Fly-by-Night Sex

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Science  04 Dec 2009:
Vol. 326, Issue 5958, pp. 1323
DOI: 10.1126/science.326.5958.1323-b
CREDIT: AHMED ET AL., PROC. NATL. ACAD. SCI. U.S.A. 106, 10.1073/PNAS.0902213106 (2009)

Fig trees are totally dependent on species-specific fig wasps that carry pollen between trees. The wasps are weak nocturnal fliers and live for only 2 days at most, and neighboring trees flower asynchronously, so species survival (of both tree and wasp) depends entirely on successful transits.

By physical mapping and genetic finger-printing, Ahmed et al. measured the gene flow in 79 fig trees along 250 km of the Ugab River in Namibia. Fruit was collected from individual trees and paternity was assigned to enable tracking of the insect pollinators; fig wasps were shown to move over distances as large as 160 km. Within this population, gene flow was predominantly unidirectional, suggesting that the insects were borne by the easterly winds. The authors conclude that the long-distance pollination of isolated individuals helps to maintain both the plant and insect populations and enables them to overcome the barrier effects of habitat fragmentation.

Proc. Natl. Acad. Sci. U.S.A. 106, 10.1073/pnas.0902213106 (2009).

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