Fig 1.
Diagrammatic summary of the variation in placement and size of biogeographic barriers previously illustrated or described in the Australian tropics.
Coloured blocks represent gaps or points of disjunction between species and populations, and typically extend from the coast towards the center of the continent. References for each putative barrier are provided in the table (see S1 Document for full references), with asterisks denoting where barriers are unnamed, or described but not explicitly illustrated. The underlying vegetation structure map is modified from the Joint Remote Sensing Project (persistent URL: http://auscover.org.au/purl/icesat-vegetation-structure) and is used under a CC BY 4.0 License.
Fig 2.
The Australian continent with shading indicating the frequency of monsoonal conditions (modified from [17]).
Black dashed line indicates typically recognised southern limit of the monsoon zone. White dashed lines mark the three largest putative biogeographic barriers used as the a priori seed for this study, and thought to divide the monsoon tropics into four main regions (The Pilbara, The Kimberley, The Top End, and Cape York Peninsula). The Arnhemland Plateau, Wet Tropics and Great Dividing Range are also indicated. The map outline was modified from Geoscience Australia (http://www.ga.gov.au/metadata-gateway/metadata/record/61754/) and is used under a CC BY 4.0 license.
Fig 3.
The thirteen shared disjunctions identified in this study.
Circled letters denote zones of common disjunction. Numbers indicate species recorded in each putative region of disjunction and associated flanking regions. White dotted lines indicate the divisions in flanking regions applied between the Carpentaria Basin and the Arnhem Land Plateau, and between the Carpentaria Basin and the Normanby Basin.
Fig 4.
Disjunct and range-end patterns for species in or adjacent to putative barriers, and how they were scored.
Shaded regions represent occurrence of one species.
Table 1.
Description and notes on the 13 putative barriers identified in this study, as illustrated in Fig 3.
Table 2.
Results of tests of the hypotheses (1) that putative barriers are impermeable (species occur more frequently in either flank and less frequently on both sides the barrier), and (2) that species’ ranges end at a barrier more frequently than expected by chance.
A plus sign (+) indicates a significantly higher frequency than expected, a minus sign (-) a significantly lower frequency than expected, and ‘ns’ indicates non-significance. As the second test was one-tailed, the only possible outcomes were ‘+’ or ‘ns’. Rows for the two barriers in the Australian Wet Tropics are shaded.