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- Title
Spatial heterogeneity, pollinator behaviour and pollinator-mediated gene flow: bumblebee movements in variously aggregated rows of oil-seed rape.
- Authors
Cresswell, J. E.
- Abstract
The foraging movements of bees are said to be influenced by the spatial distribution of the plants whose flowers they visit. However, Manasse found that bee-mediated gene flow was unrelated to the degree ofaggregation among the plants in the linear arrays that he studied. To investigate this apparent contradiction further, I manipulated the levels of aggregation in linear plant arrays and examined both the effect on the movements of the bumblebee pollinators and the likely consequences for pollen dispersal and gene flow. I studied pollinator movements among plants of oil-seed tape (Brassica napus cv. Westar) that were arranged in rows that each contained 50 plants. In each experiment one row of plants was spaced at uniform intervals and the remaining rows contained aggregated plant distributions. Experiments were conducted at two scales, short rows (10 m) and long rows (20 m). The plants were visited almost exclusively by worker caste individuals of Bombus lapidarius. Bumblebees were followed over successive visits within a row and the location of each visited plant and the number of flowers probed there was recorded. Within each row, I examined the following components of bumblebee behaviour: the mean number of flowers probed per plant visit; the mean interplant flight distance; and the mean directionality (proportion of moves in an individual's favoured direction). The collective movements of bumblebees within each row were characterised by the rate of change of the bees' mean squared distance from an original location. The spatial dispersion of pollen froma paternal plant was estimated in each row by combining a quantitative description of bumblebee movements in terms of displacement from apaternal plant with a model of pollen deposition. Bumblebees were observed to visit many plants successively within a row and movements between rows were infrequent. In both long and short rows, three components of bumblebee movement behaviour were significantly modified by the
- Subjects
PLANT ecology; INSECT behavior
- Publication
Oikos, 1997, Vol 78, Issue 3, p546
- ISSN
0030-1299
- Publication type
Article
- DOI
10.2307/3545616