The effects of habitat fragmentation due to forestry plantation establishment on the demography and genetic variation of a marsupial carnivore, Antechinus agilis

Banks, S. C., Finlayson, G. R., Lawson, S. J., Lindenmayer, D. B., Paetkau, D., Ward, S. J. and Taylor, A. C. (2005) The effects of habitat fragmentation due to forestry plantation establishment on the demography and genetic variation of a marsupial carnivore, Antechinus agilis. Biological Conservation, 122 4: 581-597. doi:10.1016/j.biocon.2004.09.013


Author Banks, S. C.
Finlayson, G. R.
Lawson, S. J.
Lindenmayer, D. B.
Paetkau, D.
Ward, S. J.
Taylor, A. C.
Title The effects of habitat fragmentation due to forestry plantation establishment on the demography and genetic variation of a marsupial carnivore, Antechinus agilis
Journal name Biological Conservation   Check publisher's open access policy
ISSN 0006-3207
Publication date 2005-04-01
Sub-type Article (original research)
DOI 10.1016/j.biocon.2004.09.013
Volume 122
Issue 4
Start page 581
End page 597
Total pages 17
Place of publication Essex, England
Publisher Elsevier
Collection year 2005
Language eng
Subject C1
270203 Population and Ecological Genetics
780105 Biological sciences
0599 Other Environmental Sciences
0699 Other Biological Sciences
Abstract We conducted a demographic and genetic study to investigate the effects of fragmentation due to the establishment of an exotic softwood plantation on populations of a small marsupial carnivore, the agile antechinus (Antechinus agilis), and the factors influencing the persistence of those populations in the fragmented habitat. The first aspect of the study was a descriptive analysis of patch occupancy and population size, in which we found a patch occupancy rate of 70% among 23 sites in the fragmented habitat compared to 100% among 48 sites with the same habitat characteristics in unfragmented habitat. Mark-recapture analyses yielded most-likely population size estimates of between 3 and 85 among the 16 occupied patches in the fragmented habitat. Hierarchical partitioning and model selection were used to identify geographic and habitat-related characteristics that influence patch occupancy and population size. Patch occupancy was primarily influenced by geographic isolation and habitat quality (vegetation basal area). The variance in population size among occupied sites was influenced primarily by forest type (dominant Eucalyptus species) and, to a lesser extent, by patch area and topographic context (gully sites had larger populations). A comparison of the sex ratios between the samples from the two habitat contexts revealed a significant deficiency of males in the fragmented habitat. We hypothesise that this is due to male-biased dispersal in an environment with increased dispersal-associated mortality. The population size and sex ratio data were incorporated into a simulation study to estimate the proportion of genetic diversity that would have been lost over the known timescale since fragmentation if the patch populations had been totally isolated. The observed difference in genetic diversity (gene diversity and allelic richness at microsatellite and mitochondrial markers) between 16 fragmented and 12 unfragmented sites was extremely low and inconsistent with the isolation of the patch populations. Our results show that although the remnant habitat patches comprise approximately 2% of the study area, they can support non-isolated populations. However, the distribution of agile antechinus populations in the fragmented system is dependent on habitat quality and patch connectivity. (C) 2004 Elsevier Ltd. All rights reserved.
Keyword Biodiversity Conservation
Ecology
Environmental Sciences
Habitat Fragmentation
Genetic Variation
Antechinus
Softwood Plantation
Patch Occupancy
Abundance
South-eastern Australia
Small Mammals
Eucalypt Forests
Large-scale
Populations
Stuartii
Dasyuridae
Landscape
Conservation
Dispersal
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collections: 2006 Higher Education Research Data Collection
School of Biological Sciences Publications
 
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Created: Wed, 15 Aug 2007, 15:21:46 EST