Abstract: The purpose of this paper is to give a short survey of the present problems concerning the genetic improvement of horse breeds. The evolution of these populations in Europe, characterized by a deep change from production of draught horses towards that of leisure horses, is described and the influence of the demographical parameters on the selection of these horse populations, is discussed. The generation interval represents an important handicap only surmounted in the case of racing breeds where a high selection intensity can be practised since all animals are subjected to performance testing. In the other cases, the farmer usually does not use modern breeding techniques, but uses crosses instead, which lead more easily to visible results. The available selection criteria are also dealt with. A distinction is made between direct estimates evaluating the abilities of the animals in practice and the indirect estimates measuring a character in correlation to previous ones. For the former estimates, a distinction is made between those resulting from competitions (handicap, records or earnings) and those resulting from direct in-station measurements (saddle, jumping, dressage abilities, draught power). For the indirect estimates, often used especially for the selection of mares, the most important analysis is obviously that of the conformation. However, in the future early selection criteria according to more physiological data should be sought and developed. Estimation of the breeding value according to a given ability is thereafter pointed out. There are two situations: “the panmictic case” concerning sport and draught horses and “the non-panmictic case” corresponding to racing horses, which give rise to some problems. The setting up of breeding plans is discussed. Due to the different economic situations and various objectives of horse production, conclusions are drawn about the role played by geneticists in the present development of this sector.

Abstract: 1. Dominance/subordinance is a relationship between two individuals in which one defers to the other in contest situations. Each such relationship represents an adaptive compromise for each individual in which the benefits and costs of giving in or not giving in are compared. Familiar associates in groups or neighbours on nearby territories may develop relatively stable dominant-subordinate relationships based on individual recognition. Although the aggressive aspects of dominance are usually emphasized, the less conspicuous actions of the subordinate individual are actually more important in maintaining a stable relationship. 2. In evolutionary terms, dominance essentially equals priority of access to resources in short supply. Usually the subordinate, who would probably lose in combat anyway, is better off to bide its time until better able to compete at another time or another place. Both individuals save time, energy, and the risk of injury by recognizing and abiding by an established dominant-subordinate relationship. 3. Dominance can be either absolute or predictably reversible in different locations or at different times. Of the various forms of dominance behaviour, rank hierarchies and territoriality represent the two extremes of absolute and relative dominance, respectively. A dominance hierarchy is the sum total of the adaptive compromises made between individuals in an aggregation or organized group. Many animals seem to be capable of both absolute and relative dominance, and within species-specific limits the balance may shift toward one or the other. High density, or a decrease in available resources, favours a shift from relative to absolute dominance. Some species may exhibit both simultaneously. Social mammals may have intra-group hierarchies and reciprocal territoriality between groups, while the males of lek species may exhibit 'polarized territoriality' by defending small individual territories, with the most dominant males holding the central territories where most of the mating takes place. 4. Territoriality is a form of space-related dominance. Most biologists agree that its most important function is to provide the territory holder with an assured supply of critical resources. Territoriality is selected for only when the individual's genetic fitness is increased because its increased access to resources outweighs the time, energy, and injury costs of territorial behaviour. 5. Territoriality was first defined narrowly as an area from which conspecifics are excluded by overt defence or advertisement. The definition has been variously expanded to include all more or less exclusive areas without regard to possible defence, and finally to include all areas in which the owner is dominant. I define territory as a fixed portion of an individual's or group's range in which it has priority of access to one or more critical resources over others who have priority elsewhere or at another time. This priority of access must be achieved through social interaction. 6. My definition excludes dominance over individual space and moving resources, and includes areas of exclusive use maintained by mutual avoidance. It differs from most other definitions in its explicit recognition of time as a territorial parameter and its rejection of exclusivity and overt defence as necessary components of territorial behaviour. There is an indivisible continuum of degrees of trespass onto territories, and functionally it is priority of access to resources that is important rather than exclusive occupancy. 7. There is a similarly indivisible continuum in the intensity of behaviour needed to achieve priority of access to resources. Deciding whether or not an exclusive area is defended leads to the pointless exercise of trying to decide which cues indicating the owner's presence are conspicuous enough to merit being called defence. Concentrating on overt defence emphasizes the aggressive aspects of territorial behaviour rather than the equally or more important submissive aspects such as passive avoidance.

Abstract: Isoluminant stimulus is an image whose edges are defined only by a change in color, not by change in brightness. The stimulus here is imperfect: the blue parts and the green parts of the image are only as nearly equal in brightness as they can be on the printed page. Moreover, the change in brightness beyond the edge of the page is apparent, and so is the fact that the reader is holding the magazine at reading distance. When such cues are removed under laboratory conditions, subjects faced with an isoluminant stimulus prove unable to bring its edges into focus. This deficiency contributes to making a familiar face hard to recognize. The experiment indicates that the brain process underlying visual accommodation (the focusing of the eyes) cannot “see” color; it is a hidden process distinct from the processes that lead to perception. The image shows Groucho Marx as he appeared in the motion picture Horse Feathers.

Abstract: Determined behavioral audiograms for 3 horses and 2 cows. Horses' hearing ranged from 55 Hz to 33.3 kHz, with a region of best sensitivity from 1 to 16 kHz. Cattle hearing ranged from 23 Hz to 35 kHz, with a well-defined point of best sensitivity at 8 kHz. Of the 2 species, cattle proved to have more acute hearing, with a lowest threshold of –21 db (re 20 μN/m–2) compared with the horses' lowest threshold of 7 db. Comparative analysis of the hearing abilities of these 2 species with those of other mammals provides further support for the relation between interaural distance and high-frequency hearing and between high- and low-frequency hearing. (39 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)

Abstract: Hearst and Jenkins proposed in 1974 that elicited responding accounts for the feature-positive effect. To test this position, pigeons were exposed to a feature-positive or feature-negative discrimination between successively presented displays--one consisted of a red and a green response key and the other consisted of two green response keys. There were four main conditions: 5-5 (5-sec trials, 5-sec intertrial intervals), 5-30, 30-30, and 30-180. Conditions 5-30 and 30-180 should produce the largest amount of elicited responding, and therefore the largest feature-positive effects. A response-independent bird was yoked to each response-dependent bird to allow direct assessment of the amount of elicited responding generated by each condition. Contrary to the predictions by Hearst and Jenkins's theory, response-dependent birds showed large feature-positive effects in each condition. The largest feature-positive effect was obtained in condition 5-5. Response-independent birds produced similar results, but manifested low response rates.