Download RESEARCH INTEREST The frame work It is well known that within

RESEARCH INTEREST
The frame work
It is well known that within species consistent differences in behaviour among individuals exist, and
nowadays, personalities are recently recognized in many animal species. This individual variation in
behaviour is intriguing, since in its simple form directional evolutionary selection for the best adapted
individual should eliminate such variation. An obvious possibility is that the origin of individual
differences lies in early ontogeny. Notwithstanding the great importance of genetic variation,
environmental factors appear to exert an influence on behavioural development that is often much
more important and subtle than assumed. Therefore, studying behavioural development is important,
because it yields insight into the flexibility of developmental trajectories, and in the mechanisms and
function of (pathologies) in adult behaviour. Clearly, individual variation in behaviour is not just
noise but can reveal important biological variation.
Development starts already in utero or in the egg. The importance of prenatal factors on
development has long been underestimated (out of sight, out of mind) but is now increasingly
acknowledged as having important organizing effects on brain and behaviour. One of these factors are
steroid hormones.
In many animal taxa, embryos are not only exposed to hormones that they produce themselves,
but also to hormones from their mother. This is intriguing, since it is well known that prenatal
exposure to steroid hormones can have profound long time organizing effects on the phenotype, such
as on sexual differentiation. The embryonic exposure to maternal hormones is, at least partly, a
function of the hormonal status of the mother, which is in turn depending on environmental
conditions. This opens the fascinating possibility that mothers translate the environmental conditions
to their young via the transfer of their hormones. In this way the mother can anticipate the conditions
in which the young will be reared, and adjust their development accordingly. The transfer of maternal
hormones to the embryo is a form of non-genetic inheritance that provides the mother with a flexible
tool to maximize her Darwinian fitness, in addition to genetic inheritance. These hormone mediated
maternal effects are currently an important line of my research.
We study the effects of the interplay between environment and hormones on early development
both in the prenatal and the early postnatal phase. We focus not only on the development of
personality, but also on lateralization of brain and behaviour. This lateralization, in which each of
the hemispheres of the brain is specialized for certain tasks, is a fundamental aspect of the
organization of brain and behaviour in vertebrates, affecting perception, emotion, cognition and motor
behaviour. Our work has also applied aspects, for example for improving animal welfare in the
commercial animal breeding industry, where housing conditions in one generation may affect later
generations but such maternal effects are as yet hardly addressed.
The field of developmental behavioural endocrinology is an excellent field for integrating
mechanistic and functional / evolutionary approaches. Over the past thirty years, the physiological
and ecological approaches to behaviour have grown apart. It is my belief that for progress in both
fields these two different approaches should be integrated. For the understanding of the function and
evolution of behaviour we need to understand the physiological regulation mechanisms that underlie
behaviour, in order to understand how flexible the phenotype is, and where evolutionary selection can
act or is constrained. Vice versa, the study of causal mechanisms of behaviour should be inspired by
knowledge of which problems are faced by the animal in the natural condition, and how these should
be solved in order to increase its survival and reproductive success.
This integration requires integration of lab and field studies. In addition, I am convinced that the
use of a diversity of animal models, in addition to the laboratory mouse or rat, can yield important
new insights into the regulation and function of behaviour. The study of hormone-mediated maternal
effects provides excellent opportunities for such approaches. These effects exist in a wide array of
animal taxa, and we use both fish, birds and mammals, including humans. It concerns the study of
physiological mechanisms within a clear functional and evolutionary context. Furthermore, hormones
have many pleiotrophic effects, and are probably important regulators of so called trade-off’s, a key
concept in evolutionary biology. Therefore my collaborations span the wide array from
neuroendocrinologists to behavioural ecologists.
Experimental testing of hypotheses, generated by descriptive studies under natural conditions, is
indispensable for scientific progress. To test experimentally the effect of prenatal exposure to
maternal steroids on development, avian species are much more suitable than mammalian species,
since in the former the embryo develops outside the mother’s body, easy assessable for measurement
and manipulation. In addition, avian species are classical models for the study of behavioural ecology,
and well suited for developmental studies under artificial conditions because of the possibility to rear
the animals by hand. This renders these species ideal to integrate mechanistic (proximate) and
functional/evolutionary (ultimate) approached to behavioural development.
We recently moved to a new building with state of the art facilities: almost 150 modern
outdoor aviaries for birds and rodents and of different sizes, including very large ones; indoor
facilities for keeping a wide array of species, climate rooms, surgery rooms, endocrinology and DNA
labs etc. (see the website of the group and the institute). A large crew of animal caretakers is
available, as well as several lab technicians