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, andany 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 (Limnodynastestasmaniensisand Criniasignifera) 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 identicallist 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)beforetaking a weighted mean of the remaining values, resulting in conservative resistance cost values which incorporated literature- and expert-specific uncertainty (Table 3).

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 focal species
MDB study area / Studies on focal species
Australian study area / Studies on same genus
MDB study area / Studies on same genus
Australian study area / Studies on Anura order
Global study area / Studies on Amphibia class
Global study area
Least-cost or circuit theory resistance values / 3.00 / 3.00 / 2.00 / 1.00 / 0.50 / 0.25
Quantitative movement or connectivity studies / 3.00 / 2.00 / 1.00 / 0.50 / 0.25 / 0
Qualitative movement or connectivity descriptions / 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
Literature / Focal species / Study species relevance / Study area / Study type / Weight
Hazell et al. (2004) / C. parinsignifera / C. parinsignifera (species) / MDB / Quantitative habitat study / 1.000
Healey et al. (1997) / C. parinsignifera / C. parinsignifera (species) / MDB / Quantitative habitat study / 1.000
Jansen and Healey (2003) / C. parinsignifera / C. parinsignifera (species) / MDB / Quantitative habitat study / 1.000
Mac Nally et al. (2009) / C. parinsignifera / C. parinsignifera (species) / MDB / Quantitative habitat study / 1.000
Ocock (2013) / C. parinsignifera / C. parinsignifera (species) / MDB / Quantitative habitat study / 1.000
Hazell et al. (2001) / C. parinsignifera / C. parinsignifera (species) / Australia / Quantitative habitat study / 0.500
Lauck (2005) / C. parinsignifera / C. signifera(genus) / Australia / Quantitative movement or connectivity study / 0.500
Mac Nally (1985) / C. parinsignifera / C. parinsignifera (species) / Australia / Quantitative habitat study / 0.500
Wassens (2010) / C. parinsignifera / C. parinsignifera (species) / MDB / Qualitative habitat description / 0.500
Anstis (2013) / C. parinsignifera / C. parinsignifera (species) / Australia / Qualitative habitat description / 0.250
Cogger (2014) / C. parinsignifera / C. parinsignifera (species) / Australia / Qualitative habitat description / 0.250
Smallbone et al. (2011) / C. parinsignifera / C. signifera(genus) / MDB / Quantitative habitat study / 0.250
Canessa and Parris (2013) / C. parinsignifera / C. signifera(genus) / Australia / Quantitative habitat study / 0.125
Parris (2006) / C. parinsignifera / C. signifera(genus) / Australia / Quantitative habitat study / 0.125
Smith et al. (2007) / C. parinsignifera / C. signifera(genus) / Australia / Quantitative habitat study / 0.125
Ocock et al. (2014) / L. fletcheri / L. fletcheri(species) / MDB / Quantitative movement or connectivity study / 3.000
Healey et al. (1997) / L. fletcheri / L. fletcheri(species) / MDB / Quantitative habitat study / 1.000
Jansen and Healey (2003) / L. fletcheri / L. fletcheri(species) / MDB / Quantitative habitat study / 1.000
Ocock (2013) / L. fletcheri / L. fletcheri(species) / MDB / Quantitative habitat study / 1.000
Amey and Grigg (1995) / L. fletcheri / L. fletcheri(species) / Australia / Quantitative habitat study / 0.500
Wassens (2010) / L. fletcheri / L. fletcheri(species) / MDB / Qualitative habitat description / 0.500
Anstis (2013) / L. fletcheri / L. fletcheri(species) / Australia / Qualitative habitat description / 0.250
Cogger (2014) / L. fletcheri / L. fletcheri(species) / Australia / Qualitative habitat description / 0.250
Hazell et al. (2004) / L. fletcheri / L. tasmaniensis(genus) / MDB / Quantitative habitat study / 0.250
Mac Nally et al. (2009) / L. fletcheri / L. tasmaniensis(genus) / MDB / Quantitative habitat study / 0.250
Smallbone et al. (2011) / L. fletcheri / L. tasmaniensis(genus) / MDB / Quantitative habitat study / 0.250
Parris (2006) / L. fletcheri / L. tasmaniensis(genus) / Australia / Quantitative habitat study / 0.125
Smith et al. (2007) / L. fletcheri / L. tasmaniensis(genus) / Australia / Quantitative habitat study / 0.125
Decout et al. (2012) / L. fletcheri
C. parinsignifera / Anura(order) / Global / Least-cost or circuit theory resistance values / 0.500
Lenhardt et al. (2013) / L. fletcheri
C. parinsignifera / Anura(order) / Global / Least-cost or circuit theory resistance values / 0.500
Compton et al. (2007) / L. fletcheri
C. parinsignifera / Amphibia(class) / Global / Least-cost or circuit theory resistance values / 0.250
Greenwald et al. (2009) / L. fletcheri
C. parinsignifera / Amphibia(class) / Global / Least-cost or circuit theory resistance values / 0.250

