Behavioural changes as a correlated response to selection

Group feeding behavior of brown trout is a correlated response to selection for growth shaped by the environment

Group feeding pattern is a response correlated to selection for growth in brown trout. Previous results suggest that the feeding pattern of two lines (NL and SY), selected with the same process at two different fish farms, differ. This study addresses the following questions: (i) are the patterns differentially fixed by the selection process and if yes (ii) is this explained by the different genetic background of the lines? In a first experiment, we tested if the group feeding behavior can be inherited. We produced and reared under the same experimental conditions selected hybrids (NLS x SYS) and pure SY selected line (SYS). We compared their behavior on self-feeders when reared single or mixed (groups of 500 fish; mean initial BW = 6 g, 90-day period). Growth rates were comparable among the groups. In the lines reared single, NLS x SYS exhibited greater morning feeding activity than SYS. Feeding activity of SYS was higher later in the day. The inter-day variation of the morning peak was less variable for the hybrid than for the SYS line. In the mixed group, the pattern was intermediate between that of the hybrid and the pure line. In a second experiment we compared the feeding pattern of control hybrids (NLC x SYC) to pure control lines (SYC and NLC) reared single or mixed (groups of 500 fish; mean initial BW = 12 g, 92-day period). Feeding activity patterns were similar among the control groups. These results show that group feeding pattern is a heritable trait that can be indirectly selected with growth, which shape is less influenced by the growth performance and the genetic background than by the environmental conditions applied during the selection process.

Animal models of behavioral dysfunctions: Basic concepts and classifications, and an evaluation strategy

In behavioral neurosciences, such as neurobiology and biopsychology, animal models make it possible to investigate brain-behavior relations, with the aim of gaining insight into normal and abnormal human behavior and its underlying neuronal and neuroendocrinological processes. Different types of animal models of behavioral dysfunctions are reviewed in this article. In order to determine the precise criteria that an animal model should fulfill, experts from different fields must define the desired characteristics of that model at the neuropathologic and behavioral level. The list of characteristics depends on the purpose of the model. The phenotype-abnormal behavior or behavioral dysfunctions-has to be translated into testable measures in animal experiments. It is essential to standardize rearing, housing, and testing conditions, and to evaluate the reliability, validity (primarily predictive and construct validity), and biological or clinical relevance of putative animal models of human behavioral dysfunctions. This evaluation, guided by a systematic strategy, is central to the development of a model. The necessity of animal models and the responsible use of animals in research are discussed briefly.

Artificial selection for increased wheel-running activity in house mice results in decreased body mass at maturity

To test the hypothesis that body size and activity levels are negatively genetically correlated, we conducted an artificial selection experiment for increased voluntary wheel-running activity in house mice (Mus domesticus). Here, we compare body masses of mice from control and selected lines after 14 generations of selection. In both groups, beginning at weaning and then for 8 weeks, we housed half of the individuals with access to running wheels that were free to rotate and the other half with wheels that were locked to prevent rotation. Mice from selected lines were more active than controls at weaning (21 days) and across the experiment (total revolutions during last week: females 2.5-fold higher, males 2.1-fold higher). At weaning, mice from selected and control lines did not differ significantly in body mass. At 79 days of age, mice from selected lines weighed 13.6 % less than mice from control lines, whereas mice with access to free wheels weighed 4.5 % less than ‘sedentary’ individuals; both effects were statistically significant and additive. Within the free-wheel-access group, individual variation in body mass of males was negatively correlated with amount of wheel-running during the last week (P<0.01); for females, the relationship was also negative but not statistically significant (P>0.40). The narrow-sense genetic correlation between wheel-running and body mass after 8 weeks of wheel access was estimated to be −0. 50. A negative genetic correlation could account for the negative relationship between voluntary wheel-running and body mass that has been reported across 13 species of muroid rodents.