Groupe Fitze
Current and Past Mechanisms of Evolution

Interested students are very welcome, and are urged to contact me by email. Please send a letter of interest including a CV written in English, French, Spanish, or German accompanied by recommendation letters. Postdoctoral fellows should attach their three most relevant scientific publications.

The goal of our group is to understand which mechanisms of evolution, both current and past, contribute to observed biodiversity. We also focus on the relative importance of these distinct mechanisms. In studying these topics, we employ multiple approaches combining behavioural ecology, ecology, population dynamics, population genetics, and biogeography.

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

Lacerta vivipara from Formigal                       Psammodromus hispanicus from Madrid

Population dynamics are of fundamental importance in biodiversity and conservation. Each year we survey five natural Common Lizard (Lacerta vivipara) populations located in the Pyrenees. These data allow us to understand how different factors correlate with the observed population dynamics and to calibrate population experiments accordingly.

Since censuses in natural populations do not allow us to distinguish between causes and consequences, we perform population experiments. In these experiments we test which factors affect population dynamics and we investigate their importance in population stability. The oviparous form of the Common Lizard (Lacerta vivipara) is used as a model species. Population experiments are carried out in the Spanish Pyrenees, where we maintain sixteen semi-natural lizard populations. Experimental populations live in a constructed natural habitat, allowing both lizards and their prey to behave normally, without the need for human intervention (e.g. additional food). Population experiments usually run for at least one year. Given that pedigrees are fully known, individual fitness can be measured over several generations. This provides us with almost total control of many of the key factors governing population dynamics.

Experimental semi-natural lizard populations built at our research station in the Pyrenees (Jaca, Spain). From left to right, Miguel Peñalver Alcázar, Luis Martín San José García, Patrick S. Fitze

Sexual selection has been proposed as an important evolutionary force that may impact population stability and lead to speciation. Already Darwin described sexual selection, nevertheless it is still unclear how the intensity of sexual selection is determined and how best to measure it. We are thus interested both in determining sexual selection and in identifying the most appropriate means by which to quantify it. We are also investigating which forms of sexual selection exist in the common lizard, their relative importance and their impact on sexual conflict.

Animals display a wide range of different colours, which may function as signals providing information about health, condition, mating status, etc. To understand why animals display exaggerated coloration, an understanding of the function of coloration and the underlying mechanisms are required. Our investigations of coloration should thus help to provide a link between mechanisms and behaviour. Primarily, we are interested in the mechanisms that determine coloration in both the nestling and adult great tit, and in understanding why yellow plumage is already seen in nestlings. We are also studying the determination and evolutionary history of plumage coloration in Red Warblers (Ergaticus ruber).
Concurrently, a related line of research is devoted to analysis of the colourful ventral coloration of the common lizard Lacerta vivipara. Its ventral coloration ranges from white to orange in the Pyrenees and from yellow to dark orange in the Cévennes (France). Our studies aim to identify the determinant mechanisms underlying these patterns of coloration and the associated implications for sexual selection and population dynamics.

Male colour variation a) in populations from the Cévennes, b) in the Pyrenees and Cantabrian mountains. Note, males from the Pyrenees show patchy coloration on a single scale, while this is not the case in the Cévennes.

Studied species:

Techniques used:
We use a broad range of approaches including experimentation, long-term population studies, population sampling, loads of statistical analyses and sometimes theoretical modelling. Below you will find a short list of the most used techniques

and many more