Putting pollination quality into analyses of floral ecology: testing syndromes through pollinator performance
View/ Open
Date
19/07/2012Author
Supervisor
Metadata
Show full item recordAltmetrics Handle Statistics
Abstract
Over recent years, the extent of specialised and generalised plant-pollinator
relationships, and the predictive powers of floral traits (often grouped into “pollination syndromes”) as indicators of the most effective pollinators of plant species, have been
questioned. Such studies, however, have used proxies such as visitation frequency rather
than direct measurements of pollinator effectiveness (PE). The main objective of this thesis
was to test the predictive powers of various pollination syndromes using a specific measure
of PE: single-visit stigmatic pollen deposition (SVSPD).
Six different classical pollination syndromes were tested, using 13 different plant
species from tropical and temperate habitats, and in the case of flowers typical of the
hummingbird, hoverfly, bee, oil flower and long-tongued insect syndromes, the expected
pollinators were the most effective at a single-visit scale. For generalist pollination syndrome
flowers, not all observed visitors were significant pollinators, and the species studied were
not as broadly generalised as their visitor assemblages would suggest.
In all 13 plant species, pollinator performance could appear consistent within
functional visitor groups but was variable between visitor species, and in almost all cases not
all of the observed visitors were effective pollinators. The pollinator performance proxies of
visit duration and feeding behaviour were neither significantly, nor consistently, related to
PE. Visit duration was not an accurate indicator of pollinator performance on its own, though
it was useful when combined with SVSPD to define pollinator performance at a given time
scale, for example per hour, per day or per season. My findings suggest that the results of
recent “pollination” networks and webs, based on visitors but not necessarily pollinators,
should be treated with caution.
SVSPD therefore proved to be an effective and relatively simple direct measure of
PE, confirming the predictive powers of pollination syndromes, and giving further insight into
the extent of specialisation and generalisation.
Type
Thesis, PhD Doctor of Philosophy
Collections
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.