STAY OR GO

Partial migration: individual causes and population genetic consequences

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 Obiettivo del progetto (Objective)

'Partial migration, where only part of a population migrates, is widespread in the animal kingdom. Despite this, we know very little about the causes and consequences of partial migration, at least partly due to the logistical difficulties in collecting robust data in many species. I propose a project that takes advantage of an established and highly productive study system to answer fundamental questions about the evolution of partial migration in animals using an innovative combination of methods. Firstly, I will ask what drives some individuals to migrate and some to remain resident? Here I will empirically test predictions from a conceptual model that I recently developed which proposes that individual differences in predation risk and/or growth can explain patterns of partial migration. Specifically, I will investigate the role of an individual's position on a behavioural syndrome (i.e. personality) upon migratory behaviour, and predict that fish with bold personalities (that have high individual predation vulnerability) will be more likely to migrate than fish with shy personalities. I will also test the idea that individual differences in feeding niche (trophic polymorphism) influence an individual's migratory behaviour using stable isotope and geometric techniques. Secondly, I will investigate the population genetic consequences of partial migration, and assess its potential as a diversifying force in this system. The project will use a variety of cutting edge behavioural, ecological and molecular techniques to address these fundamental questions, using my established model system, the roach Rutilus rutilus. This novel project will provide a unique opportunity to answer questions on the evolution of partial migration, and indeed migration itself.'

Introduzione (Teaser)

Researchers have advanced our understanding of partial migration in a common fish species.

Descrizione progetto (Article)

During winter, roach fish (Rutilus rutilus) migrate from lakes to streams, but some members of the population remain behind. This phenomenon, which occurs widely in the animal kingdom, is called partial migration.

As part of the EU-funded 'Partial migration: Individual causes and population genetic consequences' (STAY OR GO) project, researchers studied the causes and effects of partial migration in roach.

They found migratory strategies to be highly consistent: some individuals tended to migrate every year, while others (termed residents) rarely migrated. The destinations and timing of migrations were also consistent.

Researchers investigated whether fish migrate to avoid predators in winter when food is low. They indeed found that residents had a significantly higher probability of being predated upon by cormorants, but that migrants sacrificed food for safety in streams.

They also determined that fish with bold personalities are more likely to migrate than shy fish, and that migratory fish have a different feeding niche to residents. In addition, fish from lakes offering the possibility to migrate (via connected streams) are on average more fusiform in body shape than fish from isolated lakes.

STAY OR GO findings have significantly advanced our understanding of the important ecological process known as partial migration. Further work will focus on whether migrants and residents breed with one another.