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The evolution of mammalian natal dispersal patterns

close up of a second social group in study colony

General patterns and discussed evolutionary forces

Natal dispersal (i.e. dispersal from the natal group or area prior to sexual maturity) is usually sex-biased with female-biased natal dispersal prevailing in the majority of bird species while male-biased natal dispersal prevails in mammals. The main discussed evolutionary forces shaping natal dispersal patterns include the avoidance of inbreeding, the avoidance of local mate competition, the avoidance of local resource competition and kin cooperation. Though, there is still much disagreement about the relative importance of these ultimate causes for sex-biased natal dispersal. Studying exceptions to general patterns of natal dispersal, e.g. female-biased natal dispersal in mammals, provides a valuable opportunity to test the validity and relative importance of proposed evolutionary pressures.

Aims and methods

This project aims to contribute to our understanding of natal dispersal pattern evolution by studying Proboscis bats (Rhynchonycteris naso) – a bat of a family (Emballonuridae) that is known for its diversity in natal dispersal patterns and social systems. We examine the earlier proposed exceptional all-offspring natal dispersal in R. naso as well as its social structure and mating system to evaluate proposed selective pressures in the evolution of natal dispersal patterns. To achieve this, we use an integrated approach of exhaustive long-term behavioural observations of individually banded R. naso and genetic paternity and kinship analysis.

Publications (selection)

Nagy M, Günther L, Knörnschild M, Mayer F. 2013 Female-biased dispersal in a bat with a female-defence mating strategy. Molecular ecology 22, 1733–1745. (doi:10.1111/mec.12202)

Günther L, Lopez MD, Knörnschild M, Reid K, Nagy M, Mayer F. 2016 From resource to female defence: the impact of roosting ecology on a bat’s mating strategy. Royal Society Open Science 3, 160503. (doi:10.1098/rsos.160503)

Günther L, Knörnschild M, Nagy M, Mayer F. 2017 The evolution of a rare mammalian trait – benefits and costs of male philopatry in proboscis bats. Scientific Reports 7, 15632. (doi:10.1038/s41598-017-15990-6)

  • bat colony under the extended roof of a station cabin at La Selva Biological Station
  • close up of a social bat group under the extended roof of a station cabin at La Selva Biological Station