The eleventh installment of the 2009 Science Seminar Series presented by Doctor Melanie Lancaster. The presentation is entitled "Pines and paddocks: socioecology and population genetics of marsupials in fragmented systems?"

1. The Environment Institute
Where ideas grow
Dr Melanie Lancaster
Pines and paddocks: Socioecology and population
genetics of marsupials in fragmented systems

2. Pines and paddocks: Socio-ecology and
population genetics of marsupials
in fragmented south-eastern Australia
Melanie Lancaster
Earth and Environmental Sciences
The University of Adelaide
Steven J.B. Cooper, Susan Carthew, Andrea C. Taylor

3. Molecular Ecology
INDIVIDUAL POPULATION SPECIES
Use of genetic tools to answer ecologically important
questions
Identification of individuals to a source population
Population processes: migration, dispersal (ie. juvenile, sex-biased), GENE
FLOW
Social structure: Mating systems, site fidelity, mate fidelity
Predict species responses to environmental changes, human impacts, etc.

4. Background (mine)
PhD research
• Small population of fur seals on Macquarie Island
• Suspected interbreeding among three species
– Different recolonisation histories
• Tissue samples collected from entire pup cohorts between
1992 and 2003
• Extensive observational data – territory locations,
pupping sites
• Species composition of the population
• Hybrids?
• Costs of hybridisation?

5. PhD research – species identification
Genetic screening of individuals =>
70 identification to a source species or
hybrid class
60
50
% PUPS
40
30
20
10
0
1992 1994 1996 1998 2000 2002
YEAR
Lancaster et al. (2006)
Molecular Ecology

6. PhD research – mating systems
Genetic analysis of paternity =>
identify fitness cost to
hybridisation
Lancaster et al. (2007)
Molecular Ecology

7. Molecular Ecology
INDIVIDUAL POPULATION SPECIES
Use of genetic tools to answer ecologically important
questions
Identification of individuals to a source population
Population processes: migration, dispersal (ie. juvenile, sex-biased), GENE FLOW
Social structure: Mating systems, site fidelity, mate fidelity
Predict species responses to environmental changes, human
impacts, etc.

8. Forest Fragmentation
• Deforestation as old as the human
occupation of the earth (Williams 2003)
• Process has affected more of the earth’s
surface
Laurance and Beirregaard 1997:
• Preserve what we have
• Plan the future landscape
• Manage what is left
Species ecology
Multi-species approaches

9. Fragmentation in Australia
Source: http://adl.brs.gov.au/anrdl/metadata/overviews/alccdr9ab__004/alccdr9ab__00411a10b.pdf

10. SA - the Lower South-East
Pre-European Settlement
• Flora diverse
• E. baxteri and E. viminalis forests
and woodlands dominated
Post-Settlement
• Large areas cleared after WWII for softwood
and agricultural land
• 13 % native vegetation remains
• Vegetation community composition changed
• Remaining veg adapted to poor soils and
poor drainage, incomplete representation
• Remnants surrounded by cropland, pastures,
pines
• Habitats that once supported native fauna
may no longer be present

11. Study site
The “Greater Green Triangle” region…when green is bad
• Largest wood fibre producing region in Australia
• Dry, sclerophyll forests isolated by pine stands of various ages

12. Mammal species
Arboreal and terrestrial
Sugar gliders, yellow-bellied gliders, Common brushtail and
ringtail possums, microbats
Native rats, mice, southern brown bandicoot, yellow-footed
Antechinus, wallabies (swamp, red-necked), kangaroos,
wombats, echidnas

13. Consequences of fragmentation
Populations may become isolated if:
• Distances between fragments too great to traverse
• Surrounding habitat too difficult to move through, acts as a barrier to
dispersal
Individuals within populations do not move out of patch
• Populations become isolated over time and genetically differentiated
from each other
• Within patches, results in increased relatedness, inbreeding, loss of
genetic diversity Dispersal = ?gene flow
No dispersal = NO gene flow
To assess the impacts of forest fragmentation on
population processes in key marsupial species

14. ARC Linkage
Conservation genetics and socio-ecology of marsupials
in fragmented populations of south-eastern South
Australia: towards a regional biodiversity
management plan
A/Prof Sue Carthew, Dr Steve Cooper, Dr Andrea Taylor
PARTNERS:
To assess the impacts of forest fragmentation on
population processes in key marsupial species

15. Fragmentation case studies
Factors affecting population connectivity in fragmented
landscapes:
• Age of regrowth forest
• Surrounding matrix
• Habitat shape, edge effects
• Lemurs, bird spp., gorillas, pademelons, bats, reptiles, frogs
Sugar gliders (Mansoureh Malekien)
• Restricted gene flow among some patches
• Effects greater in small patches isolated by pine
• Evidence for inbreeding in one patch from parentage analysis
Yellow-footed antechinus (Amanda McLean)
• Some evidence of differentiation between populations
• Higher relatedness among females within patches than in continuous
forest

16. Common ringtail possum
• Nocturnal arboreal marsupial
• Broad distribution, abundant in a variety of forest habitats
• Generalist herbivore – leaves, flowers, seeds of eucalypt spp., acacia
spp.
• Can build dreys
• Survives in degraded habitats, found in fragmented landscapes

