Evolution of Reproduction

contact person: J. Tinbergen

 

How should an individual animal maximize its reproductive output? Should it invest all in the current reproduction or should it rather invest in reproductive attempts to come? How should these decisions depend on the environment? And how do animals decide on reproductive investment in an environment that is not predictable. Do these individual decisions affect reproductive success? Answers to these questions are in the core of the field of evolution of reproductive behaviour. Theory predicts that organisms will maximize their fitness, but to what extent is this maximum achieved?

To get the answer on these kinds of questions we study the fate of individual birds in marked populations. Record their reproductive output and describe fitness variations over parameters such as timing and intensity of reproduction, food availability and individual traits. To uncouple possible covariation between traits of individuals (like clutch size or body size) and the environment we manipulate aspects of the reproductive behaviour. In this way a small 'mutation' is mimicked and fitness consequences of variation in such a trait can be quantified.

The success of the offspring is strongly dependent on the probability that the offspring will settle to reproduce. In a natural population success of individuals will therefore depend on what other individuals of the population do. Together with our studies on dispersal ecology we strive towards an integrated approach to unravel how selection shapes reproduction.

 

We study reproductive behaviour and the fitness consequences in two different systems. In one we do experimental manipulation of the brood and clutch size in great tits Parus major in the Lauwersmeer area (northern Netherlands) and in the other we study how social status affects population structure in a non uniform habitat in the oystercatcher Haematopus ostralegus on Schiermonnikoog (Waddensea island).