Project
The ecological and evolutionary consequences of hybridisation in birds
My main research lines focuses on the genetic consequences of hybridisation, the interbreeding of different species. How do species remain distinct despite (extensive) hybridisation? Which genomic regions contribute to reproductive barriers between species, and which genomic regions can freely flow (i.e. introgress) across species boundaries?
Description
I have been studying the evolutionary history of the True Geese (Anseriformes, Anatidae, Anserinae), a group of birds with a high incidence of hybridisation. Reconstructing the phylogeny of the geese using genomic data revealed two main groups that correspond to the genera Anser and Branta. More detailed analyses uncovered high levels of introgression between several species. The evolution of geese can thus be better represented by a network than a phylogenetic tree. However, the complex introgression patterns made it difficult to pinpoint the exact timing of hybridization events. Therefore, I focused on particular (sub)species, such as the Bean Goose complex: Taiga Bean Goose (Anser fabalis), Tundra Bean Goose (Anser serrirostris) and the Pink-footed Goose (Anser brachyrhynchus). Phylogenomic analyses of these three taxa revealed that the Pink-footed Goose is sister to the Taiga Bean Goose, with the Tundra Bean sister to both taxa. This evolutionary pattern has been complicated by gene flow between Taiga and Tundra Bean Goose. Model-based analyses revealed that these taxa diverged about 2.5 million years ago and exchanged genetic material ca. 60,000 years ago.
Apart from my goose research, I am also interested in avian hybridisation in general. Therefore, I started the Avian Hybrids Project, a website gathering the scientific literature on hybridisation in birds. This project was announced with a publication in the ornithological journal Ibis where I also quantified the incidence of hybridisation in birds. In total, 1714 out of 10 446 bird species (16.4%) have been documented to have hybridised with at least one other bird species in nature. When hybridisation in captivity is included, this figure increases to 2204 species (21.1%). I also introduced a scoring scheme to assess the evidence of hybrid records and I applied this scheme to tinamous. It is important to note that hybridisation is not always limited to two species, often multiple species are interbreeding.
Hybridisation is thus an integral part of the evolution of many (bird) species. It can lead to exchange of genetic material between species and give rise to new species through homoploid hybrid speciation. These insights also have consequences for the way we study evolutionary and ecological questions, such as the use of phylogenetic networks and the application of species concepts in taxonomy.
Publications
- Ottenburghs, J., Ydenberg, R.C., van Hooft, P., Van Wieren, S.E., & Prins, H.H.T. (2015). The Avian Hybrids Project: gathering the scientific literature on avian hybridization. Ibis, 157(4), 892-894.7(4), 892-894.
- Ottenburghs, J., Megens, H.-J., Kraus, R.H.S., van Hooft, P., van Wieren, S.E., Crooijmans, R.P.M.A., Ydenberg, R.C., Groenen, M.A.M. & Prins, H.H.T. (2017). A History of Hybrids? Genomic Patterns of Introgression in the True Geese. BMC Evolutionary Biology. 17:201.
- Ottenburghs, J. (2019) Multispecies Hybridization in Birds. Avian Research, 10:20.
- Ottenburghs, J. (2021) The genic view of hybridization in the Anthropocene. Evolutionary Applications. 14(10): 2342-2360.
- Ottenburghs, J., Honka, J., Heikkinen, M.E., Madsen, J., Müskens, G. & Ellegren, E. (2023) Highly Differentiated Loci Resolve Phylogenetic Relationships in the Bean Goose Complex. BMC Ecology and Evolution. 23(2).