In exploited fish species, fisheries-related mortality on adults is significantly higher than natural mortality. Most fishing gears are also positively size-selective. Both elevated and trait-selective harvesting can promote the evolution of a fast life-history, characterized by increased reproductive investment, reduced age and size ate maturity, reduced post maturation growth and reduced longevity. In addition, behavioral changes are likely. Such changes may promote pre- and postzygotic reproductive barriers and foster reproductive isolation among subpopulations. To study this potential, three experimental lines of zebrafish (Danie rerio) that were exposed to either positive (small line), negative (large line) or random (control line) size-selective mortality were used. The prezygotic preference among the three lines was tested through paired mate choice experiments, and postzygotic reproduction through spawning trials in a full factorial design. In the prezygotic tests, it was found that females or males of specific selection lines preferred to associate with other lines. In the postzygotic tests, it was found that males of the control line stimulated the releaseof significantly more eggs than the males of the other two lines. Body size did not affect the results. This study demonstrates that highly intensive size-selective harvesting at per generation mortality rates of 75% does not result in reproductive isolation, and continued gene flow from wild fish into fish sub-populations evolutionarily adapted to high fishing pressure is likely during secondary contact.
Size-selective harvesting and reproductive isolation in zebrafish (Danio rerio)
Fromm, K. (2020). Size-selective harvesting and reproductive isolation in zebrafish (Danio rerio). Master Thesis, Freie Universität Berlin, Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB) in Berlin
Erschienen in: Master Thesis, Freie Universität Berlin, Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB) in Berlin