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Hirsch, Philipp E
Publications (2 of 2) Show all publications
Bartels, P., Hirsch, P. E., Svanbäck, R. & Eklöv, P. (2012). Water transparency drives intra-population divergence in Eurasian perch (Perca fluviatilis). PLoS ONE, 7(8), e43641
Open this publication in new window or tab >>Water transparency drives intra-population divergence in Eurasian perch (Perca fluviatilis)
2012 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 8, p. e43641-Article in journal (Refereed) Published
Abstract [en]

Trait combinations that lead to a higher efficiency in resource utilization are important drivers of divergent natural selection and adaptive radiation. However, variation in environmental features might constrain foraging in complex ways and therefore impede the exploitation of critical resources. We tested the effect of water transparency on intra-population divergence in morphology of Eurasian perch (Perca fluviatilis) across seven lakes in central Sweden. Morphological divergence between near-shore littoral and open-water pelagic perch substantially increased with increasing water transparency. Reliance on littoral resources increased strongly with increasing water transparency in littoral populations, whereas littoral reliance was not affected by water transparency in pelagic populations. Despite the similar reliance on pelagic resources in pelagic populations along the water transparency gradient, the utilization of particular pelagic prey items differed with variation in water transparency in pelagic populations. Pelagic perch utilized cladocerans in lakes with high water transparency and copepods in lakes with low water transparency. We suggest that under impaired visual conditions low utilization of littoral resources by littoral perch and utilization of evasive copepods by pelagic perch may lead to changes in morphology. Our findings indicate that visual conditions can affect population divergence in predator populations through their effects on resource utilization.

National Category
Biological Sciences
Identifiers
urn:nbn:se:uu:diva-158689 (URN)10.1371/journal.pone.0043641 (DOI)000308063700123 ()
Available from: 2011-09-13 Created: 2011-09-13 Last updated: 2017-12-08Bibliographically approved
Hirsch, P. E. (2011). Phenotypic Processes Triggered by Biological Invasions. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Phenotypic Processes Triggered by Biological Invasions
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Individuals within a single population can vary widely in their phenotype e.g. in their body shape. These differences are an important source of biodiversity and they can precede evolutionary divergence within a population.

In this thesis we use the biological invasion of the zebra mussels into Swedish lakes to investigate which processes create or maintain phenotypic diversity within populations of the two native fish species perch and roach and the mussel itself. Both fishes have specially adapted body shapes that depend on whether they feed in the near-shore or open-water habitat of lakes. This habitat-specific divergence was more pronounced in lakes with zebra mussels, probably because resources in both habitats were in higher supply due to the mussels’ effects on the lakes. Divergence in perch body shapes between habitats was also higher in lakes with a higher water clarity, suggesting that visual conditions can affect the resource use and thus also the expression of a habitat-specific body shape.

When investigating the diversity of body shapes in the mussel itself we found that mussels from one lake changed their shell shape when exposed to different predators: fish predators induced a more elongated shell shape while crayfish predators induced a rounder shell. These specific shell shapes probably serve as two alternative predator defenses protecting the mussel from predation.

We conclude that the availability and use of distinct resources is an important source of diversity within populations. Abiotic conditions can play a previously underappreciated role by promoting or impairing the use of the distinct resources thus affecting the divergence. The diversity of shell shapes we found in the zebra mussels complements our study by demonstrating that not only consumer responses to resources but also resources’ responses to predators can generate phenotypic diversity.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2011. p. 44
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 853
Keywords
Resource polymorphism, phenotypic plasticity, phenotypic divergence, anti-predator responses, Perca fluviatilis, Rutilus rutilus, Dreissena polymorpha
National Category
Biological Sciences
Research subject
Biology with specialization in Limnology
Identifiers
urn:nbn:se:uu:diva-158697 (URN)978-91-554-8157-5 (ISBN)
Public defence
2011-10-28, Ekmansalen, Norbyvägen 14, Uppsala, 10:00 (English)
Opponent
Supervisors
Available from: 2011-10-06 Created: 2011-09-13 Last updated: 2012-05-31
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