How genetic constraint and selection drive colour diversification? Reconstructing the evolutionary history of sexual dichromatism in island endemic lizards

How genetic architecture and selection jointly contribute to evolution is central to understanding the striking diversity of colours and patterns in nature. Yet, major questions remain: do novel colour variants appear gradually or in jumps? Can evolution of sexual signals proceed independently of colours used for crypsis?

Can evolution modify male colouration independently of the colour of females and vice versa?

Answering these questions requires the integration of highly multivariate data on colouration and ecological data, as well as information about the underlying genetic relatedness between populations and lineages.

In particular, rapid diversification of coloration, between lineages of the same species, can put the role of genetic constraint and selection in evolution to the test.

This project will be novel in studying these factors simultaneously across an extraordinary radiation: Balearic wall lizards (Podarcis pityusensis and Podarcis lilfordi).

These lizards exhibit a striking variation in colouration between lineages isolated on more than forty islands in the Balearic Islands (Spain).

In this project, I will i) reveal the evolutionary history of Balearic wall lizards, ii) establish if genetic constraints bias evolutionary change by reconstructing evolutionary transitions in body colouration between males and females (i.e. sexual dichromatism), and iii) put to the test the role of sexual and natural selection for evolutionary change in male and female colouration.

This will offer genuine insights into the origin and evolution of colour diversity, and help to resolve how the diversification of colouration is shaped by genetic constraints and sexual and natural selection.

Complementary, this project will provide a wealth of information (e.g. molecular, morphological, ecological) about two endemic species currently facing a decreasing population trend.