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Dispersal, inbreeding and fitness in natural populations

Författare:
Publiceringsår: 2003
Språk: Engelska
Sidor: 158
Dokumenttyp: Doktorsavhandling
Förlag: Bengt Hansson, Ecology Building, 223 62 Lund, Sweden,
Ytterligare information: Article: I. Hansson, B., Bensch, S., Hasselquist, D., Lillandt, B.-G., Wennerberg, L. and von Schantz, T. 2000. Increase of genetic variation over time in a recently founded population of great reed warblers (Acrocephalus arundinaceus) revealed by microsatellites and DNA fingerprinting. Mol. Ecol. 9:1529-1538. Article: II. Hansson, B., Bensch, S., Hasselquist, D. and Nielsen, B. 2002. Restricted dispersal in a long-distance migrant bird with patchy distribution, the great reed warbler. Oecologia 130:536-542. Article: III. Hansson, B., Bensch, S. and Hasselquist, D. 2003. A new approach to study dispersal: immigration of novel alleles reveals female-biased dispersal in great reed warblers. Mol. Ecol. In press. Article: IV. Hansson, B., Bensch, S. and Hasselquist, D. 2002. Predictors of natal dispersal in great reed warblers: results from small and large census areas. J. Avian Biol. 33:311-314. Article: V. Hansson, B., Bensch, S. and Hasselquist, D. Heritability of dispersal behaviour in a songbird. Submitted manuscript. Article: VI. Bensch, S., Hasselquist, D., Nielsen, B. and Hansson, B. 1998. Higher fitness for philopatric than for immigrant males in a semi-isolated population of great reed warblers. Evolution 52:877-883. Article: VII. Hansson, B., Bensch, S. and Hasselquist, D. Lifetime fitness of philopatric and genetically different immigrant great reed warblers. Manuscript. Article: VIII. Hansson, B. Marker-based relatedness predicts egg-hatching failure in great reed warblers. Submitted manuscript. Article: IX. Hansson, B. and Westerberg, L. 2002. On the correlation between heterozygosity and fitness in natural populations. Mol. Ecol. 11:2467-2474. Article: X. Hansson, B., Bensch, S. and Hasselquist, D. and Åkesson, M. 2001. Microsatellite diversity predicts recruitment in sibling great reed warblers. Proc. R. Soc. Lond. B 268:1287-1291. Article: XI. Hansson, B., Westerdahl, H., Hasselquist, D., Åkesson, M. and Bensch, S. Linkage disequilibria generate heterozygosity-fitness correlations in great reed warblers . Submitted manuscript.

Sammanfattning

To evaluate how inbreeding affects the viability of small populations, it is crucial to determine what constitutes a population (i.e., the number of breeders in local patches and the degree of dispersal), and also to estimate the reproductive consequences of philopatry and emigration. In this thesis, I concentrate on dispersal, inbreeding and fitness in natural populations. I consider dispersal rates, individual and population parameters predicting dispersal, and reproductive costs and benefits of dispersal. Furthermore, I evaluate how reproductive effects of inbreeding can be quantified by means of genetic markers. I base my arguments on empirical data gathered from newly founded nonequilibrium populations of great reed warblers (Acrocephalus arundinaceus) in Sweden. My results show that it is important to consider scale when evaluating possible predictors of dispersal. This was evident both from a capture-recapture analysis, which revealed that dispersal varied between years on the larger scale and between hatching sites on the smaller scale, and from a molecular analysis, which revealed a sex bias in dispersal on the larger scale that was lacking on the smaller scale. The capture-recapture study also revealed that dispersal was partly heritable in great reed warblers. Occasionally, closely related individuals mated. When this happened, the reproductive success decreased as a result of poor egg-hatching success. Also, there were fitness differences between philopatric and immigrating birds. In males, philopatric individuals had higher life-time mating success than immigrants. In females, on the other hand, short-distance dispersing immigrants recruited a higher proportion of their offspring than both philopatric individuals and long-distance immigrants. This suggests that there exists an optimal dispersal distance in female great reed warblers. Finally, I found that surviving great reed warblers had significantly higher microsatellite heterozygosity than their non-surviving siblings. This result led to a major conclusion in my thesis: that heterozygosity-fitness correlations might occur in nonequilibrium populations for reasons that are neither related to selection at the markers per se, nor to variation in the inbreeding coefficient. Instead, and because of high levels of linkage disequilibria in the population, the association between heterozygosity and survival might have arisen from selection at fitness loci that were linked to the genetic markers.

Disputation

2003-02-21
10:15
Blå Hallen, Ecology Building, Sölvegatan 37, Lund
  • Philip W. Hedrick (Prof)

Nyckelord

  • Earth and Environmental Sciences
  • immigration
  • inbreeding
  • inbreeding depression
  • heterozygosity
  • microsatellite
  • great reed warbler
  • bird
  • Djurekologi
  • Animal ecology
  • philopatry
  • heritability
  • founder event
  • dispersal
  • bottleneck

Övriga

  • Molecular Ecology and Evolution Lab
  • ISBN: 91-7105-184-8
  • ISRN: SE-LUNBDS/NBZE-03/1095+158 pp

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