Table 2.Literature used to developresistance to movement ratings for C. parinsignifera and L.fletcheri.

Table 3.Landscape units and resistance cost values used to develop resistance surfaces. Low resistance values indicate optimal movement terrain, while high values indicate increasingresistance to movement.

Landscape unit

/

Matching features and data source

/

L.

fletcheri

/

C. parinsignifera

Recently inundated terrain / MDB-FIM2 inundation extent / 1.0 / 1.0
Small or shallow natural waterbodies or wetlands / Inland Waterbodies*,
Water Points – Pool, Waterhole, Well & Spring,
Lakes – Wetland, Claypan, Waterhole Shallows† / 1.0 / 1.0
Large or deep natural waterbodies / Lakes – Lake† / 7.2 / 8.9
Small or shallow watercourses / Watercourse Areas – Minor,
Watercourse Lines – Minor† / 1.0 / 1.0
Large or deep watercourses / Watercourse Areas – Major,
Watercourse Lines – Major† / 6.0 / 10.3
Water storage infrastructure / Lakes - Town Rural Storage, Flood Irrigation Farming, Ash Dam & Earth Tank†,
Large Dams - Town Rural Storage‡ / 5.3 / 3.9
Water supply infrastructure / Canal Line, Canal Area† / 1.6 / 3.8
Saline waters / Salt Lakes*, Lakes – Salt & Salt Disposal Basin† / 42.2 / 53.3
Arid or semi-arid
hummock grassland / Hummock Grasses – Sparse & Open* / 9.0 / 5.8
Arid or semi-arid
tussock grassland / Tussock Grasses – Scattered, Sparse & Open,
Grassland – Scattered, Sparse & Open,
Alpine Grasses – Open, Sedges – Open,
Forbs – Sparse & Open* / 2.0 / 2.2
Arid or semi-arid shrubland / Shrubs – Scattered, Sparse & Open,
Chenopod Shrubs – Scattered, Sparse & Open* / 9.2 / 5.8
Arid or semi-arid woodland / Trees – Scattered, Sparse & Open (arid/semi-arid)* / 4.9 / 2.8
Temperate woodland / Trees – Scattered, Sparse & Open (temperate)* / 2.9 / 2.3
Temperate forests / Trees – Closed* / 3.5 / 1.5
Cleared or bare land / Cleared Line, Lakes – Reclaimed Scalded Claypan, Old Dry Lake & Under Cultivation† / 6.8 / 5.6
Dryland crops / Rainfed Cropping, Rainfed Sugar* / 4.6 / 7.8
Irrigated crops / Irrigated Cropping, Irrigated Sugar* / 2.6 / 5.8
Dryland grazing / Rainfed Pasture* / 4.8 / 4.9
Irrigated grazing / Irrigated Pasture* / 5.1 / 7.7
Urban or industrial infrastructure / Built Up Area† / 39.0 / 36.9
Mining or waste / Extraction Sites*, Mine Area† / 11.0 / 16.7
Sealed minor roads / Sealed Minor Road† / 11.9 / 7.4
Secondary roads / Secondary Road† / 13.9 / 11.8
Principal roads or highways / Principal Road† / 28.8 / 28.2
Freeway or dual carriageway / Dual Carriageway† / 72.1 / 91.6
Railway lines / Railway† / 21.2 / 33.3
* Dynamic Land Cover Dataset (GA 2011), † GEODATA TOPO 250K (GA 2006), ‡ MDB Waterbodies Project (GA 2010)

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