Family planning under social competition

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Competition is an essential part of evolution. Animals compete over resources as food, partners and breeding sites. Individuals with characteristics that enable them to outcompete others and gain access to vital resources will be able to produce more offspring and thereby contribute more to future generations (fitness). Experimental research on great tits (Parus major) showed that the family size that parents raise can negatively affect their future survival probability in areas with high competitive pressure. The hypothesis was formulated that family size may negatively affect the competitive ability of parents in later life. Under competition it may thus be more favorable for parents to raise smaller families. The focus of my thesis was to experimentally test this hypothesis in a great tit nest box population. We manipulated the family size that great tit parents had to raise by taking away or adding nestlings to broods. Next, we induced competition among the tits in winter for food and sleeping places and in spring for suitable breeding sites. We found evidence that the manipulated family size had a negative effect on the probability of parents to 1) claim food in winter and 2) claim breeding sites safe from nest predation next spring. This evidence is consistent with the hypothesis that family size negatively affects the competitive ability of parents. My work contributes to our understanding how social mechanisms such a competition can affect individual reproductive behaviour. This knowledge is essential to predict how animals will respond to changes in their ecological environment.
Translated title of the contributionOptimale voortplanting in de competitieve omgeving
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • University of Groningen
  • Tinbergen, Joost, Supervisor
  • Both, Christiaan, Supervisor
Award date29-Sep-2017
Place of Publication[Groningen]
Print ISBNs978-94-034-0027-3
Electronic ISBNs978-94-034-0030-3
Publication statusPublished - 2017

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