Evolution of Female Ornamentation: a comparative and experimental approach using island birds

What drives the evolution of female ornamentation?

Explaining the evolution of signals found in nature has been a persistent challenge for biologists, but studies have focused mostly on male ornaments, neglecting the question of why and how these traits evolve in females.

Oceanic islands around the world provide a “natural laboratory” setting to test evolutionary processes due to their simplified ecosystems, and high levels of endemic species with variation in some specific traits.

In particular, island species experience changes in sociality, competition, and predation, all of which are known to influence ornamental traits.

I propose to combine comparative analyses, based on museum data, and detailed experimental investigation in the field, using 3-D printed models, to examine how female (and male) ornaments have evolved in island birds worldwide, while accounting for ancestral mainland attributes.

Specifically, I will investigate a) the social and ecological factors associated with changes in female and male ornamentation following island colonisation, and b) test experimentally how female and male ornamentation elicit predator and competitor responses on both island and mainland settings. The proposed project will thus have three key outcomes.

First, it will determine how the transitions towards increased or decreased ornamentation in both sexes are influenced by changes in social, life-history and environmental factors.

This will address the current disparity in our knowledge of elaborate signals in females vs. males and provide a comprehensive understanding of the processes that promote the diversity of sexual phenotypes.

Second, the project will advance our understanding of the factors shaping the patterns of phenotypic change in island species.

Finally, it will provide the first experimentally test of two central tenets of island ecology, such as lower predation and social competition pressure on islands compared to mainland.