the mean and in the plasticity for the duration of metamorphosis. These results indicate that several aspects of metamorphosis are plastic in amphibians, these traits may have considerable intrapopulation variation, and that temperature is a strong factor affecting the process of metamorphosis.

  • 8.
    Outomuro, David
    et al.
    Biología de Organismos y Sistemas, University of Oviedo.
    Cordero-Rivera, Adolfo
    Univ Vigo, Dept Ecol & Biol Anim, E-36005 Pontevedra, Spain.
    Allometry of secondary, primary and non-sexual traits in the beautiful demoiselle (Calopteryx virgo)2012In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 90, p. 1094-1101Article in journal (Refereed)
    Abstract [en]

    The static allometry between the size of a trait and the body size results from the net selection forces acting on the evolution of both the trait and the body size. An increased knowledge of the functional significance of traits is necessary to understand observed allometric patterns. We studied several traits of males of the beautiful demoiselle (Calopteryx virgo meridionalis Selys, 1873), for which there is a good functional knowledge of the genitalic traits and ornaments. We found positive allometry for the wing spot size (considered a secondary sexual trait) and for the distal width (but not length) of the anal appendages, which are used for grasping the female prior to copulation. Regarding the male secondary genitalia, the length but not the width of the big horns of the aedeagus showed an isometric pattern. The aedeagus shaft length showed a negative allometric pattern, while its distal width did not show a significant regression. The slopes of the regressions were higher when using wing length than when using body length as estimators of body size, with the exception of wing spot length. Results are discussed based on the functional significance of the study traits, as well as the pre- and post-copulatory selective pressures acting on them.

  • 9. Pelabon, C
    et al.
    Komers, P E
    Hoglund, J
    Do leks limit the frequency of aggressive encounters in fallow deer?: Linking local male density and lek occurrence1999In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 77, no 4, p. 667-670Article in journal (Refereed)
  • 10.
    Persson, M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Population and Conservation Biology.
    Räsänen, Katja
    Laurila, Anssi
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Population and Conservation Biology.
    Merilä, Juha
    Maternally determined adaptation to acidity in Rana arvalis: Are laboratory and field estimates of embryonic stress tolerance congruent?2007In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 85, no 7, p. 832-838Article in journal (Refereed)
    Abstract [en]

    Geographic variation indicating local adaptation, as well as its quantitative genetic basis, is commonly investigated in common garden experiments in the laboratory. However, the applicability of laboratory results to the complex conditions experienced by populations in the wild may be limited. Our previous laboratory experiments showed maternally determined local adaptation in embryonic acid-stress tolerance (viz. survival) of the moor frog, Rana arvalis Nilsson, 1842. Here we tested whether this laboratory finding holds even when embryos are exposed to acid stress in the wild. We conducted reciprocal crosses between an acid-origin population and a neutral-origin population of R. arvalis and transplanted the embryos to an acid site (pH ~4) in the field. Embryonic survival was much lower in the field experiment than in previous laboratory experiments, but, consistent with laboratory work, embryos from acid-origin females had threefold higher survival than embryos from neutral-origin females. These results suggest that laboratory tests can provide appropriate estimates of among population variation, as well as the quantitative genetic basis of acid-stress tolerance in amphibians.

1 - 10 of 10
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf