Some Remarks on Bird's Brain and Behavior under the Constraints of Domestication

Julia Mehlhorn,Gerd Rehkämper

doi:10.5402/2013/460580

Abstract

The relationship between domestication and evolution is still a matter of discussion. In this review, we present some arguments for the assumption that domestication could be seen as an evolutionary process including the possibility that new species might evolve. In course of domestication, many breeds have been developed which show numerous alterations in different parameters such as body size, coloring, habitat, behavior, and brain size and composition. Here, we would like to give an overview particularly about alterations and varieties in (brain) morphology and behavior in domestic poultry and argue that these alterations could be seen as adaptations to the man-made environment.

Highlights

Domestication of animals is a recent event in human history and is defined as that condition wherein the breeding, care, and feeding of animals are more or less controlled by man [1]
By showing that mate choice of the breeder interacts with mate choices made by the animals itself, this argument is weakened [7]
The second argument is that there is still sexual attractiveness between the breeds of a domestic species and its wild ancestors [8]. This is not in line with the biological species concept according to which species are freely interbreeding groups of individuals living in reproductive isolation from other groups of this kind. This argument neglects the phenomenon of hybridization and that it is more important to determine which genetic pairing is seen more often statistically and if there are nonrandom mating patterns [12]

Summary

Introduction

Domestication of animals is a recent event in human history and is defined as that condition wherein the breeding, care, and feeding of animals are more or less controlled by man [1]. Empirical data on brain sizes which show smaller brains in dogs than in wolves or in domestic ducks in comparison to mallards seem to support this point of view [13, 14] To this “regression hypothesis” stands the “adaptation hypothesis” (e.g., [15,16,17]) which means that domestication is a dynamic evolutionary process and that all alterations during domestication are of adaptive character and due to changed conditions of a man-made environment. Among the population of domesticated animals it is generally differentiated between economical strains and strains which are bred just for the pleasure of their breeder The latter, the so-called fancy breeds, mostly do not perform high production of meat, milk, wool, eggs, or feathers but show as well numerous differences in comparison to their wild ancestors. It will give some support to (a) the adaptation hypothesis of domestication and (b) the idea that under domestication new species might evolve

Domestication of Birds

Alterations in Brain and Behavior

Summarizing Remarks