Domestication Effects in the Domestic Dog
The domestic dog have trough artificial selection changed and today shows a great varity of behavioural and morphological traits. Despite these breed specific traits the selection towards breeds suitable for societal needs may have narrowed these variances and shaped dogs that are more and more similar decreasing the importance of breed specific traits.
According to archaeological evidences the dog was the first animal to be domesticated (Morey, 1994) and its East Asian (EA) origin has been well establish from genetic data (Savolainen et al, 2002). It is said to be the animal that in shortest time achieved the largest diversity in the animal kingdom (Coppinger & Schneider, 1995). To reveal the effects of domestication two breed groups were compared; EA, presumably more primitive, and West European (WE) breeds, presumably more domesticated. The selection of the five EA breeds were based on genetic analyses that have shown that these breeds possess larger genetic variation than other breeds (Savolainen et al, 2002). The eleven WE breeds were selected by creating a new top list out from the top registration list from the western part of Europe and America.
The behavioural part was carried out with help of the Dog Mentality Assessment (DMA) developed by the Swedish Working Dog Association (SWAD). In earlier analyses of the DMA its variables have been found to correlate and create five behavioural dimensions (Svartberg & Forkman, 2002). As a compliment nine basically measurements of relationships and angles in the different breeds’ morphology were compared. The overall prediction was that there would be both behavioral and morphological differences between the groups.
When looking at the overall behavioural results from the DMA the breed groups differed in several sub tests. Further factor analysis showed that the two groups had only two behaviour dimensions in common; “Play” and “Chase”. Factor loading “Play” showed that the the WE breeds played significantly more (p=0.005). There were no differences between them in “Chase”, but the EA breeds showed a larger variation in responses compared to the WE. Factor analyses seperately showed that the two breed groups showed different behavioural dimensions.
The morphological comparison showed that there was a conformity within the WE breed group compared to the larger variation showed in the EA breed group. These results suggests that although modern breeds show an enormous variety in both morphological traits and breed specific behaviour, selection towards breeds suitable for societal needs may have narrowed these variances and shaped dogs that are more and more similar. The narrow variation within the WE compared to the larger variation found within the EA in both the DMA as well as in morphological traits supports this conclusion. The results suggest that domestication has lead to more playful, dependent, and morphologically similar breeds, decreasing the importance of breed specific traits.
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Svartberg K. & Forkman B. (2002) Appl. Anim. Behav. Sci. 79, 133-155.