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Fitze Lab

Research lines

Animals display a wide range of different colours, which may function as honest signals providing information about health, condition, mating status, etc. To understand why animals show exaggerated coloration, knowledge about the mechanisms that determine coloration and about the function of the coloration is needed. Investigating coloration should thus link mechanisms with behaviour. We are interested in the mechanisms that determine the coloration of nestling and adult great tits and in why they display yellow plumage feathers already as nestlings.




At the same time we are investigating why common lizards Lacerta vivipara show a colourful ventral coloration. Its ventral coloration ranges from white to orange colours in the Pyrenees and from yellow to dark orange colours in the Cévennes (France). We are interested in the determinants of this coloration and its implications for sexual selection and population dynamics.




Sexual conflict
Sexual conflict over mating decisions may lead to the evolution of male- and female-specific mating strategies. While it is generally accepted that copulating with many females leads to increased male fitness, it is less obvious why females copulate with several males. Sex specific reproductive strategies may translate into sex specific life histories, which then may directly affect population dynamics. In the polygynandrous common lizard Lacerta vivipara we are investigating the mating behaviour of both males and females, how the strength of the sexual conflict affects mating decisions, and whether sexual conflict affects population dynamics.


Dispersal and population dynamics
One of the first major decisions offspring are faced with, is the decision over staying where they were born, or dispersing. Which sex disperses, and the reasons of dispersal may be very diverse. Some patterns may however be constant in time (e.g. female offspring are more likely to disperse), while others might be context-dependent. We are mainly interested in why some but not all individuals disperse, in the associated costs or benefits, and in how dispersal affects population dynamics. For this purpose we are working with common lizards Lacerta vivipara where we run experiments on the population level.


Current and past evolution of animal populations

We are investigating the evolutionary mechanisms that led to the current genetic, morphologic, phenotypic, and behavioural variability. We integrate behavioural data, genetic data, morphometric measures, ecological niche data, and geological data. More specifically, we are principally interested in the relative contribution of the different types of evolution (e.g. ecological patterns, allopatric speciation,...) to the observed variability. Our study organisms are the Spanish Sandracer (Psammodromus hispanicus), the Common Lizard (Lacerta vivipara), and several bird species.