The evolution of variable offspring provisioning

Martin Dziminski

    Research output: ThesisDoctoral Thesis

    82 Downloads (Pure)

    Abstract

    Most theoretical models predict an optimal offspring size that maximises parental fitness. Variation in the quality of the offspring environment can result in multiple offspring size optima and therefore variation of offspring provisioning can evolve. Variation in offspring provisioning is common and found across a variety of taxa. It can be defined as between populations, explained by optimality models, or between and within individuals, neither so easily explained by optimality models. My research focused on the evolution of variable offspring provisioning by testing theoretical models relating to variation in offspring provisioning between and within individuals. Using comparative methods, I found a positive relationship between intraclutch variation in offspring provisioning and variation in the quality of the offspring environment in a suite of pond breeding frogs. This positive relationship provided evidence that patterns of variable offspring provisioning are related to the offspring environment. This study also identified a species (Crinia georgiana) with high variation in offspring provisioning on which to focus further investigations. High variation in offspring provisioning occured between and within individuals of this species independent of female phenotype and a trade-off in offspring size and number existed. In laboratory studies, increased yolk per offspring led to increased fitness per offspring. Parental fitness calculations revealed that in high quality conditions production of small more numerous offspring resulted in higher parental fitness, but in lower quality conditions the production of large offspring resulted in the highest parental fitness. This was confirmed in field experiments under natural conditions using molecular markers to trace offspring to clutches of known provisioning, allowing me to measure exact parental fitness. The strategy of high variation in offspring size within clutches can be of benefit when the future of the offspring environment is not known to the parents: as a form of bet-hedging. Further study of the offspring environment revealed that conditions such as density dependent fitness loss, spatial variation in habitat quality, and non-random offspring dispersal, can combine to create the conditions predicted by theoretical models to maintain a strategy of variable offspring provisioning in the population. My research provides a comprehensive empirical test of the theory of variable offspring provisioning
    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - 2005

    Fingerprint Dive into the research topics of 'The evolution of variable offspring provisioning'. Together they form a unique fingerprint.

  • Cite this