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Abstract Detail



Botany 2015 Colloquium: Integrated perspectives on the ecology, genetics and coevolution of intimate mutualisms

Hembry, David [1].

Diversification of the brood pollination mutualism between leafflower trees (Phyllanthus s. l. [Glochidion]) and leafflower moths (Epicephala) on oceanic islands.

Brood pollination mutualisms, in which specialized insect taxa act both as pollinators and seed predators of their host plants, are classically thought to be interactions in which coevolution drives ongoing specialization and diversification. Aside from yuccas and yucca moths, the mechanisms by which diversification has occurred in these mutualisms are unknown. Here, we examine the co-radiation of endemic leafflower trees (c. 25 spp.; Phyllanthus s. l. [Glochidion]) and their pollinating seed-predatory leafflower moths (Epicephala) across oceanic islands in southeastern Polynesia (central South Pacific). This represents a mutualism of tropical Asian/Australasian origin which has diversified across a set of young, oceanic archipelagos with discrete geology. Examining the diversification of these intimately interacting clades in this island biogeography framework allows us to test a number of hypotheses about how brood pollination mutualisms diversify. We find that Glochidion and Epicephala have not diversified via a process that produces phylogenetic congruence, but rather that rapid and widespread host-shifts have been important in this diversification. Allopatric isolation has clearly played a role in the divergence of Epicephala pollinators. Glochidion trees have at least in part diversified along ecological axes and show some interspecific variation in floral odor, a trait which in Asia mediates species-specificity between these taxa. Finally, patterns of specialization (network structure) in this interaction is not one-to-one as has been argued from continental regions, but shows reduced reciprocal specialization and low modularity, with many instances of plant species sharing the same pollinator and vice versa. These findings that despite the high potential for high specialization and co-adaptation in this mutualism, patterns of interaction between lineages in these two clades can be highly dynamic over short evolutionary timescales (<5 Ma). Current work examines whether and in what regions of the genome Epicephala moths are undergoing divergence associated with their plant host species, and whether this divergence may lead to incipient speciation.


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1 - University of California, Berkeley, California Institute for Quantitative Biosciences, Eisen Lab, 378 Stanley Hall #3220, Berkeley, CA, 94720-3220, USA

Keywords:
coevolution
mutualism
brood pollination
leafflower
Phyllanthaceae
host-shift
ecological network
island biogeography
Specialization.

Presentation Type: Colloquium Presentations
Session: C4
Location: Hall C/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 4:00 PM
Number: C4010
Abstract ID:626
Candidate for Awards:None


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