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Can climate change exacerbate the genetic consequences of forest fragmentation? Effects of drought stress on heterozygosity-fitness correlations in pedunculate oak

Research output: Contribution to conferencePaper/Powerpoint/Abstract


  • Guy Vranckx
  • Hans Jacquemyn
  • Pieter Janssens
  • Bie Gielen
  • Bart Muys
  • Olivier Honnay

External Organisations

  • KULeuven
  • Bodemkundige Dienst van België


Original languageEnglish
Number of pages1
Publication statusPublished - 2013
EventClimTree 2013, International Conference on Climate Change and Tree Responses in Central European Forests - Zurich, Switzerland
Duration: 1-Sep-20135-Sep-2013


ConferenceClimTree 2013, International Conference on Climate Change and Tree Responses in Central European Forests


In small and spatially isolated forest fragments, increased homozygosity may directly affect individual tree fitness, through the expression of deleterious alleles that influence morphological and physiological traits. Climate change induced drought may exacerbate the detrimental genetic consequences of forest fragmentation because the fitness response to low levels of heterozygosity is generally thought to be more pronounced under environmental stress than under optimal conditions. To test this hypothesis, we performed a greenhouse experiment in which fitness traits of 6-months-old seedlings of Quercus robur, differing in multi-locus heterozygosity (MLH), were recorded during 3 months under both a well-watered and a drought stress treatment (50 seedlings per treatment). Heterozygosity-fitness correlations (HFC) were examined by correlating transpiration parameters and various growth traits of individual trees to their MLH and by studying their response to drought stress. We obtained weak, but significant effects of the MLH ( = 3–11%, p < 0.05) on several fitness traits. High atmospheric stress (e.g. high vapor pressure deficit (VPD) influenced the strength of the HFCs of the transpiration parameters, whereas only a limited effect of the irrigation treatment was observed. Considering ongoing climate change, increased VPD levels in the future may strengthen the negative fitness responses of trees to low MLH.

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