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Seasonal time-constrains, compensatory strategies and life history switch points in larval amphibians
Uppsala University, Disciplinary Domain of Science and Technology.
(English)Manuscript (preprint) (Other academic)
URN: urn:nbn:se:uu:diva-145023OAI: oai:DiVA.org:uu-145023DiVA: diva2:395198
Available from: 2011-02-04 Created: 2011-02-04 Last updated: 2011-03-11
In thesis
1. Physiological and Environmental Processes Influencing Growth Strategies in Amphibian Larvae
Open this publication in new window or tab >>Physiological and Environmental Processes Influencing Growth Strategies in Amphibian Larvae
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Cost and benefits of high individual growth rates are likely to vary across different environments leading to geographic differentiation in growth strategies. In ectotherms, habitats constrained by short growing seasons favour rapid growth and development leading to adaptive latitudinal clines in these traits. Geographic variation in growth strategies should be influenced by physiological variation as well as environmental factors, however many of these mechanisms remain largely unexplored. In my thesis, I studied hormonal correlates of growth strategies, and compensatory responses to phenological variation and environmental stress in anuran tadpoles. I tested the hypotheses that fast growing high latitude common frog Rana temporaria tadpoles have higher growth hormone (GH) expression, and low stress hormone (CORT) elevation in response to predator stress. I found no relationship between GH expression and latitude, but CORT response decreased with latitude after 24 hours of predator exposure. Lower CORT response at high latitude can be adaptive as it may enable the tadpoles to maintain high growth in time constrained habitats. I also found that breeding phenology affected latitudinal variation in growth, development and anti-predator strategies. Northern R. temporaria tadpoles were phenotypically more similar to southern tadpoles when breeding occurred early, suggesting that part of the latitudinal variation is plastic and affected by yearly variation in phenology. When time stress was manipulated by delaying hatching, tadpoles were able to compensate by increasing their development and growth during the larval stage, decreasing the cost of the delayed development. In the final study, I found that northern tadpoles showed stronger compensatory growth during the larval stage than southern tadpoles after being delayed by low food, however, temperature manipulation did not induce differences in the compensatory responses. In general, my results highlight the roles of both environmental and genetic variation in determining individual growth strategies.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2011. 46 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 805
growth; growth strategies; amphibians; latitudinal gradient; growth hormone (GH); corticosterone (CORT); breeding phenology; compensatory growth; compensatory strategies
National Category
Biological Sciences
Research subject
Biology with specialization in Population Biology
urn:nbn:se:uu:diva-145024 (URN)978-91-554-7998-5 (ISBN)
Public defence
2011-03-18, Lindahlssalen, Norbyvägen 18 B, Uppsala, 09:00 (English)
Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 735Available from: 2011-02-25 Created: 2011-02-04 Last updated: 2011-03-21

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