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Variation in life-history strategies among sympatric anadromous populations of pike (Esox lucius)
Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
2013 (English)Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
Abstract [en]

The life-history theory seeks to explain and predict how natural selection moulds life-histories. One prediction is that age-specific extrinsic mortality will shape strategies of energy allocation between reproduction, growth and maintenance. Here, I have studied variation in life-history strategies among 4 coexisting populations of pike (Esox lucius) in the Baltic Sea, only separated during spawning due to their natal homing behaviour. The environment differs between spawning areas, which can impose different age-specific mortality rates and consequently different optimal life-history strategies. The aim of this study was to compare life-history traits between anadromous populations of pike, with the hypothesis that populations will differ in their life-history strategies. Approximately 20 (15-23) females were sampled from each population during spawning migration. Fecundity, egg size and reproductive effort were quantified through estimates of the absolute numbers of eggs, egg densities and measurements of gonad dry mass, respectively. Growth was determined by analyzing growth increments in cleithra, while mass-length relationship was used to assess the condition. Reproductive effort, fecundity and egg size differed significantly, giving every population its own suite of pike life-history characteristics. These results, together with a consistent somatic condition suggest different strategies of energy allocation between populations, despite the intraspecific level and the fact that populations only separate during spawning. I propose that this reflect local adaptations in line with predictions of the life-history theory.

Abstract [sv]

Livshistorieteorin ämnar förklara och förutsäga hur livshistorier formas genom naturlig selektion där åldersspecifik mortalitet spås ha inverkan på optimala strategier för energiallokeringen mellan reproduktion, tillväxt och underhåll. I Kalmarsund (Östersjön) samexisterar ett flertal populationer av gädda (Esox lucius) som skiljer sig genetiskt på grund av deras hemortstrohet. De delar en gemensam miljö i Kalmarsund under större delen av livscykeln, men förhållandena skiljer sig åt mellan deras lekhabitat, vilket kan leda till skillnader i åldersspecifik mortalitet mellan populationer och därmed olika optimala livshistoriestrategier. Syftet med den här studien var att jämföra livshistorieegenskaper mellan sötvattenlekande populationer av gädda i Kalmarsund, med hypotesen att det finns populationsspecifika livshistoriestrategier. Detta undersöktes med en fältstudie där gädda samlades in från fyra olika populationer under lekvandringen. Fekunditet, romstorlek och reproduktiv investering kvantifierades för varje individ genom mätningar av totalt antal romkorn, densitet av romkorn respektive gonadvikt. Tillväxten undersöktes genom att analys av tillväxtzoner i cleithra samtidigt som vikt i förhållande till längd användes som ett mått på kondition. Reproduktiv investering, fekunditet och romstorlek skiljde sig signifikant mellan populationer, men det fanns inga skillnader i somatisk kondition. Resultaten tyder sammataget på populationsspecifika strategier för energiallokering, vilket har konsekvenser för förvaltningen av gäddpopulationer och antyder lokala anpassningar.

Place, publisher, year, edition, pages
2013. , p. 28
Keywords [en]
Life-history, pike, esox lucius, fecundity, reproductive effort
National Category
Biological Sciences
Identifiers
URN: urn:nbn:se:lnu:diva-31283OAI: oai:DiVA.org:lnu-31283DiVA, id: diva2:680194
Subject / course
Biology
Educational program
Akvatisk ekologi, masterprogram, 120 hp
Supervisors
Examiners
Available from: 2013-12-22 Created: 2013-12-17 Last updated: 2013-12-22Bibliographically approved

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CiteExportLink to record
Permanent link

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Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
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More styles
Language
  • de-DE
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Output format
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