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Should I stay or should I go? Immune function as a driver of partial migration

A brown bird is sitting perching on a twig.
The main study species will be Blackbirds.

Billions of animals migrate between breeding and non-breeding areas worldwide, and to move from one environment to another is fundamental for most animals and for ecosystem-functioning. Yet, not all species migrate. But why do some individuals migrate whereas others remain resident? Partial migration, where both migrants and residents coexist within a population, provides an ideal system to study the costs and benefits of migration, and offers the unique opportunity for testing general hypotheses of the causes, consequences and adaptations to residency and migration.

Despite extensive theoretical models about partial migration, the physiological mechanisms that shape partial migration remain poorly understood. My recent work suggests that immune function (which protects the body against diseases and pathogens, but incurs costs) is an important physiological mechanism that may underlie individual decisions to migrate or to remain resident. However, experimental evidence for this mechanism is still elusive. In my current projects on different bird and fish species, I fill this gap by strategically combining the concept of partial migration with measurements of immune function. I aim to test the role of immune function in shaping the decision to migrate or not, i.e. if it is a key mechanism of partial migration.

I am utilising different cutting-edge tracking technologies and combine them with in-depth immunological measurements. Additionally, my collaborator Jesko Partecke at the Max Planck Institute for Ornithology in Germany invited me to use their common garden facilities to disentangle environmental influence from genetic programs.

Questions, I try to answer

  • Are differences in baseline immune function the cause or consequence of partial migration?
  • What are the fitness consequences of differences in immune function and migration/ wintering strategy (migration vs. residency)?
  • Do trade-offs between immune function and migration change when costs of local wintering increase?
  • Is the role of immune function in relation to partial migration dependent on environmental conditions or intrinsic (genetic) programs?

If you are interested in participating in this research (as undergraduate student, PhD-student or PostDoc), please contact me.

A close up on a fish under water.
Similar questions will also be addressed on roach.
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A black bird is perching on a twig.
Why do some individuals stay during winter while others migrate?

Contact information

Arne Hegemann
Evolutionary ecology

Telephone: +46 046-222 37 97
E-mail: arne [dot] hegemann [at] biol [dot] lu [dot] se