SummaryThe aims of this paper were to consider the coevolution between bumblebee movement patterns within plants and various properties of the plants such as the spatial distribution of their flowers, and to determine the extent to which the bumblebees and the plants can be considered to be maximally adaptive or optimal. Attention was restricted to plants which have flowers arranged on vertical inflorescences and to the bumblebees which visit these plants.It was found that the bumblebees tend to commence foraging at the bottom of each infloresence, that they tend to move from one flower to the closest vertically higher flower, that they miss flowers as they move upwards and that they tend to leave each inflorescence before reaching the top. It was also found for the four common plant species considered that nectar abundance per flower decreases with flower height on an inflorescence, that the flowers with receptive stigmas are restricted to the bottoms of the inflorescences while the flowers shedding pollen occur above them, and that the flowers are arranged approximately in spirals on the inflorescences.The pattern of movements of the bumblebees and the various properties of the plants appear to represent coevolved adaptations. Furthermore the bumblebees' movement patterns appear to be optimal in the sense that they result in the maximum net rate of energy gain to the bumblebees. Further studies are necessary, however, to determine whether or not the plants can be considered to be optimal.An exception to the above scheme is provided by a plant which is quite uncommon in the study area. This plant also has flowers on vertical inflorescences and appears to be pollinated by bumblebees. However, while the pattern of movements of the bumblebees on this plant species are extremely similar to those on the four common species, this plant species exhibits quite different properties from the other four. Two possible explanations for this exception are presented.
[1]
H. Lewis,et al.
INCREASE OF THE ADAPTIVE RANGE OF THE GENUS DELPHINIUM
,
1952
.
[2]
B. Hocking,et al.
Insect-flower associations in the high Arctic with special reference to nectar'
,
1968
.
[3]
E. Charnov.
Optimal foraging, the marginal value theorem.
,
1976,
Theoretical population biology.
[4]
S. Stearns.
Life-History Tactics: A Review of the Ideas
,
1976,
The Quarterly Review of Biology.
[5]
P. Kevan.
Insect pollination of high Arctic flowers
,
1972
.
[6]
L. W. Macior.
POLLINATION ADAPTATION IN PEDICULARIS LANCEOLATA
,
1969
.
[7]
T. Schoener.
Theory of Feeding Strategies
,
1971
.
[8]
C. S. Holling.
The Analysis of Complex Population Processes
,
1964,
The Canadian Entomologist.
[9]
R. Cruden.
INTRASPECIFIC VARIATION IN POLLEN-OVULE RATIOS AND NECTAR SECRETION-PRELIMINARY EVIDENCE OF ECOTYPIC ADAPTATION'
,
1976
.
[10]
D J McFarland,et al.
The behavioural final common path.
,
1975,
Philosophical transactions of the Royal Society of London. Series B, Biological sciences.
[11]
Knut Faegri,et al.
The principles of pollination ecology
,
1967
.
[12]
G. Bidder.
The perfection of sponges.
,
1937
.
[13]
Bernd Heinrich,et al.
Energetics of Pollination
,
1975
.
[14]
V. Grant.
The Fertilization of Flowers
,
1951
.
[15]
Graham H. Pyke,et al.
Optimal Foraging: A Selective Review of Theory and Tests
,
1977,
The Quarterly Review of Biology.
[16]
G. Pyke.
Optimal foraging: movement patterns of bumblebees between inflorescences.
,
1978,
Theoretical population biology.