Seed traits and fate support probable primary dispersal of a native hemi-parasitic vine Cassytha pubescens (Lauraceae) by Isoodon obesulus, an endangered marsupial, in southern Australia

Abstract

ABSTRACT Consumption of seeds by fruit-eating animals is one of the most effective dispersal mechanisms for plants, yet little is known about dispersal by marsupial vectors. In the face of habitat fragmentation and the recent extinction or decline of many marsupial species in southern Australia, addressing knowledge gaps on vertebrate vectors is critical to determine deficiencies in seed dispersal. Here we examine one potential dispersal vector for the seeds of Cassytha pubescens, a native hemi-parasitic vine that contributes to vegetation complexity within many woodland habitats in southern Australia that are threatened by fragmentation. To determine the potential dispersal role of mammals for Cassytha pubescens within southern Australian woodlands, we collected and examined 46 scat samples from the omnivorous, nationally endangered southern brown bandicoot, Isoodon obesulus, over two fruiting (summer) seasons. Of the 46 scats, five had up to six seemingly undigested seeds of C. pubescens, indicating that I. obesulus consumes the fruits and may act as a disperser for this vine. Our findings improve understanding of the role of marsupials like bandicoots in dispersing native plant seed and may help to inform conservation management priorities to protect ecosystem function more effectively in fragmented woodlands threatened by loss of vertebrate seed vectors.