The straight and narrow path: the evolution of straight-line dispersal at a cane toad invasion front

Gregory P. Brown, Benjamin L. Phillips, Richard Shine*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

78 Citations (Scopus)


At the edge of a biological invasion, evolutionary processes (spatial sorting, natural selection) often drive increases in dispersal. Although numerous traits influence an individual’s displacement (e.g. speed, stamina), one of the most important is path straightness. A straight (i.e. highly correlated) path strongly enhances overall dispersal rate relative to time and energetic cost. Thus, we predict that, if path straightness has a genetic basis, organisms in the invasion vanguard will exhibit straighter paths than those following behind. Our studies on invasive cane toads (Rhinella marina) in tropical Australia clearly support this prediction. Radio-tracking of field-collected toads at a single site showed that path straightness steadily decreased over the first 10 years post-invasion. Consistent with an evolved (genetic) basis to that behavioural shift, path straightness of toads reared under common garden conditions varied according to the location of their parents’ origin. Offspring produced by toads from the invasion vanguard followed straighter paths than did those produced by parents from long-established populations.At the individual level, offspring exhibited similar path straightness to their parents. The dramatic acceleration of the cane toad invasion through tropical Australia has been driven, in part, by the evolution of a behavioural tendency towards dispersing in a straight line.

Original languageEnglish
Article number20141385
Pages (from-to)1-7
Number of pages7
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1795
Publication statusPublished - 22 Nov 2014
Externally publishedYes


  • Bufo marinus
  • range expansion
  • spatial sorting
  • circular variance
  • fractal dimension
  • tortuosity
  • Spatial sorting
  • Circular variance
  • Fractal dimension
  • Tortuosity
  • Range expansion


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