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Ontogeny and Population Biology of a Sex-Limited Colour Polymorphism

Författare:
Publiceringsår: 2006
Språk: Engelska
Sidor: 110
Dokumenttyp: Doktorsavhandling
Förlag: Xanto Grafiska AB
Ytterligare information: E.I. Svensson, J. Abbott and R. Härdling. 2005. Female polymorphism, frequency dependence, and rapid evolutionary dynamics in natural populations. Am. Nat., pp 567-576. University of Chicago Press J. Abbott and E.I. Svensson. 2005. Phenotypic and genetic variation in emergence and development time of a trimorphic damselfly. J. Evol. Biol., pp 1464-1470. Blackwell J.K. Abbott and E.I. Svensson. 2006. Ontogeny of sexual dimorphism and phenotypic intergration in heritable morphs. (submitted) J.K. Abbott, E.I. Svensson and T. Gosden. . Adaptive morphological variation in an intraspecific mimicry system. (manuscript) E.I. Svensson and J. Abbott. 2005. Evolutionary dynamics and population biology of a polymorphic insect. J. Evol. Biol., pp 1503-1514. Blackwell J.K. Abbott, S. Bensch, T. Gosden and E.I. Svensson. . Rapid evolutionary dynamics in a polymorphic non-equilibrium system. (manuscript)

Sammanfattning

This study has involved investigation of number of populations of the damselfly Ischnura elegans over several years, looking at frequency changes over time, morphological differences between the sexes and the morphs, differences in growth rate and development time, differences in fecundity between the morphs, and genetic differentiation between populations. I. elegans is a small annual damselfly with three female colour morphs (Androchrome, Infuscans, and Infuscans-obsoleta), one of which (the Androchrome) is considered a male mimic; males are monomorphic.

Empirically estimated selection coefficients were used in a population genetic and dynamic model with environmental variation which predicted coexistence of the three morphs. This suggests that negative frequency-dependence on fecundity mediated by male mating harassment is sufficient to explain coexistence of the morphs. Field data also showed that fecundity decreased with increasing frequency in the population for all three morphs. Investigation of sexual dimorphism revealed that the sexes differed in development time, growth rates, and adult size and shape and that sexual size dimorphism is produced in I. elegans by a combination of development time and development rate acting in concert. The female morphs also differed in development time, growth rates, and adult size and shape, although in this case effects of development time and development rate cancelled each other out. In addition, male-like body shape had a negative effect on fecundity in Infuscans-obsoleta females but not in Androchrome or Infuscans females. Quantitative genetic parameters for morphological traits showed that an evolutionary response to selection on body shape is possible. Comparisons of Fst-values and the lack of isolation by distance both suggest that this is a highly dynamic non-equilibrium system, and genetic diversity appears to be influenced by wind direction.

The results in this study indicate that the morphs are subject to negative frequency-dependent selection via male mating harassment, and that the differences between the morphs are part of their identity as alternative adaptive strategies.

Disputation

2006-11-23
09:00
Blue Hall, Ecology Building, Sölvegatan 37, Lund
  • Daniel Promislow (Dr.)

Nyckelord

  • Biology and Life Sciences
  • Earth and Environmental Sciences
  • embryologi
  • ontogeni
  • animal morphology
  • embryology
  • Utvecklingsbiologi
  • Damselflies
  • Colour polymorphism
  • Development
  • Frequency-dependence
  • Morphology
  • growth (animal)
  • ontogeny
  • Animal anatomy
  • Development biology
  • Djurs anatomi och morfologi
  • Population divergence
  • Animal ecology
  • Djurekologi

Övriga

  • Erik I. Svensson
  • ISBN: 91-7105-243-7

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