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The article presents a study which compared fertility in the presence versus the absence of pollinators for a global dataset of 1174 plant species by quantifying pollinator contribution to seed production. Topics discussed include estimated percentage of flowering plant species that would produce no seeds without pollinators, plants where pollinator contribution to plant reproduction is higher, and the potential of pollinator declines to reduce reproduction for most plant species.

Abstract: The ability to self-fertilise may promote invasiveness in plants by assuring reproduction when mate and pollinator availabilities are inadequate, provided that the benefit of increased fecundity via selfing is not outweighed by inbreeding depression. However, knowledge of breeding systems and inbreeding depression has been lacking for most introduced plants. In this study of the invasive Australian tree Acacia dealbata in its introduced range in South Africa, controlled pollination experiments indicated that the study population was at least partially self-compatible and had a high capacity for autonomous self-pollination. However, we found substantial inbreeding depression, with seeds per fruit, progeny survival and progeny growth being lower after self- than after cross-pollination. Progeny arising from self-pollination also had a higher frequency of certain traits – yellow colouration of leaves and pink or white colouration of stems – which were associated with lower rates of survival. High inbreeding depression in A. dealbata must detract from the reproductive assurance benefit of self-fertilisation, casting doubt on the hypothesis that self-fertilisation contributes to invasiveness in this species. As high inbreeding depression has also been reported in other self-compatible trees, future studies should elucidate whether self-fertilisation contributes to invasiveness of trees by assessing both reproductive assurance benefits and inbreeding depression costs over the lifetime of progeny. [Copyright &y& Elsevier]

Generalized pollination systems and autonomous self-fertilization are traits that have been linked with plant invasiveness. However, whether specialized pollination requirements pose a significant barrier to plant invasions is not yet clear. Likewise, the contribution of pollinators to the fecundity of facultatively self-pollinating invasive plant species is poorly understood. We addressed these issues using the self-compatible and autonomously self-pollinating Lilium formosanum, which also has large, showy flowers that are adapted for pollination by hawk moths. We investigated the pollination of this lily-which is indigenous to Taiwan-in KwaZulu-Natal, South Africa, where it is invasive. The long-tongued hawk moth Agrius convolvuli was identified as the primary pollinator on the basis of field observations, pollen load analysis, presence of lepidopteran scales on stigmas, and higher seed production in emasculated flowers exposed at night than in those exposed during the day. Remarkably, this moth is native to much of the Old World, including Taiwan and South Africa. Autonomous self-pollination resulted in seed production, but at a reduced level relative to the seed production of open- and hand-pollinated flowers, which was significant in one out of two populations examined. Thus, pollinators potentially contribute to invasion by increasing seed production and genetic variability through cross-pollination, although contributions of pollinators to seed set versus that of autonomous self-pollination may vary between populations. We conclude that specialized pollination requirements do not present a barrier to invasions when plants are specialized to pollinators or pollinator functional groups with very wide distributions. [ABSTRACT FROM AUTHOR]

Summary: The role of pollination in the success of invasive plants needs to be understood because invasives have substantial effects on species interactions and ecosystem functions. Previous research has shown both that reproduction of invasive plants is often pollen limited and that invasive plants can have high seed production, motivating the questions: How do invasive populations maintain reproductive success in spite of pollen limitation? What species traits moderate pollen limitation for invaders?We conducted a phylogenetic meta‐analysis with 68 invasive, 50 introduced noninvasive and 1931 native plant populations, across 1249 species.We found that invasive populations with generalist pollination or pollinator dependence were less pollen limited than natives, but invasives and introduced noninvasives did not differ. Invasive species produced 3× fewer ovules/flower and >250× more flowers per plant, compared with their native relatives. While these traits were negatively correlated, consistent with a tradeoff, this did not differ with invasion status.Invasive plants that produce many flowers and have floral generalisation are able to compensate for or avoid pollen limitation, potentially helping to explain the invaders' reproductive successes. [ABSTRACT FROM AUTHOR]