The Effect of Variation in Developmental Mode on the Population Dynamics of a Spionid Polychaete (Pygospio elegans) in a Heterogeneous Environment

Anne Thonig

Research output: Book/ReportPh.D. thesisResearch

Abstract

The effect of variation in developmental mode on the population dynamics of a
spionid polychaete (Pygospio elegans) in a heterogeneous environment.
Yhteenveto: Kehitysmuotojen variaatio ja sen vaikutus Pygospio elegans -
monisukasmadon populaatiodynamiikkaan heterogeenisessä ympäristössä.
Oversigt: Effekten af variation I developmental mode på populationsdynamikken
af en spionid børsteorm (Pygospio elegans) i et heterogent miljø.
There is a great diversity in larvae of marine invertebrates. To understand the
causes and consequences of different modes of development on population
dynamics, study of poecilogonous species that show a polymorphism in
developmental mode might be more useful than are comparisons between
species, since no confounding effects due to speciation arise. In this study, I
documented the population ecology and genetics of the poecilogonous
polychaete P. elegans and investigated the impact of abiotic and biotic variables
on population dynamics. Four focal populations from the Isefjord-RoskildeFjord
estuary complex, Denmark were sampled over one year. I observed
highly dynamic population structure in both size cohort data and population
genetic data that is possibly explained by the short life span of P. elegans and
sweepstakes reproductive success. Additionally, stochastic events, such as rain
storms, can lead to abrupt drops in salinity which can be detrimental for P.
elegans and hence introduce further changes in population structure. Seasonal
dynamics, including sexual reproduction, were correlated with temperature,
whereas spatial differences in density, size and reproductive activity of P.
elegans as well as species diversity of the benthic invertebrate community, were
related to sediment structure. A positive correlation between species and allelic
richness of P. elegans might indicate that environmental impacts are of greater
importance in shaping population dynamics than are species interactions.
Switches in developmental mode could reflect a strategy for coping with life in
an unpredictable, heterogeneous habitat. Although switches in developmental
mode were correlated with the appearance of genetically differentiated size
cohorts, environmental or epigenetic effects cannot be ruled out.
Original languageEnglish
Place of PublicationRoskilde
PublisherRoskilde Universitet
Number of pages72
Publication statusPublished - 12 Jan 2018

Keywords

  • Benthic invertebrates
  • Isefjord-Roskilde-Fjord
  • Pygospio elegans
  • population ecology and genetics
  • poecilogony
  • life history
  • estuary complex

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