How bird communities evolve and spread

The BIRDEVOBIOGEO (Passerine bird evolution and biogeography) project focused on a large group of passerine (perching) birds known as the Corvoidea, which comprises the crow family. The Corvoidea originated in the mid-Tertiary in Australia, before spreading across the Indo-Pacific archipelagos onwards to other continents.

At present, molecular data exists for about 85 % of Corvoidea species, thereby enabling evolutionary and biogeographical theories to be tested using evolutionary and ecological statistical tools. These theories concern the history of this group and the reasons behind their success and offer hope in answering questions regarding diversity, evolution, community assembly and biogeography.

Using passerine bird species from the tropical regions of Africa and Asia, BIRDEVOBIOGEO showed that the build-up of continental passerine communities is continuously influenced by random extinction of entire clades. A clade is a group that shares inherited features from a common ancestor.

Data based on the morphology of more than 5 000 passerine bird species revealed that different groups tend to occupy the same morphological space. Morphological space acted as a proxy for what the birds ate and in which habitat they lived.

It was also revealed that passerine birds occupy a wide range of niches and potentially interact, but this has little to do with the relative order of colonisation. Other significant results indicated that seasonal migration has facilitated diversification through the divergence of migratory subpopulations that have become sedentary.

BIRDEVOBIOGEO generated valuable new data on how communities of birds form and which spatial and temporal factors affect the build-up of both continental and island bird communities.