Seed dispersal by dung beetles in Ceratocaryum pulchrum (Restionaceae) : another example of faecal mimicry in plants

Abstract

Faecal mimicry by seeds is a recently discovered phenomenon in plants. Here we demonstrate that seeds of Ceratocaryum pulchrum (Restionaceae) are dispersed and buried by dung beetles, making it the second species, after its sister species C. argenteum, known to exhibit this mode of dispersal. Seeds of C. pulchrum are similar in size, shape and scent to those of C. argenteum and the dung of various mammalian herbivores. The distribution range of C. pulchrum entirely overlaps with that of C. argenteum, but they flower and release seeds six months apart. Several dung beetle species, including both of those associated with C. argenteum, were found to be attracted to C. pulchrum seeds. Seeds were buried in situ by the tunnelling species Copris victorini. Since seeds of both plant species attract several generalist dung beetles, this suggests that speciation in these two species has not been due to evolution for different or specific dispersers but may instead be related to exploitation of temporal niche opportunities.