In my current research I try to bridge the gap that exists between the evolutionary predictions based on theory and experimental laboratory studies using genetic model organisms on the one hand, and the results from the often correlative work that has been done in natural populations of birds and mammals on the other.using the Australian field cricket (Teleogryllus commodus) as a model system. Field cricket provides us in many ways with an ideal study system. Not only are we able to breed large numbers of field-collected individuals in captivity under highly controlled conditions and following established protocols, we can also study them in their natural habitat. Interestingly, a recent common-garden experiment involving crickets from across Australia revealed large genetic differences among populations with respect to important fitness-traits like clutch size and calling effort (Hunt, Bussière, Jennions and Brooks, in prep.).

 

I recently obtained a discovery grant from the Australian Research Council (ARC) to perform an in-depth investigation of the genetic differentiation on the one hand, and the patterns of selection driving this differentiation on the other. In this project I am working together closely with Will Pitchers and John Hunt at the Centre for Ecology and Conservation  of the University of Exeter.

Vlieland is one of the smaller islands in the Dutch part of the Wadden Sea (53.17ºN, 5.03ºE, 3258 ha). The population consists of five more or less spatially separated woodlands (total surface ca 300 ha) and a small village. The landscape between the woodlands consists mainly of dunes and is unsuitable habitat for great tits.

Since nest boxes are available in excess in all suitable nesting habitat, it is possible to monitor the complete population and to ring all chicks that are born on the island each year. As a result of the isolated nature of the population, immigration rates are relatively low, whereas local recruitment rates are high. This makes it possible to reconstruct individual pedigrees in great detail, and to obtain relatively accurate fitness measures for all individuals. These characteristics make Vlieland exceptionally suitable for a study into the evolutionary genetic of wild populations.

My research has greatly benefited from a three month stay at the University of Edinburgh (funded by a Marie Curie training fellowship of the European Union), where I had the opportunity to acquaint myself with the application of animal model methodology to data from natural populations of known pedigree.

The animal model is a specific form of mixed model, originally developed by animal breeders to identify individuals of high genetic merit. In contrast to the more traditional quantitative genetics methods, these methods use all the information that is available in a pedigree, and do not require a specific pedigree structure. Furthermore they are able to accommodate selection and inbreeding, which are common phenomena in the great majority of natural populations.

 

The animal model may help to answer two types of questions, both of which are central to the study of evolution. On a population level it provides a method to separate the phenotypic variance we observe in the field into the underlying genetic and environmental variances and covariances, and thus for estimating heritabilities and genetic correlations. Second, and more excitingly, it makes it possible to separate environmental and genetic effects on both an individual and a population level. More specifically, it allows for the quantification of the sum of the additive effects of an individual's genes for a given trait, and thus the expected effect of the genes that it passes on to its offspring, also referred to as its 'breeding value'.