Progress in understanding pollination systems in New Zealand

Abstract

Pollination in New Zealand, an isolated oceanic archipelago in the Southern Hemisphere, has previously been characterised as having low rates of self-incompatibility and a lack of specialised pollination, as well as little pollinator dependence. These features have been interpreted as supportive of "Baker's Rule", which suggests that long-distance colonisation selects for breeding systems that do not require biparental mating. However, we show that recent studies of the angiosperm flora reveal sexual systems (sexual dimorphism, self-incompatibility, monoecy, dichogamy, and herkogamy) that usually involve a dependence on pollen vectors. The level of self-incompatibility in the flora, though still poorly known, should be regarded as moderate rather than unusually low (about 36% of hermaphrodite populations tested are strongly or partially self-incompatible), though many more species remain to be tested. As found elsewhere, incompatibility is higher in the trees and shrubs (around 80%) compared with herbs (21%). Moreover, high rates of autonomous selfing have been demonstrated empirically in only 21% of the self-compatible species, demonstrating that they are not regular selfers. The pollinator dependence that these features impose makes much of the flora vulnerable to declines in pollinator service. B04046; Online publication date 17 March 2005 Received 24 November 2004; accepted 8 February 2005Pollination systems in New Zealand have been characterised as unspecialised, imprecise entomophilous systems that correspond to the predominance of small white or pale flowers with dish or bowl shapes. We use a two-tiered conceptual framework incorporating a coarse-scale blossom class analysis and a finer scale syndrome concept analysis to assess the level of specialisation in plant-pollinator relationships of New Zealand. Within each of the syndromes is a continuum of blossom classes: open-, directed-, and closed-access. Highly specialised systems are found in closed-access blossoms but they are not common in New Zealand (e.g., Solanum, Carmichaelia, orchids, and mistletoes). Large directed-access blossoms are primarily associated with bird pollination but certain small entomophilous blossoms, called "knob" blossoms (Pseudopanax, Geniostoma), are also important for perching birds and may be considered ornithophilous. Bats and lizards play a minor role in pollination. Moth pollination is not well studied and may reveal cryptic specialisation based on scent. The majority of pollination systems in New Zealand correspond to the "small bee syndrome", which is a generalised bee-pollinated system common elsewhere and includes visits from flies and other diverse insects. Naturalised exotic bees may have both positive and negative effects on indigenous pollination systems and could play a significant role in invasive mutualisms in which some weeds are specialised to their services. Future research in New Zealand pollination and breeding systems needs to focus on endangered mutualisms, particularly in birds; on invasive mut...

The secret service – analysis of the available knowledge on moths as pollinators in New Zealand

“…This diversification, combined with the fact that the New Zealand flora has an unusually high proportion of plant species with small, pale-coloured flowers (Godley 1979;Lloyd 1985;Campbell et al 2010), has led to the longheld assumption that moth pollination might be particularly important in New Zealand (e.g. Thomson 1881Thomson , 1928Heine 1937;Burrows 1960;Primack 1978Primack , 1983Godley 1979;Lloyd 1985;Robertson 1989;Newstrom & Robertson 2005;Merrett et al 2007;Pattemore & Wilcove 2012;Pattemore & Anderson 2013;Gardner-Gee et al 2014). However, there are little quantitative data to support this assumption.…”

“…For example, Primack (1983) is often cited as providing experimental evidence of pollination interactions in New Zealand, but he made no attempt to determine whether the insects observed were actually carrying pollen on their body. Owing largely to observational studies of floral visitation such as those of Primack (1979Primack ( , 1983, New Zealand's pollination systems have been characterised as highly generalised with extensive pollinator sharing, and unpredictable and imprecise pollinator services (Thomson 1928;Primack 1978Primack , 1983Lloyd 1985;Newstrom & Robertson 2005;Ollerton et al 2009). However, detailed experimental work has revealed discriminating foraging patterns by native insects, differences in effectiveness among insect taxa and thus more floral specialisation than previously thought (Bischoff 2008;Campbell et al 2010;Bischoff et al 2013;Miller et al in review).…”

New World Origins of Southwest Pacific Gesneriaceae: Multiple Movements Across and Within the South Pacific

“…These shifts from morphologically ornithophilous syndromes to insect-or self-pollinated syndromes and from bilateral to radial symmetry are likely the result of pollinator selection. Lloyd (1985) noted that many New Zealand plants have small, pale flowers that he considered despecialized in relation to overseas relatives; he considered low pollinator numbers and unique pollinator assemblages (particularly a lack of long-tongued bees) as the basis for selection of the generalized pollination syndrome seen in many New Zealand flowers (but see Newstrom and Robertson 2005). Carpenter et al (2003) found a dominance of small, actinomorphic (often dishlike), white or pale-colored flowers in a study of 123 tropical tree species in New Caledonia and considered that the limited availability of specialist pollinators was a major factor in the selection for generalist flowers there.…”

Hybridization amongst New ZealandSchoenus(Cyperaceae)?

“…Studies of incompatibility using the Lundqvist (1961) petri dish technique as well as hand pollination on intact flowers revealed that all showed self pollen tube growth down to the base of the style and seed set on self-pollination. Thus, these Schoenus species can be added to the list of self-compatible New Zealand angiosperms adding support to the general consensus that self-incompatibility is relatively infrequent in the indigenous and endemic flora (Webb & Kelly 1993;Newstrom & Robertson 2005).…”