Anthropogenic landscape change promotes asymmetric dispersal and limits regional patch occupancy in a spatially structured bird population

Pavlacky, David C., Possingham, Hugh P., Lowe, Andrew J., Prentis, Peter J., Green, David J. and Goldizen, Anne W. (2012) Anthropogenic landscape change promotes asymmetric dispersal and limits regional patch occupancy in a spatially structured bird population. Journal of Animal Ecology, 80 5: 940-952.


Author Pavlacky, David C.
Possingham, Hugh P.
Lowe, Andrew J.
Prentis, Peter J.
Green, David J.
Goldizen, Anne W.
Title Anthropogenic landscape change promotes asymmetric dispersal and limits regional patch occupancy in a spatially structured bird population
Journal name Journal of Animal Ecology   Check publisher's open access policy
ISSN 0021-8790
1365-2656
Publication date 2012-09
Sub-type Article (original research)
DOI 10.1111/j.1365-2656.2012.01975.x
Volume 80
Issue 5
Start page 940
End page 952
Total pages 13
Place of publication Oxford, United Kingdom
Publisher Wiley-Blackwell Publishing
Collection year 2013
Language eng
Formatted abstract 1. Local extinctions in habitat patches and asymmetric dispersal between patches are key processes structuring animal populations in heterogeneous environments. Effective landscape conservation requires an understanding of how habitat loss and fragmentation influence demographic processes within populations and movement between populations.

2. We used patch occupancy surveys and molecular data for a rainforest bird, the logrunner (Orthonyx temminckii), to determine (i) the effects of landscape change and patch structure on local extinction; (ii) the asymmetry of emigration and immigration rates; (iii) the relative influence of local and between-population landscapes on asymmetric emigration and immigration; and (iv) the relative contributions of habitat loss and habitat fragmentation to asymmetric emigration and immigration.

3. Whether or not a patch was occupied by logrunners was primarily determined by the isolation of that patch. After controlling for patch isolation, patch occupancy declined in landscapes experiencing high levels of rainforest loss over the last 100 years. Habitat loss and fragmentation over the last century was more important than the current pattern of patch isolation alone, which suggested that immigration from neighbouring patches was unable to prevent local extinction in highly modified landscapes.

4. We discovered that dispersal between logrunner populations is highly asymmetric. Emigration rates were 39% lower when local landscapes were fragmented, but emigration was not limited by the structure of the between-population landscapes. In contrast, immigration was 37% greater when local landscapes were fragmented and was lower when the between-population landscapes were fragmented. Rainforest fragmentation influenced asymmetric dispersal to a greater extent than did rainforest loss, and a 60% reduction in mean patch area was capable of switching a population from being a net exporter to a net importer of dispersing logrunners.

5. The synergistic effects of landscape change on species occurrence and asymmetric dispersal have important implications for conservation. Conservation measures that maintain large patch sizes in the landscape may promote asymmetric dispersal from intact to fragmented landscapes and allow rainforest bird populations to persist in fragmented and degraded landscapes. These sink populations could form the kernel of source populations given sufficient habitat restoration. However, the success of this rescue effect will depend on the quality of the between-population landscapes.
Keyword Asymmetric gene flow
Asymmetric migration
Bird conservation
Coalescent theory
Detection probability
Dispersal asymmetry
Landscape ecology
Landscape genetics
Microsatellite DNA
Subtropical rainforest
Open Access Mandate Compliance Yes - Open Access (Publisher DOI)
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2013 Collection
School of Biological Sciences Publications
 
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Created: Wed, 31 Oct 2012, 14:00:34 EST by Gail Walter on behalf of School of Biological Sciences