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- Friberg, Magne, et al.
(författare)
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Extreme divergence in floral scent among woodland star species (Lithophragma spp.) pollinated by floral parasites
- 2013
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Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 111:4, s. 539-550
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Tidskriftsartikel (refereegranskat)abstract
- A current challenge in coevolutionary biology is to understand how suites of traits vary as coevolving lineages diverge. Floral scent is often a complex, variable trait that attracts a suite of generalized pollinators, but may be highly specific in plants specialized on attracting coevolved pollinating floral parasites. In this study, floral scent variation was investigated in four species of woodland stars (Lithophragma spp.) that share the same major pollinator (the moth Greya politella, a floral parasite). Three specific hypotheses were tested: (1) sharing the same specific major pollinator favours conservation of floral scent among close relatives; (2) selection favours private channels of rare compounds particularly aimed at the specialist pollinator; or (3) selection from rare, less-specialized co-pollinators mitigates the conservation of floral scent and occurrence of private channels. Dynamic headspace sampling and solid-phase microextraction were applied to greenhouse-grown plants from a common garden as well as to field samples from natural populations in a series of experiments aiming to disentangle the genetic and environmental basis of floral scent variation. Striking floral scent divergence was discovered among species. Only one of 69 compounds was shared among all four species. Scent variation was largely genetically based, because it was consistent across field and greenhouse treatments, and was not affected by visits from the pollinating floral parasite. The strong divergence in floral scents among Lithophragma species contrasts with the pattern of conserved floral scent composition found in other plant genera involved in mutualisms with pollinating floral parasites. Unlike some of these other obligate pollination mutualisms, Lithophragma plants in some populations are occasionally visited by generalist pollinators from other insect taxa. This additional complexity may contribute to the diversification in floral scent found among the Lithophragma species pollinated by Greya moths.
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| 2. |
- Friberg, Magne, et al.
(författare)
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Floral Scent Contributes to Interaction Specificity in Coevolving Plants and Their Insect Pollinators
- 2014
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Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 0098-0331 .- 1573-1561. ; 40:9, s. 955-965
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Tidskriftsartikel (refereegranskat)abstract
- Chemical defenses, repellents, and attractants are important shapers of species interactions. Chemical attractants could contribute to the divergence of coevolving plant-insect interactions, if pollinators are especially responsive to signals from the local plant species. We experimentally investigated patterns of daily floral scent production in three Lithophragma species (Saxifragaceae) that are geographically isolated and tested how scent divergence affects attraction of their major pollinator the floral parasitic moth Greya politella (Prodoxidae). These moths oviposit through the corolla while simultaneously pollinating the flower with pollen adhering to the abdomen. The complex and species-specific floral scent profiles were emitted in higher amounts during the day, when these day-flying moths are active. There was minimal divergence found in petal color, which is another potential floral attractant. Female moths responded most strongly to scent from their local host species in olfactometer bioassays, and were more likely to oviposit in, and thereby pollinate, their local host species in no-choice trials. The results suggest that floral scent is an important attractant in this interaction. Local specialization in the pollinator response to a highly specific plant chemistry, thus, has the potential to contribute importantly to patterns of interaction specificity among coevolving plants and highly specialized pollinators.
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| 3. |
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| 4. |
- Svensson, Glenn, et al.
(författare)
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Pollinator attraction to volatiles from virgin and pollinated host flowers in a yucca/moth obligate mutualism
- 2011
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Ingår i: Oikos. - : Wiley. - 1600-0706 .- 0030-1299. ; 120:Published online 22 March, s. 1577-1583
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Tidskriftsartikel (refereegranskat)abstract
- The classic obligate pollination–seed consumption mutualism between yuccas and yucca moths has been thought to be mediated by chemical cues, but empirical data on pollinator attraction to host floral volatiles in this association have been lacking. Here we show that the scent from virgin flowers of the host Yucca glauca is sufficient to attract its obligate pollinator Tegeticula yuccasella in Y-tube olfactometer tests. Interestingly, both sexes of moths were attracted to the scent stimulus. Because yucca moths mate inside host flowers, the attraction of both females and males to host floral volatiles is likely to increase encounter rates. In a second test, female moths did not discriminate between virgin and hand-pollinated flowers, indicating no post-pollination change in scent production by the host that would lead to a reduction in pollinator attraction and thereby limit exploitation of the available seeds in host flowers. However, other mechanisms that could stabilise the mutualism between T. yuccasella and its yucca hosts have already been documented, i.e. selective abortion of heavily infested flowers, and a female-derived host-marking pheromone. Headspace collection and GC–MS were used to identify the blend of floral volatiles emitted by Y. glauca, which was found to be very similar to those of two other allopatric capsular-fruited species, Y. elata and Y. filamentosa, revealing strong conservation of this trait within Yucca section Chaenocarpa.
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