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Explaining leptokurtic movement distributions: intrapopulation variation in boldness and exploration.
D F Fraser1, J F Gilliam, M J Daley
1Department of Biology, Siena College, Loudonville, New York 12211, USA. fraser@siena.edu
The American Naturalist
|August 19, 2008
Summary
Persistent leptokurtosis in animal movement suggests population heterogeneity. Bold Trinidad killifish (Rivulus hartii) exhibited greater movement, linking behavior to dispersal and fitness in hazardous habitats.
Area of Science:
- Ecology
- Animal Behavior
- Evolutionary Biology
Background:
- Leptokurtic movement distributions, where most individuals move short distances and a few move long distances, are common in mobile animals.
- Persistent leptokurtosis suggests population heterogeneity, as it's predicted to be transient in homogeneous populations.
Purpose of the Study:
- To investigate the heterogeneity generating persistent leptokurtosis in animal movement.
- To determine if individual behavioral traits, beyond size and sex, influence dispersal.
- To examine the relationship between individual growth, movement, and habitat hazardousness.
Main Methods:
- Field-release studies of Trinidad killifish (Rivulus hartii).
- Tank tests to assess individual boldness.
- Mark-recapture study over 19 months.
- Analysis of movement distances in relation to boldness, size, sex, and growth in predator-threatened versus predator-absent zones.
Main Results:
- Individual boldness in tank tests predicted movement distance in field releases, independent of size and sex.
- In a predator-threatened, fragmented river zone, individual growth correlated positively with movement.
- This growth-movement correlation was absent in a predator-absent, unfragmented zone.
Conclusions:
- A behavioral trait (boldness) contributes to dispersal in Rivulus hartii.
- Dispersal in hazardous habitats can elevate the fitness of 'dispersers' above 'stayers'.
- This finding supports models of the evolution of dispersal in challenging environments.
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