Relations pondérales entre l’encéphale et le corps chez les chiroptères. II. Espèces paléo-tropicales et paléarctiques. Discussion et conclusions
Bijdragen tot de dierkunde , Volume 40 - Issue 2 p. 103- 115
The ratio brain weight/body weight is studied in 30 species of bats from Asia, Africa and Europe, in comparison with 20 other species from South America dealt with in a previous paper. The simple encephalic ratios, expressed in o/oo, vary considerably and about between the same limits on the four continents. Further, logarithmic regression lines (brain to body), when fitted to the representatives of various dietary types, provide slope and ordinate values that are visually distinguishable. Besides, the encephalic ratios themselves show, among bats, a negative correlation with the abolute somatic weight, as one might have expected. But, if one compares graphically, from that viewpoint, the Chiroptera on the one hand with a number of Insectivores and Primates on the other hand, one can observe that the first order is situated in an intermediary zone between the other two. A number of encephalic ratios for insect-eating bats are nevertheless intermingled with those for Insectivores; finally, some of the bats show clearly higher ratio-values than the others and those bats belong to ethologically specialized species (always from the viewpoint of the diet). Similarly high values of the encephalic ratio are also found amoung Primates, especially in man. This leads to the hypothesis that, at the origin of certain phyletic branchings, an increase of the encephalic nervous mass may take place (perhaps before any other size progress can occur). Such an increase would immediately constitute a selective advantage. However, the problem cannot be reduced to a mere increase in weight of the total brain until the details of cerebral structures have been studied in various groups so that the evolution of each part of the brain, in relation with particular needs for sensory controls, is better known.
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Pirlot, P. (1970). Relations pondérales entre l’encéphale et le corps chez les chiroptères. II. Espèces paléo-tropicales et paléarctiques. Discussion et conclusions. Bijdragen tot de dierkunde, 40(2), 103–115.