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Transcriptomic response to aquaculture intensification in Nile tilapia
Evolutionary Applications, Volume: 12, Issue: 9, Pages: 1757 - 1771
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To meet future global demand for fish protein, more fish will need to be farmed usingfewer resources, and this will require the selection of nonaggressive individuals thatperform well at high densities. Yet, the genetic changes underlying loss of aggressionand adaptation to crowding during aquacultu...
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To meet future global demand for fish protein, more fish will need to be farmed usingfewer resources, and this will require the selection of nonaggressive individuals thatperform well at high densities. Yet, the genetic changes underlying loss of aggressionand adaptation to crowding during aquaculture intensification are largely unknown.We examined the transcriptomic response to aggression and crowding in Nile tilapia,one of the oldest and most widespread farmed fish, whose social structure shiftsfrom social hierarchies to shoaling with increasing density. A mirror test was usedto quantify aggression and skin darkening (a proxy for stress) of fish reared at lowand high densities, and gene expression in the hypothalamus was analysed amongthe most and least aggressive fish at each density. Fish reared at high density weredarker, had larger brains, were less active and less aggressive than those reared atlow density and had differentially expressed genes consistent with a reactive stress-copingstyle and activation of the hypothalamus–pituitary–interrenal (HPI) axis.Differences in gene expression among aggressive fish were accounted for by densityand the interaction between density and aggression levels, whereas for non-aggressivefish differences in gene expression were associated with individual variation inskin brightness and social stress. Thus, the response to crowding in Nile tilapia iscontext dependent and involves different neuro-endocrine pathways, depending onsocial status. Knowledge of genes associated with the response to crowding maypave the way for more efficient fish domestication, based on the selection of non-aggressiveindividuals with increasing tolerance to chronic stress necessary for aquacultureintensification.
aggression, aquaculture intensification, crowding, fish domestication, gene expression, HPI axis, stress response