Trait values of individuals are affected not only by their genetic makeup, but also by environmental factors and
interactions with other individuals. The heritable effect of an individual on the trait values of other individuals
it interacts with is known as an indirect genetic effect (IGE). Such IGEs may affect response to selection. Fish selected
for high growth rate, for example, have been shown to be more aggressive and competitive, which may
reduce the observed response in growth rate. The main objective of this study is to quantify the genetic and
non-genetic indirect effects for harvest weight in the GIFT strain of Nile tilapia. A total of 6330 fish with harvest
weight information were used to estimate genetic and non-genetic parameters. A bivariate analysis of harvest
weight and survival was conducted by fitting different mixed models to investigate the presence of IGEs and
other non-genetic effects. The full set of genetic parameters could not be estimated simultaneously with the inclusion
of maternal common environmental effects. A confounding between maternal common environmental
effects and direct genetic effects resulted from the mating strategy, where one sire was mated to only one or
two dams. A 1 male to 2 females mating design is common in aquaculture, but it has limited power to estimate
genetic parameters. Models without maternal common environmental effects showed significant IGE on harvest
weight, which contributed 48% of total heritable variance. Models with maternal common environmental
effects suggested the presence of IGE. The direct–indirect genetic correlation for harvest weight was negative
(−0.38 ± 0.19), indicating that traditional selection, if performed in an environment where the fish have to compete
with each other for the resources, will increase competition. A strongly negative genetic correlation between
direct effects on survival and indirect effects on harvest weight (−0.79 ± 0.30) showed that individuals with
better genes for survival suppressed growth rate of their social partners. Our results suggest that heritable competitive
interactions affect harvest weight in Nile tilapia. Hence, breeding schemes may need to be adapted to
avoid an increase in aggressiveness due to selection for growth rate in a competitive environment. Further
studies are required to investigate the relevance of IGE and its implications on different systems of commercial
aquaculture production.
Statement of relevance: Sociable fish will help to improve aquaculture production
Trait values of individuals are affected not only by their genetic makeup, but also by environmental factors andinteractions with other individuals. The heritable effect of an individual on the trait values of other individualsit interacts with is known as an indirect genetic effect (IGE). Such IGEs may affect response to selection. Fish selectedfor high growth rate, for example, have been shown to be more aggressive and competitive, which mayreduce the observed response in growth rate. The main objective of this study is to quantify the genetic andnon-genetic indirect effects for harvest weight in the GIFT strain of Nile tilapia. A total of 6330 fish with harvestweight information were used to estimate genetic and non-genetic parameters. A bivariate analysis of harvestweight and survival was conducted by fitting different mixed models to investigate the presence of IGEs andother non-genetic effects. The full set of genetic parameters could not be estimated simultaneously with the inclusionof maternal common environmental effects. A confounding between maternal common environmentaleffects and direct genetic effects resulted from the mating strategy, where one sire was mated to only one ortwo dams. A 1 male to 2 females mating design is common in aquaculture, but it has limited power to estimategenetic parameters. Models without maternal common environmental effects showed significant IGE on harvestweight, which contributed 48% of total heritable variance. Models with maternal common environmentaleffects suggested the presence of IGE. The direct–indirect genetic correlation for harvest weight was negative(−0.38 ± 0.19), indicating that traditional selection, if performed in an environment where the fish have to competewith each other for the resources, will increase competition. A strongly negative genetic correlation betweendirect effects on survival and indirect effects on harvest weight (−0.79 ± 0.30) showed that individuals withbetter genes for survival suppressed growth rate of their social partners. Our results suggest that heritable competitiveinteractions affect harvest weight in Nile tilapia. Hence, breeding schemes may need to be adapted toavoid an increase in aggressiveness due to selection for growth rate in a competitive environment. Furtherstudies are required to investigate the relevance of IGE and its implications on different systems of commercialaquaculture production.Statement of relevance: Sociable fish will help to improve aquaculture production
การแปล กรุณารอสักครู่..
![](//thimg.ilovetranslation.com/pic/loading_3.gif?v=b9814dd30c1d7c59_8619)