Supplementary material
Calculation of resistance cost values
Given the paucity of empirical movement or dispersal data available for Australian amphibian
species, we used literature and expert opinion to parameterise resistance surfaces. Literature
sources relating to the movement ecology or habitat preferences of the focal species within the
MDB were included in the resistance model, in addition to global amphibian studies involving
resistance values. These sources were used to rate individual landscape units on a consistent
rating scale by their movement difficulty relative to hypothetically optimal movement terrain.
Ratings were based on an integration of the species’ ability or willingness to cross a unit,
physiological costs incurred during crossing, and any risks of mortality associated with a unit
(Zeller et al. 2012). An exponential ratings scale was used with each rating step indicating a
relative increase of two times the resistance to movement of the previous step. This resulted in
a possible range of values between 1 (optimal movement terrain) and 128 (severe restriction to
movement or barrier). The maximum value of 128 was selected to provide a range of possible
resistances consistent with the magnitude of previous studies (e.g. Compton et al. 2007;
Greenwald et al. 2009; Lenhardt et al. 2013), and to provide a more conservative estimate of
movement potential than would be generated using the very large resistance values (e.g.
10,000) used in some studies to completely exclude the possibility of movement (e.g. Decout et
al. 2012).
Literature ratings were combined by assigning sources high weightings for quantitative
resistance values, or low ratings for qualitative movement or habitat descriptions (Table 1, 2).
Studies pertaining to closely related species believed to display similar movement behaviour
and habitat requirements (Limnodynastes tasmaniensis and Crinia signifera) were also included
in the model, but assigned lower weightings (Wassens 2010).
To increase the local relevance of parameter values and ensure that the resulting model
reflected the full range of landscape heterogeneity present across the MDB, six researchers with
a combined 130 years of research or field experience with the focal species and study area were
also invited to complete an expert opinion survey. Experts were presented with an identical list
of landscape units, and asked to assess each unit’s resistance to movement as well as their
certainty in this value. Certainty data were combined with weighted species-specific years of
experience (weighting of 1 for 0 to 10 years’ experience, 2 for 10 to 20 years, 3 for 20+ years) to
provide an overall confidence weighting for each survey unit. Weighted literature and expert
ratings were then combined by trimming extreme values (Compton et al. 2007; Zeller et al.
2012) before taking a weighted mean of the remaining values, resulting in conservative
resistance cost values which incorporated literature- and expert-specific uncertainty (Table 3).
1
Table 1. Values used to weight literature resistance to movement ratings. Weightings depended
on how taxonomically related the focal species of a study was to L. fletcheri or C. parinsignifera
(i.e. species, genus, order, or class level), the geographic location of the study area (i.e. MDB,
Australia, or global) and the type of study (with highest weightings being assigned to studies
with published resistance to movement values).
Studies on
Studies on
Studies on
Studies on
Studies on
Studies on
focal species focal species same genus same genus Anura order Amphibia class
MDB study
area
Australian
study area
MDB study
area
3.00
3.00
2.00
1.00
0.50
0.25
3.00
2.00
1.00
0.50
0.25
0
2.00
1.00
0.50
0.25
0
0
Quantitative habitat
studies
1.00
0.50
0.25
0
0
0
Qualitative habitat
descriptions
0.50
0.25
0
0
0
0
Least-cost or circuit
theory resistance values
Quantitative
movement or
connectivity studies
Qualitative movement
or connectivity
descriptions
Australian Global study
study area
area
Global study
area
2
Table 2. Literature used to develop resistance to movement ratings for C. parinsignifera and L.
fletcheri.
Literature
Focal species
Hazell et al. (2004) C. parinsignifera
Study species relevance
Study area Study type
C. parinsignifera (species)
MDB
C. parinsignifera (species)
MDB
C. parinsignifera (species)
MDB
C. parinsignifera (species)
MDB
C. parinsignifera
C. parinsignifera (species)
MDB
Hazell et al. (2001) C. parinsignifera
C. parinsignifera (species)
Australia
Lauck (2005)
C. parinsignifera
C. signifera (genus)
Australia
Mac Nally (1985)
C. parinsignifera
C. parinsignifera (species)
Australia
Wassens (2010)
C. parinsignifera
C. parinsignifera (species)
MDB
Anstis (2013)
C. parinsignifera
C. parinsignifera (species)
Australia
Cogger (2014)
C. parinsignifera
C. parinsignifera (species)
Australia
C. signifera (genus)
MDB
C. signifera (genus)
Australia
C. parinsignifera
C. signifera (genus)
Australia
Smith et al. (2007) C. parinsignifera
C. signifera (genus)
Australia
Ocock et al. (2014) L. fletcheri
L. fletcheri (species)
MDB
L. fletcheri (species)
MDB
L. fletcheri (species)
MDB
Healey et al.
C. parinsignifera
(1997)
Jansen and Healey
C. parinsignifera
(2003)
Mac Nally et al.
C. parinsignifera
(2009)
Ocock (2013)
Smallbone et al.
C. parinsignifera
(2011)
Canessa and Parris
C. parinsignifera
(2013)
Parris (2006)
Healey et al.
