Conserving threatened species
Over the past few decades, extinction rates have been elevated to 2-3 orders of magnitude above the background level. Many more species are on the verge of extinction, due to small population sizes or highly restricted ranges. Understanding the ecology, evolution and behaviour of such threatened species is essential for informing conservation. We focus on Afrotropical and Palearctic raptors and the tropical Seychelles warblers.
Ecology and conservation of Palearctic and Afrotropical raptors
Many populations of raptors in West Africa have dramatically decreased since the 1970s, but evidence on the processes involved is scarce and largely anecdotal. Subtle effects of land degradation have pronounced effects on food quality and nestling growth, which may constrain survival and long-term population viability. Vulnerability to land use change is further affected by species (body size), sex- and age-related factors, which determine foraging strategies and diets; sedentary raptors are generally more vulnerable to land use change in West Africa than migratory raptors wintering in Africa. Apart from factors operating on winter grounds, survival and reproduction of migratory raptors may also be affected by changing conditions en route to winter grounds. To examine such effects, the red-listed Montagu’s harrier, a long-distance migratory raptor, is being studied. Satellite data revealed that individual Montagu’s harriers were site-faithful and occupied distinct home ranges on winter grounds. These home ranges tracked seasonal changes in food availability related to rainfall patterns. These satellite studies highlight the importance of conditions outside breeding grounds on the viability of populations of migratory species.
Genetics, fitness and conservation of the Seychelles warbler
The Seychelles warbler is a prime example of how science and conservation can work hand-in-hand. In the 1960s this species was reduced to just 29 individuals on a single island. Thanks to subsequent conservation efforts the population has now increased to carrying capacity of ca. 320 individuals, and four translocations to new islands have been carried out. Three projects aim to improve our understanding of both the role and maintenance of functional variation in wild populations and to provide novel information for conservation projects.
In the first project, we examine variation at major histocompatibility complex (MHC) genes, which code for key immune molecules. This, combined with microsatellite and life-history data, allows us to investigate patterns of genetic variation across space and time and link this to fitness traits. The MHC research has a strong conservation context, and investigates the effects of conservation action, particularly translocations, on adaptive variation.
In the second project, functional variation at other known immune loci is examined (e.g. toll-like receptors and beta-defensins). We explore parasite-mediated selection as a driver of evolutionary and demographic patterns in the warbler system. This not only helps to infer the genetic health of this severely bottlenecked species, but can also be incorporated into its effective conservation management.
Finally, genome-wide diversity in the Seychelles warbler source population will be quantified to identify the genes important for historical adaptation and contemporary fitness. We will quantify how this diversity has been lost in the small translocated Seychelles warbler populations. The results will be used to inform translocation policy, and will directly impact on endangered species conservation.
- Genomic approaches to conserving translocated populations
- Importance of stopover- and wintering sites for conserving threatened long-distance migrants
- The effect of land transformation on a West-African raptor community
- Beyond the MHC: Consequences of functional variation at immune loci in the Seychelles warbler
- Evolutionary and conservation genetics in the Seychelles warbler - MHC diversity
Buij R., Folkertsma I., Kortekaas K., de Iongh H.H. & Komdeur J. (2012): Effects of land use change in Sudano-Sahelian West Africa on the diet and growth of an avian predator. Ibis, in press.
Buij R., Van der Goes D., De Iongh H., Gagare S. Haccou P., Komdeur J. & De Snoo G. (2012): Implications of land-use change for three Palearctic harriers on the core Sahelian wintering grounds. Ibis, in press.
Trierweiler C., Mullié W., Drent R., Exo K.-M., Komdeur J., Bairlein F., Harouna A., Bakker M. & Koks B. (2012): A Palaearctic migratory raptor species tracks shifting prey availability within its wintering range in the Sahel. J. Anim. Ecol., in press.
Spurgin L.G., van Oosterhout C., Illera J.C., Bridgett S., Gharbi K., Emerson B.C. & Richardson D.S. (2011): Gene conversion rapidly generates MHC diversity in recently founded bird populations. Mol. Ecol. 20, 5213-5225.
Spurgin L.G. & Richardson D.S. (2010): How pathogens drive genetic diversity: MHC, mechanisms and misunderstandings. Proc. R. Soc. Lond. B 277, 979-988.
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