Abstract: Dressage is one of the Olympic equestrian sports practiced in several countries using different horse breeds. Specific characteristics of the walk, trot and canter are required for dressage. It has been assumed that some of these traits could be selected for genetically and contribute to dressage performance. The purpose of this study was to compare the walk, trot and conformation characteristics in young horses of different breeds used for dressage. A total of 142 horses age 3 years were classified into 3 groups of breeds (German, French and Spanish saddle horses) and tested using the same procedure. The skeletal conformation measurements were made by image analysis. Gait variables of the walk and trot were measured by the accelerometric gait analysis system Equimetrix. Discriminant analysis could explain the variability between the groups by taking into account the walk (P<0.0003), trot (P<0.0001) and conformation variables (P<0.0001). Many gait and conformation variables were significantly different between the breeds. In summary, the German horses had gait characteristics more adapted for dressage competition, and the results of this group could be used as a reference for early evaluation in dressage. Purebred Spanish horses could be considered as a reference for collected gaits used for farm work and old academic dressage. The gait and conformation tests could be applied in a breeding or crossing plan to detect more accurately young horses with good dressage ability.

Abstract: Criteria used to measure performance, environmental factors that influence performance and estimates of heritability are needed to estimate genetic differences. Published heritability estimates of various measures of performance in the horse are summarized. The average heritability estimates of pulling ability and cutting ability are .25 and .04, respectively. Heritability estimates are .18, .19 and .17 for log of earnings from jumping, 3-day event and dressage performance, respectively. Heritability estimates of performance rates, log of earnings, earnings, handicap weight, best handicap weight, time and best time for the Thoroughbred are .55, .49, .09, .49, .33, .15 and .23, respectively. Heritability estimates of log of earnings, earnings, time and best time for the trotter are .41, .20, .32, and .25, respectively. The heritability estimate of best time for the pacer is .23. The effectiveness of selection will depend on which performance trait is to be improved.

Abstract: A comprehensive evolutionary framework for understanding the maintenance of heritable behavioral variation in humans is yet to be developed. Some evolutionary psychologists have argued that heritable variation will not be found in important, fitness-relevant characteristics because of the winnowing effect of natural selection. This article propounds the opposite view. Heritable variation is ubiquitous in all species, and there are a number of frameworks for understanding its persistence. The author argues that each of the Big Five dimensions of human personality can be seen as the result of a trade-off between different fitness costs and benefits. As there is no unconditionally optimal value of these trade-offs, it is to be expected that genetic diversity will be retained in the population.

Abstract: There is abundant evidence, some of it reviewed in this paper, that personality traits are substantially influenced by the genes. Much remains to be understood about how and why this is the case. We argue that placing the behavior genetics of personality in the context of epidemiology, evolutionary psychology, and neighboring psychological domains such as interests and attitudes should help lead to new insights. We suggest that important methodological advances, such as measuring traits from multiple viewpoints, using large samples, and analyzing data by modern multivariate techniques, have already led to major changes in our view of such perennial puzzles as the role of “unshared environment” in personality. In the long run, but not yet, approaches via molecular genetics and brain physiology may also make decisive contributions to understanding the heritability of personality traits. We conclude that the behavior genetics of personality is alive and flourishing but that there remains ample scope for new growth and that much social science research is seriously compromised if it does not incorporate genetic variation in its explanatory models.

Abstract: The oft-repeated concern for the lack of behavioral comparability of domestic rats with wild forms of Rattus norvegicus is unfounded. Laboratory rats appear to show the potential for all wild-type behaviors, including the most dramatic social postures. Moreover, domestics are capable of assuming a feral existence without difficulty, one where they readily behave in a fashion indistinguishable from wild rats. The one behavioral difference that is clearly established concerns performance in laboratory learning paradigms. The superiority of domestics in these laboratory tasks speaks more to quieting the concerns of degeneracy theorists than to problems of using domestic Norway rats as subjects representative of their species.