Behaviour genetics in the post-genomics era: From genes to behaviour and vice versa

摘要

Approaches to understanding behaviour in an evolutionary context can be grouped into two broad categories: behaviour genetics and behavioural ecology. In this paper, I briefly discuss the development of these two fields, to highlight some serious shortcomings in their focus and/or approach to understanding behaviour. These shortcomings have been pointed out by numerous researchers before, but it seems to be an opportune time to revisit this issue because present day methods are making it increasingly likely that some of these gaps in our understanding of behaviour can now be addressed experimentally. Early behaviour genetics essentially led to neurogenetics due to its focus on single-gene mutations affecting behaviour, which were often mutations affecting the nervous system. This line of work, consequently, diverged considerably from the study of behaviour per se and, although it contributed a great deal to our understanding of how the components of the nervous system work, it did not really shed much light on behaviour at the organismal level. More recent approaches in behaviour genetics include quantitative trait loci (QTL) mapping, which is an attempt to go beyond the black box approach of classical quantitative genetics and to track down loci mediating behavioural differences among individuals. Behavioural ecology provided a counter point to traditional behaviour genetics by explicitly focusing on ultimate causes, and trying to understand behaviour in terms of its adaptive (fitness) value. However, behavioural ecology too has at its core a conceptual lacuna, which is the absence of knowledge of the genotype-to-phenotype mapping for most behavioural traits. This conceptual lacuna is serious, and it affects not just behavioural ecology but most attempts to understand the evolutionary dynamics of complex and composite phenotypes that are, in terms of gene expression, far removed from the genome. What I have to say, therefore, applies broadly to attempts to understand the evolutionary shaping of complex phenotypes, and not just to studies of behaviour. I suggest that we really need a new and enlarged conception of, and approach to, behaviour genetics; an approach that will utilize recent advances in genetic technology, but yet be rooted in a holistic, organismal weltanschaung. I briefly describe some examples of this approach that I believe highlight the potential that this new behaviour genetics has to enrich and round off our understanding of behaviour from an evolutionary perspective.