L. fletcheri
(1997)
Jansen and Healey
L. fletcheri
(2003)
Ocock (2013)
L. fletcheri
L. fletcheri (species)
MDB
Amey and Grigg
(1995)
L. fletcheri
L. fletcheri (species)
Australia
Wassens (2010)
L. fletcheri
L. fletcheri (species)
MDB
Anstis (2013)
L. fletcheri
L. fletcheri (species)
Australia
Cogger (2014)
L. fletcheri
L. fletcheri (species)
Australia
L. tasmaniensis (genus)
MDB
L. fletcheri
L. tasmaniensis (genus)
MDB
L. fletcheri
L. tasmaniensis (genus)
MDB
L. fletcheri
L. tasmaniensis (genus)
Australia
Smith et al. (2007) L. fletcheri
L. tasmaniensis (genus)
Australia
Anura (order)
Global
Anura (order)
Global
Amphibia (class)
Global
Amphibia (class)
Global
Hazell et al. (2004) L. fletcheri
Mac Nally et al.
(2009)
Smallbone et al.
(2011)
Parris (2006)
Decout et al.
(2012)
Lenhardt et al.
(2013)
Compton et al.
(2007)
Greenwald et al.
(2009)
L. fletcheri &
C. parinsignifera
L. fletcheri &
C. parinsignifera
L. fletcheri &
C. parinsignifera
L. fletcheri &
C. parinsignifera
Quantitative habitat
study
Quantitative habitat
study
Quantitative habitat
study
Quantitative habitat
study
Quantitative habitat
study
Quantitative habitat
study
Quantitative movement
or connectivity study
Quantitative habitat
study
Qualitative habitat
description
Qualitative habitat
description
Qualitative habitat
description
Quantitative habitat
study
Quantitative habitat
study
Quantitative habitat
study
Quantitative habitat
study
Quantitative movement
or connectivity study
Quantitative habitat
study
Quantitative habitat
study
Quantitative habitat
study
Quantitative habitat
study
Qualitative habitat
description
Qualitative habitat
description
Qualitative habitat
description
Quantitative habitat
study
Quantitative habitat
study
Quantitative habitat
study
Quantitative habitat
study
Quantitative habitat
study
Least-cost or circuit
theory resistance values
Least-cost or circuit
theory resistance values
Least-cost or circuit
theory resistance values
Least-cost or circuit
theory resistance values
Weight
1.000
1.000
1.000
1.000
1.000
0.500
0.500
0.500
0.500
0.250
0.250
0.250
0.125
0.125
0.125
3.000
1.000
1.000
1.000
0.500
0.500
0.250
0.250
0.250
0.250
0.250
0.125
0.125
0.500
0.500
0.250
0.250
3
Table 3. Landscape units and resistance cost values used to develop resistance surfaces. Low
resistance values indicate optimal movement terrain, while high values indicate increasing
resistance to movement.
L.
fletcheri
1.0
C.
parinsignifera
1.0
1.0
1.0
7.2
8.9
1.0
1.0
6.0
10.3
5.3
3.9
1.6
3.8
42.2
53.3
9.0
5.8
2.0
2.2
9.2
5.8
4.9
2.9
3.5
2.8
2.3
1.5
6.8
5.6
4.6
2.6
4.8
5.1
7.8
5.8
4.9
7.7
Built Up Area†
39.0
36.9
Extraction Sites*, Mine Area†
Sealed Minor Road†
Secondary Road†
11.0
11.9
13.9
16.7
7.4
11.8
Principal Road†
28.8
28.2
Dual Carriageway†
72.1
91.6
Railway†
21.2
33.3
Landscape unit
Matching features and data source
Recently inundated terrain
MDB-FIM2 inundation extent
Inland Waterbodies*,
Water Points – Pool, Waterhole, Well & Spring,
Lakes – Wetland, Claypan, Waterhole & Shallows†
Small or shallow natural
waterbodies or wetlands
Large or deep natural
waterbodies
Small or shallow
watercourses
Large or deep watercourses
Water storage
infrastructure
Water supply
infrastructure
Saline waters
Arid or semi-arid
hummock grassland
Arid or semi-arid
tussock grassland
Arid or semi-arid
shrubland
Arid or semi-arid woodland
Temperate woodland
Temperate forests
Cleared or bare land
Dryland crops
Irrigated crops
Dryland grazing
Irrigated grazing
Urban or industrial
infrastructure
Mining or waste
Sealed minor roads
Secondary roads
Principal roads or
highways
Freeway or dual
carriageway
Railway lines
Lakes – Lake†
Watercourse Areas – Minor,
Watercourse Lines – Minor†
Watercourse Areas – Major,
Watercourse Lines – Major†
Lakes - Town Rural Storage, Flood Irrigation
Farming, Ash Dam & Earth Tank†,
Large Dams - Town Rural Storage‡
Canal Line, Canal Area†
Salt Lakes*, Lakes – Salt & Salt Disposal Basin†
Hummock Grasses – Sparse & Open*
Tussock Grasses – Scattered, Sparse & Open,
Grassland – Scattered, Sparse & Open,
Alpine Grasses – Open, Sedges – Open,
Forbs – Sparse & Open*
Shrubs – Scattered, Sparse & Open,
Chenopod Shrubs – Scattered, Sparse & Open*
Trees – Scattered, Sparse & Open (arid/semi-arid)*
Trees – Scattered, Sparse & Open (temperate)*
Trees – Closed*
Cleared Line, Lakes – Reclaimed Scalded Claypan,
Old Dry Lake & Under Cultivation†
Rainfed Cropping, Rainfed Sugar*
Irrigated Cropping, Irrigated Sugar*
Rainfed Pasture*
Irrigated Pasture*
* Dynamic Land Cover Dataset (GA 2011), † GEODATA TOPO 250K (GA 2006), ‡ MDB Waterbodies Project (GA 2010)
4
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