Section 14 — Animal Genetics and Breeding 



merited males won no less than 9 fights per ses- 

 sion and eventually won all 1 1 fights each time. 



Supported by NSF Grant GB-312. 



14.4. Behavioral Effects of Single Genes in Mice: an 

 Investigation with the Use of Ethological 

 Methods. J. H. F. v. Abeelen (Nijmegen, 

 The Netherlands). 



Until now screenings of known genes and 

 their influences on behaviour have been carried 

 out only to a very limited extent. The same holds 

 for the appliance of ethological methods in be- 

 haviour genetics, i.e. the drawing up of 

 ethograms. In the present study a combination 

 of these two approaches was attempted. For 

 this purpose the behaviour of the mice was 

 analyzed in a few tens of behavioral elements 

 that can be seen performed by a solitary male in 

 an observation cage, several special elements by 

 two males placed together, and a number of 

 elements by one male and one female placed 

 together. The screened alleles were: yellow, 

 pink-eyed dilution and jerker. Environmental 

 factors were equalized for all subjects as far as 

 possible. Frequencies of the defined elements 

 performed by mutants were compared with those 

 from non-mutants from the same strains. Also 

 qualitative comparisons were made. 



In spite of the endocrinological effects attribut- 

 ed to the yellow allele no evidence was found for 

 a behavioral effect of this allele. 



Homozygotes for pink-eyed dilution showed 

 significantly less staring at observer and lifting 

 one paw (intention-reconnoitering) and perhaps 

 less reconnoitering also; more grooming and 

 shaking the fur are indicated. Thus these ani- 

 mals show an autistic type of behaviour, probably 

 because of a more or less impaired vision. 

 Other explanations are possible but must remain 

 open at this time. 



Qualitatively the behaviour of the jerkers dif- 

 fered in many respects from normal behaviour. 

 Quantitatively: feeding, fighting and sexual 

 behaviour were disturbed the least, exploratory 

 and comfort behaviour very clearly. 



By the use of ethograms, strain differences 

 may be discovered quickly. Full details will be 

 published in Genetica. 



evolutionary mechanisms of reorganization of 

 the reproductive function in mammals from 

 monoestrousness to polyestrousness. 



It has been shown that the selection of the 

 silver foxes (Vulpes fulvus Desm) kept under 

 farm conditions for mating at the beginning of 

 the breeding season has no effect and cannot 

 change the time and the number of reproductive 

 cycles during the year. The heritability of the 

 mating time in these animals during the breeding 

 season is very low. Nevertheless, some reorga- 

 nization of the reproductive function has taken 

 place in the evolution of domestic animals; the 

 majority of modern forms has lost its monoes- 

 trousness and the strictness of seasonal repro- 

 duction which is characteristic of their ances- 

 tors; they became polyestrous. The causes which 

 called forth such a hereditary reorganization of 

 a stabilized function have not been revealed. 



In our investigation we have shown that in 

 regulation of the reproduction time of foxes the 

 cerebral cortex is implicated. Its properties, in 

 particular, are manifested in the type of the de- 

 fensive behaviour of animals; the foxes with 

 calm type of behaviour mate earlier in the breed- 

 ing season than the aggressive ones and their 

 litter sizes are significantly higher. This correla- 

 tion is not only phenotypical but genotypical as 

 well. The differences in the type of behaviour of 

 animals are based on the genotype and it gives 

 the possibility to select animals according to this 

 character. Ten year's selection carried on by the 

 authors for receiving foxes of calm type of be- 

 haviour called forth in some females the reor- 

 ganization of the reproductive cycle: there were 

 recorded obvious signs of estrus in 4 females out 

 of the breeding season— in September and Oc- 

 tober. During the breeding season (February) 

 these females were mated and gave litters, but 

 their estrus was prolonged up to 18-20 days 

 instead of 5-6 days as it must be usually. In 

 females selected for calm type of behaviour 

 some changes of the fur structure were noted as 

 well. 



The change of a character with law heritability 

 became possible by selecting a correlated charac- 

 ter which regulates the main selected character. 

 The reorganization of the reproductive function 

 realized in the evolution of domestic animals 

 was probably a result of unintentional selection 

 of animals "for domestication". 



14.5. The Ways of Reorganization of the Reproduc- 

 tive Function in Seasonly Reproducing Mam- 

 mals. D. K. Belajev and L. N. Trut (Novosi- 

 birsk, U.S.S.R.). 



This work is devoted to the investigation of the 



14.6. Parity and Mendelian Segregation. L. C. 



Strong and F. N. Johnson (Springville, 

 U.S.A.). 



Luxoid has been reported in several species. 



250 



