Dispersal of semi-fleshy fruits to rock crevices by a rock-restricted rodent

White, Joseph DM; Midgley, Jeremy J

Dispersal of semi-fleshy fruits to rock crevices by a rock-restricted rodent

Journal Article

2017

Journal Title

South African Journal of Science

Link to Journal

https://dx.doi.org/10.17159/sajs.2017/20170159

Department

Department of Biological Sciences

Faculty

Faculty of Science

Abstract

Seed dispersal allows successive generations of plants to be mobile in space and time. Heeria argentea’s unusual fruit and its ubiquity in extremely rocky habitats, suggests that this tree requires a specialist disperser. We therefore investigated the dispersal ecology of H. argentea and Hartogiella schinoides. We found M. namaquensis rapidly removed H. argentea and H. schinoides fruits, moving them short distances within and between rock outcrops, and consumed only the pericarps. Birds were observed consuming H. schinoides, but not H. argentea fruits, suggesting M. namaquensis is its sole, specialist disperser. Most H. argentea seeds (65%) with removed pericarps germinated successfully, while intact fruits did not. We show rock outcrops represent fire refugia, allowing H. argentea trees to grow to large sizes, with small stems and a co-occurring, wind-dispersed tree, Widdringtonia nodiflora found away from these sites. This rodent–tree mutualism is perhaps the clearest global example of directed dispersal and shows that these endemic trees are highly adapted for survival in the southwestern Cape habitat and are not tropical relicts.