17. Study site
10 23
11
21
18 30
10 35
23
20 47
7
23
15
78
43 74

18. Data collection
Site selection based on:
• patch size
• distance to neighbouring patch (0.5-
>10 km)
• 3 sites within continuous forest
(distances between sites comparable)
• 251 possums patches within pine
• 189 possums patches within agriculture
• 48 from 3 continuous forest sites
• Genotyped at 15 microsatellites
• Analysed for genetic diversity and genetic differentiation

19. 1. Genetic Diversity
Have possums in patches retained
genetic diversity?
• HH and L sig. Lower allelic
richness and heterozygosity
• Larger patches levels
comparable to continuous
forest
• Trend towards lower H and
AR in ag patches
YES for some, NO for others,
not related to patch size
alone

20. 2. Population structure
Do possums move through the pine?
• Five distinct clusters identified from 8 populations
sampled 
• No sub-structure within continuous forest 
• HH and L genetically isolated 
• P a subset of continuous forest 
• SG, W and HS virtually same cluster membership 
Yes, but pine hinders dispersal and gene flow
Less dispersal into small, isolated patches

21. 2. Population structure
Do possums move through paddocks
and roadside vegetation?
8 distinct genetic clusters
identified
Significant pop structure
and isolation
Limited evidence of gene
flow/dispersal

22. Pop Differentiation
HH HS L P REN SG W WD
HH
HS 0.05
L 0.19 0.12
P 0.11 0.03 0.17
REN 0.10 0.03 0.13 0.00
SG 0.08 0.03 0.12 0.03 0.04
W 0.06 0.04 0.14 0.05 0.07 0.04
WD 0.09 0.02 0.13 0.02 0.02 0.03 0.05
BG G HC M PS RR SQ REN
BG
G 0.08
HC 0.08 0.07
Population pair-wise FST shows all M 0.06 0.04 0.08
pops except P and R as significantly PS 0.04 0.08 0.11 0.05
RR 0.08 0.11 0.09 0.08 0.09
different (most p < 0.0001) SQ 0.07 0.05 0.07 0.02 0.06 0.07
REN 0.03 0.04 0.06 0.03 0.04 0.05 0.03
Patches vs Continuous
R1 R2 R3 No sig difference between R1 and R2
R1 0.12 <0.0001 (2.5 km)
R2 0.007 <0.01 Sig. Differentiation of R3 from other
R3 0.038 0.033 patches (3 km)

23. Dispersal patterns
• Mammalian patterns of dispersal
– Sex-biased
– Males disperse as juveniles or young adults
– Females philopatric
• In fragmented landscapes these patterns may be
disrupted if movement is inhibited
• Use genetic relatedness to look at patterns

24. PINE PADDOCKS
P and SG not sig
Males Males
0.600 0.300
0.400 0.200
0.100
0.200 Mean
0.000
r
0.000 U
-0.100
-0.200 L
-0.200
-0.400 BG G HC M PS RR SQ
HH HS L P SG W WD
Females Females
0.800 0.300
0.600 0.200
0.400
0.100
r
0.200
0.000
0.000
-0.100
-0.200
-0.200
HH HS L P SG W WD
BG G HC Patch
M PS RR SQ
Patch
Continuous Forest All others sig. higher relatedness than
0.300
0.200
expected by chance
0.100 Mean
Both sexes show this trend
r
0.000
U
-0.100
L
-0.200
R1 M R2 M R3 M R1 F R2 F R3 F cf continuous forest neither females or
Patch males show this pattern

25. Summary
• Intervening matrices appear to hinder dispersal and gene flow of
possums
– Less problematic in larger patches than smaller ones
– Larger patches have comparable genetic diversity to continuous forest
– Smaller patches HH and L show signatures of genetic isolation through low
heterozygosity and lower allelic diversity.
• Findings of lower dispersal in both sexes in fragments important
implications for social structure and mating system
• Pastoral land has greater impact on ringtail possums
– Depend on several factors
• Patch size
• Age of pine
• Distance to neighbouring patch
• Time since isolation

26. Recommendations and What next?
– Modelling – which factors affect connectivity – position/distance/
size of patch but need to quantify
– Incorporate landscape features – roadside vegetation, plantations,
grazed remnant vegetation. Circuitscape (uses algorithms from
electronic circuit theory to predict patterns of dispersal)
– Incorporate more species
• Corridors to join patches on the periphery of landscapes
• Multiple potential sources of immigration important for genetic
diversity
• Continued conservation of large patches that can
support viable populations to maintain remaining communities

27. Acknowledgements
Field volunteers for valuable Australian Research Council Linkage
assistance with possuming Grants Scheme, with partners:
• Department for the Environment
and Heritage
Martin Pepper for providing
• Forestry SA
photographs • Hancock Victorian Plantations
• Nature Foundation of South
Kathy Saint for assistance Australia
with microsatellite development • South Australian Museum

28. The Environment Institute
Where ideas grow
Next Seminar: 27 November
Professor Kym Anderson
Regional implications of climate change for the Australian
wine industry