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Area of Science:

  • Evolutionary biology
  • Population genetics
  • Fisheries science

Background:

  • Size-selective harvesting is a common practice in fisheries and hunting.
  • Changes in mean trait values are well-studied, but changes in trait variability are less understood.
  • Directional selection is often assumed to reduce phenotypic variation.

Purpose of the Study:

  • To investigate the impact of size-selective harvesting on trait variability.
  • To determine if directional selection for large body size affects body-size variation.
  • To explore the role of feeding environments in this process.

Main Methods:

  • Experimental harvesting of zebrafish (Danio rerio) populations.
  • Exposure to two feeding environments: ad libitum and temporarily restricted food.
  • Analysis of body-size variation under directional selection for large individuals.

Main Results:

  • Directional selection for large body size increased body-size variation in zebrafish populations.
  • This effect was observed in both feeding environments.
  • Large individuals were found to harbor significant variation within the population.

Conclusions:

  • Size-selective harvesting favoring large individuals can enhance trait variability.
  • Protecting large individuals is important for maintaining population diversity.
  • This finding has implications for sustainable management of fish stocks.