Fruit traits of vertebrate-dispersed alien plants: smaller seeds and more pulp sugar than indigenous species

Abstract

Vertebrates play a major role in dispersing seeds of fleshy-fruited alien plants. However, we know little of how the traits of alien fleshy fruits compare with indigenous fleshy fruits, and how these differences might contribute to invasion success. In this study, we characterised up to 38 fruit morphology, pulp nutrient and phenology traits of an assemblage of 34 vertebrate-dispersed alien species in south-eastern Queensland, Australia. Most alien fruits were small (81% \ 15 mm in mean width), and had watery fruit pulps that were high in sugars and low in nitrogen and lipids. When compared to indigenous species, alien fruits had significantly smaller seeds. Further, alien fruit pulps contained more sugar and more variable (and probably greater) nitrogen per pulp wet weight, and species tended to have longer fruiting seasons than indigenous species. Our analyses suggest that fruit traits could be important in determining invasiveness and could be used to improve pre-and post-border weed risk assessment.

Wahlberg’s epauletted fruit bat (Epomophorus wahlbergi) as a potential dispersal agent for fleshy-fruited invasive alien plants: effects of handling behaviour on seed germination

“…While each fruit may contain up to 570 seeds (Adsule and Kadam 1995), fruit from this study had c. 184 ± 26.64 seeds (mean ± SE, n = 10 fruit). Psidium guava escaped from commercially grown orchards though dispersal by native frugivorous birds and mammals (Samson 1986;Corlett 2005;Henderson 2007;Gosper and Vivian-Smith 2010). Melia azedarach fruits are also yellow when ripe and are c. 12 mm in diameter, becoming wrinkled as they ripen (Henderson 2001).…”

“…These fruits were originally grown for human consumption Invasive alien germination success following fruit bat processing 961 (Henderson 2001). While both birds and bats feed on these fruits (Gosper and Vivian-Smith 2010), these large seeds will most likely fall under the parent tree as a result of avian feeding. Morus alba fruit are purpleblack syncarps which are approximately 20 mm long (Henderson 2001) and each fruit from this study had 28.70 ± 4.82 seeds (n = 10 fruit).…”

“…Consequently these plants may benefit from greater fruit removal rates as this increases with decreasing distance to a neighbouring fruiting plant (Bach and Kelly 2004). Furthermore, numerous invasive alien fruit share characteristics with indigenous species (Gosper and Vivian-Smith 2010), fruit year round (Henderson 2001;Corlett 2005), and in some cases present fruits with greater nutritive value (Kueffer et al 2009;Gosper and Vivian-Smith 2010). Fruit bats are endotherms with high energetic demands for flight and so must feed optimally (Sánchez 2006).…”

The role of avian frugivores in germination of seeds of fleshy-fruited invasive alien plants

“…Invasive plant species that have the greatest impact on natural habitats are often trees or shrubs that are shade tolerant, grow rapidly, reproduce early, produce numerous seeds, and have fleshy fruits associated with bird-dispersal (Cronk and Fuller 1995). Recent studies highlight the importance of fruit traits associated with avian frugivore preferences, such as morphology (Gosper and Vivian-Smith 2009) and nutritional composition (Gosper and Vivian-Smith 2010).…”

Endozoochorous dispersal of alien and native plants by two palearctic avian frugivores with special emphasis on invasive giant goldenrod Solidago gigantea

“…Vertebrates, mainly birds, are thought to be very effective dispersal vectors of many alien species, but in most cases it was the dispersal of fleshy-fruited invasive plants that was studied [20,34,35]. We found diaspores of three alien species in droppings, two of which were fleshy-fruited (M. alba and V. lantana) and one was dry-fruited (S. gigantea).…”