[1] Univ Stellenbosch, Dept Bot & Zool, ZA-7602 Stellenbosch, South Africa
[2] Towson Univ, Dept Biol, Towson, MD 21252 USA
[3] Int Inst Appl Syst Anal, Dynam Syst Program, Laxenburg, Austria
[4] Univ Maryland, Ctr Environm Sci, Chesapeake Biol Lab, Solomons, MD 20688 USA
[5] Univ Florida, Dept Bot & Zool, Gainesville, FL 32611 USA
[6] Alfred Wegener Inst, Wattenmeerstn, D-25992 List Auf Sylt, Germany