Captivity

Abstract: As wild environments are often inhospitable, many species have to be captive-bred to save them from extinction. In captivity, species adapt genetically to the captive environment and these genetic adaptations are overwhelmingly deleterious when populations are returned to wild environments. I review empirical evidence on (i) the genetic basis of adaptive changes in captivity, (ii) factors affecting the extent of genetic adaptation to captivity, and (iii) means for minimizing its deleterious impacts. Genetic adaptation to captivity is primarily due to rare alleles that in the wild were deleterious and partially recessive. The extent of adaptation to captivity depends upon selection intensity, genetic diversity, effective population size and number of generation in captivity, as predicted by quantitative genetic theory. Minimizing generations in captivity provides a highly effective means for minimizing genetic adaptation to captivity, but is not a practical option for most animal species. Population fragmentation and crossing replicate captive populations provide practical means for minimizing the deleterious effects of genetic adaptation to captivity upon populations reintroduced into the wild. Surprisingly, equalization of family sizes reduces the rate of genetic adaptation, but not the deleterious impacts upon reintroduced populations. Genetic adaptation to captivity is expected to have major effects on reintroduction success for species that have spent many generations in captivity. This issue deserves a much higher priority than it is currently receiving.

Abstract: Behaviour under conditions of mild stress shows consistent patterns in all vertebrates: exploratory behaviour, boldness, aggressiveness covary in the same way. The existence of highly consistent individual variation in these behavioural strategies, also referred to as personalities or coping styles, allows us to measure the behaviour under standardized conditions on birds bred in captivity, link the standardized measurements to the behaviour under natural conditions and measure natural selection in the field. We have bred the great tit ( Parus major ), a classical model species for the study of behaviour under natural conditions, in captivity. Here, we report a realized heritability of 54±5% for early exploratory behaviour, based on four generations of bi-directional artificial selection. In addition to this, we measured hand–reared juveniles and their wild–caught parents in the laboratory. The heritability found in the mid–offspring–mid–parent regression was significantly different from zero. We have thus established the presence of considerable amounts of genetic variation for personality types in a wild bird.