Abstract: The major histocompatibility complex (MHC) is a fundamental part of the vertebrate immune system, and the high variability in many MHC genes is thought to play an essential role in recognition of parasites. The Przewalski's horse is extinct in the wild and all the living individuals descend from 13 founders, most of whom were captured around the turn of the century. One of the primary genetic concerns in endangered species is whether they have ample adaptive variation to respond to novel selective factors. In examining 14 Przewalski's horses that are broadly representative of the living animals, we found six different class II DRB major histocompatibility sequences. The sequences showed extensive nonsynonymous variation, concentrated in the putative antigen-binding sites, and little synonymous variation. Individuals had from two to four sequences as determined by single-stranded conformation polymorphism (SSCP) analysis. On the basis of the SSCP data, phylogenetic analysis of the nucleotide sequences, and segregation in a family group, we conclude that four of these sequences are from one gene (although one sequence codes for a nonfunctional allele because it contains a stop codon) and two other sequences are from another gene. The position of the stop codon is at the same amino-acid position as in a closely related sequence from the domestic horse. Because other organisms have extensive variation at homologous loci, the Przewalski's horse may have quite low variation in this important adaptive region. N1 -

Abstract: Methods of ranking individuals in a dominance hierarchy that use transitivity of relationships may obscure irregularities. Furthermore, these methods use only a small proportion of the information available from dominance encounters. This paper presents an intuitively appealing and easily implemented alternative to existing methods for ordering dominance data, developed from the work of Batchelder et al. (1992Journal of Mathematical Psychology36, 185-212). The procedure presented here is based on a mathematical model of paired comparisons and it involves only simple estimation procedures. We illustrate its use with data on dominance among red deerCervus elaphus, stags. The results indicate that dominance relationships are well characterized by the scale values that the model provides, and, because the method provides predictions for all pairings of animals, dominance predictions also exist for pairs of animals that have yet to be observed. Moreover, the dominance outcomes predicted by the model using the order scale are highly correlated with actual dominance observations at all levels. Overall, the procedure described provides a solution to the problem of identifying an appropriate order for a near-linear dominance hierarchy.

Abstract: Behavioural tests using operant conditioning were conducted to examine how miniature pigs discriminate between people. During a 3-week handling period, six 8-week-old pigs were touched and fed raisins as a reward whenever they approached their handler. In subsequent training, the handler and a non-handler wearing dark blue and white coveralls, respectively, and wearing different eau de toilette fragrances sat at each end of a Y-maze. Pigs were rewarded with raisins when they chose the handler. Successful discrimination occurred when the pig chose the handler at least 15 times in 20 trials (P<0.05: by χ2 test). When all pigs exhibited successful discrimination under these standard conditions, they were exposed to Experiments 1 through 4. In Experiment 1, (1) handler and non-handler exchanged colours of coveralls; (2) handler and non-handler exchanged eau de toilette; (3) handler and non-handler exchanged both cues. The non-handler was chosen significantly more often following the exchange of coverall colours and the exchange of both coverall colours and eau de toilette. However, the handler was chosen significantly more frequently following exchange of eau de toilette only. In Experiment 2, when both handler and non-handler wore coveralls of the handler's original colour, the pigs had difficulty discriminating between them. In Experiment 3, both handler and non-handler wore coveralls of new colours. The pigs easily chose the handler wearing red or blue vs. white coveralls. In Experiment 4, (1) two novel people wore coveralls of the original colours of handler and non-handler; (2) the test with the original experimenters was conducted under the original conditions but in a novel place. Between novel people, the one wearing the handler's original colour of coveralls was preferentially chosen by the pigs. The pigs had difficulty discriminating the handler from the non-handler in a novel place. Pigs appear to discriminate between a familiar handler and a non-familiar person based primarily on visual cues, prominent of which is colour of clothing.