Change search
ReferencesLink to record
Permanent link

Direct link
Growth of whitefish ecotypes: A comparison of individual growth rates in monomorphic and polymorphic populations
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
2013 (English)Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
Abstract [en]

In resource polymorphism, ecological opportunity and selective predatory pressure can be considered key factors in phenotypic divergence. In post-glacial lakes of Scandinavia, the European whitefish (Coregonus lavaretus L.) is a common species and has repeatedly diverged along the benthic - pelagic resource axis. Recent studies suggest that predation by northern pike (Esox lucius L.) induces rapid divergence in whitefish, leading to two reproductively isolated ecotypes: a dwarf planktivore and a giant benthivore. In lakes where pike is absent, whitefish are only found as monomorphic populations. In this study I estimated growth rates in two monomorphic and two polymorphic populations having giant and dwarf ecotypes. The aim was to use growth rates as a tool to distinguish between juvenile giants and dwarfs, but also to find out if a population's resource use was reflected in the growth rate. Scales were used to calculate growth rate, where like trees, variations in seasonal growth could be observed in a ring-like structure. Growth rates differed between the morphs, and mirrored their use of resources. The two monomorphic populations had the highest average growth rate the first six years (40.1 and 35.5 mm/year), and quickly reached maximum size. Dwarfs and giants in the dimorphic systems had equal growth the first two years, after which giants grew at a substantially higher rate. Categorization between juvenile giants and dwarfs could be done if an individual had passed its third growth season.

Place, publisher, year, edition, pages
2013. , 17 p.
Keyword [en]
whitefish, growth rate, scales, pike, polymorphism
National Category
URN: urn:nbn:se:umu:diva-81539OAI: diva2:656026
Educational program
Bachelor of Science in Biology and Earthscience
Available from: 2013-10-15 Created: 2013-10-14 Last updated: 2013-10-15Bibliographically approved

Open Access in DiVA

Bachelor Thesis - Fredrik Olajos(807 kB)165 downloads
File information
File name FULLTEXT01.pdfFile size 807 kBChecksum SHA-512
Type fulltextMimetype application/pdf

By organisation
Department of Ecology and Environmental Sciences

Search outside of DiVA

GoogleGoogle Scholar
Total: 165 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 115 hits
ReferencesLink to record
Permanent link

Direct link