Abstract:
A total of 26 species of birds in 10 families took F. pertusa fruit. Visitors' identity, abundance, and importance (estimated by an index of the number of fruits removed) all varied among trees and over time for individual trees. Compared with its obligate, species-specific pollination mutualism, F. pertusa's highly variable interactions with its present-day disperser assemblage are less likely to be products of coevolution. -from Authors
Abstract:
The natural history of Anidarnes bicolor (Ashmead) Boucek (Hymenoptera: Agaonidae: Sycophaginae), a host-specific galler of the Florida strangling fig (Ficus aurea, Moraceae), is described. A. bicolor females oviposit through the outside of the globular fig inflorescence; offspring feed on sterile tissue within galls induced on the inner wall of fig. Oviposition coincides with entry of the pollinators (Pegoscapus mexicanus; Hymenoptera: Agaonidae: Agaoninae) into the fig, and does not interfere with pollination. Pollinator presence is in fact crucial to A. bicolor success, because unpollinated, galled figs are aborted by the tree. However, A. bicolor may nevertheless reduce pollinator success: maturation of pollinator offspring appears to be negatively affected by the developing A. bicolor galls. Although the composition of the wasp community associated with the native Florida figs is relatively well-known, this is one of the first studies of the natural history of one of the non-pollinator species.
PMID: 19287014;PMCID: PMC2701751;Abstract:
BACKGROUND AND AIMS: A deeper understanding of mutualism can be reached by studying systems with measurable costs and benefits. Most studies of this type focus on an unusual class of obligate, species-specific pollination mutualisms. The interaction between Datura wrightii (Solanaceae) and the hawkmoth Manduca sexta offers similar advantages but greater generality. Adult moths both nectar at and deposit eggs on the same plant; larvae are herbivorous. The antagonistic component of this interaction has been well studied. Here the role of M. sexta as a pollinator of D. wrightii, particularly in the context of this moth's frequent nectaring visits to the bat-pollinated plant Agave palmeri, is documented. METHODS: Hand-pollinations were used to determine breeding system and the reproductive consequences of mixed loads of A. palmeri and D. wrightii pollen. Plants and moths were caged overnight to assess whether nectaring visits led to fruit and seed set. Finally, pollen deposited on field-collected stigmas was identified, with a particular focus on documenting the presence of D. wrightii and A. palmeri grains. KEY RESULTS: Datura wrightii is highly self-compatible, and a visit that deposits either outcross or self pollen almost doubles fruit and seed set compared with unvisited flowers. Manduca sexta transferred enough pollen to produce fruit and seed sets comparable to hand-pollination treatments. Agave palmeri did not interfere with D. wrightii success: in the field, stigmas received almost pure D. wrightii pollen, and hand-addition of large quantities of A. palmeri pollen had no measurable effect on fruit and seed set. CONCLUSIONS: The floral visitation component of the D. wrightii-M. sexta interaction is indeed mutualistic. This finding is essential background to future development of this interaction as a model system for studying mutualism's costs and benefits. It is already proving valuable for dissecting third-species effects on the outcome of mutualism. Results indicate that M. sexta's heavy visitation to A. palmeri has no negative effect on the benefits conferred to D. wrightii. However, it can be predicted to augment M. sexta populations to the point where the costs of the interaction begin to exceed its benefits.
PMID: 11829358;Abstract:
We investigate the coevolution of time of flowering and time of pollinator emergence in an obligate association between a plant and an insect that both pollinates and parasitizes flowers. Numerical analysis shows that the system in general evolves towards a time of flowering different from the time favoured by the abiotic environment. The equilibrium towards which the system evolves is a local fitness maximum (an ESS) with respect to mutational variation in flowering time but, for the insect, it can be a local fitness minimum at which selection on mutational variation in the time of insect emergence is disruptive. A consequence of evolutionary convergence to a fitness minimum is that pollinators having an earlier phenology can coexist with pollinators having a later phenology. Since late emerging insects are more likely to encounter and oviposit within previously pollinated flowers, their effect on the plant is more exploitative, leading them to function as cheaters within the system. Thus, in the long term, pollinators and exploiters are likely to be found in stable coexistence in pollinating seed-parasite systems. © 2001 Academic Press.
