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Relative role of flower color and scent on pollinator attraction: experimental tests using F1 and F2 hybrids of daylily and nightlily.

Hirota SK, Nitta K, Kim Y, Kato A, Kawakubo N, Yasumoto AA, Yahara T - PLoS ONE (2012)

Bottom Line: Swallowtail butterflies preferentially visited reddish or orange-colored flowers and hawkmoths preferentially visited yellowish flowers.Neither swallowtail butterflies nor nocturnal hawkmoths showed significant preferences for overall scent emission.Our results suggest that mutations in flower color would be more relevant to the adaptive shift from a diurnally flowering ancestor to H. citrina than that in floral scent.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan.

ABSTRACT
The daylily (Hemerocallis fulva) and nightlily (H. citrina) are typical examples of a butterfly-pollination system and a hawkmoth-pollination system, respectively. H. fulva has diurnal, reddish or orange-colored flowers and is mainly pollinated by diurnal swallowtail butterflies. H. citrina has nocturnal, yellowish flowers with a sweet fragrance and is pollinated by nocturnal hawkmoths. We evaluated the relative roles of flower color and scent on the evolutionary shift from a diurnally flowering ancestor to H. citrina. We conducted a series of experiments that mimic situations in which mutants differing in either flower color, floral scent or both appeared in a diurnally flowering population. An experimental array of 6 × 6 potted plants, mixed with 24 plants of H. fulva and 12 plants of either F1 or F2 hybrids, were placed in the field, and visitations of swallowtail butterflies and nocturnal hawkmoths were recorded with camcorders. Swallowtail butterflies preferentially visited reddish or orange-colored flowers and hawkmoths preferentially visited yellowish flowers. Neither swallowtail butterflies nor nocturnal hawkmoths showed significant preferences for overall scent emission. Our results suggest that mutations in flower color would be more relevant to the adaptive shift from a diurnally flowering ancestor to H. citrina than that in floral scent.

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Typical reflectance spectra of F2 hybrids (above) and the relationship score, reflectance (below).(A) Reflectance spectra of the central part of tepals. Three representative F2 hybrids, DG11 (SCC=3), BD3 (SCC=13) and BC12 (SCC=21), are showed. (B) Reflectance spectra of the peripheral part of tepals. (C) The relationship between color chart score and relative reflectance at 525 nm of the central part of tepals. (D) The relationship between color chart score and relative reflectance at 360 nm of the peripheral part of tepals.
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pone-0039010-g004: Typical reflectance spectra of F2 hybrids (above) and the relationship score, reflectance (below).(A) Reflectance spectra of the central part of tepals. Three representative F2 hybrids, DG11 (SCC=3), BD3 (SCC=13) and BC12 (SCC=21), are showed. (B) Reflectance spectra of the peripheral part of tepals. (C) The relationship between color chart score and relative reflectance at 525 nm of the central part of tepals. (D) The relationship between color chart score and relative reflectance at 360 nm of the peripheral part of tepals.

Mentions: The flower color of H. fulva was reddish-orange and qualified with the standard color chart (SCC) as SCC 21-23 (Fig. 1A). The flower of F1 hybrids was yellow, qualified between SCC 11-15, and was therefore more yellowish than H. fulva (Fig.1B, Fig. 2A), but more orange-colored than H. citrina (SCC 3–4, Fig. 1C). The reflectance spectra shown in Fig. 3 (3A, central part of tepals; 3B, peripheral part; upper, H. citrina; center F1 hybrid; lower, H. fulva) differed notably between the two species at 525 nm corresponding to the peak sensitivity of the green receptor of butterflies and moths (Papilio xuthus: 520 nm, [27], Deilephila elpenor: 520–525 nm, [28], [29], Manduca sexta: 520 nm, [30]). The reflectance spectra of the color chart SCC 3, 13 and 23 largely differed at 525 nm. The reflectance spectra of the peripheral part of tepals largely differed also at 360 nm, corresponding to the peak sensitivity of the UV receptor of butterflies and moths (P. xuthus: 360 nm, [27], D. elpenor: 345–350 nm, [28], [29], M. sexta: 357 nm, [30]). This difference is not significant in the central part because tepals of Hemerocallis have a nectar guide in the central part that absorbs ultraviolet light. F2 hybrids showed high variability in flower color (SCC 3–23; Fig. 1D,E, F, Fig. 2B). Fig. 4A, B shows three typical reflectance spectra of F2 hybrids, DG11, BD3, BC12, qualified as SCC 3, 13, and 21, respectively. The reflectance at 525 nm (y) was correlated with SCC scores (x) as y=–1.73x+49.43 (P<0.001; Fig 4C), and the reflectance at 360 nm was also correlated with SCC scores as y=–1.10x+35.20 (P<0.001, Fig. 4D). However, the latter correlation was more dispersed than the former, and SCC scores mostly reflect the difference of the reflectance at 525 nm.


Relative role of flower color and scent on pollinator attraction: experimental tests using F1 and F2 hybrids of daylily and nightlily.

Hirota SK, Nitta K, Kim Y, Kato A, Kawakubo N, Yasumoto AA, Yahara T - PLoS ONE (2012)

Typical reflectance spectra of F2 hybrids (above) and the relationship score, reflectance (below).(A) Reflectance spectra of the central part of tepals. Three representative F2 hybrids, DG11 (SCC=3), BD3 (SCC=13) and BC12 (SCC=21), are showed. (B) Reflectance spectra of the peripheral part of tepals. (C) The relationship between color chart score and relative reflectance at 525 nm of the central part of tepals. (D) The relationship between color chart score and relative reflectance at 360 nm of the peripheral part of tepals.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3376114&req=5

pone-0039010-g004: Typical reflectance spectra of F2 hybrids (above) and the relationship score, reflectance (below).(A) Reflectance spectra of the central part of tepals. Three representative F2 hybrids, DG11 (SCC=3), BD3 (SCC=13) and BC12 (SCC=21), are showed. (B) Reflectance spectra of the peripheral part of tepals. (C) The relationship between color chart score and relative reflectance at 525 nm of the central part of tepals. (D) The relationship between color chart score and relative reflectance at 360 nm of the peripheral part of tepals.
Mentions: The flower color of H. fulva was reddish-orange and qualified with the standard color chart (SCC) as SCC 21-23 (Fig. 1A). The flower of F1 hybrids was yellow, qualified between SCC 11-15, and was therefore more yellowish than H. fulva (Fig.1B, Fig. 2A), but more orange-colored than H. citrina (SCC 3–4, Fig. 1C). The reflectance spectra shown in Fig. 3 (3A, central part of tepals; 3B, peripheral part; upper, H. citrina; center F1 hybrid; lower, H. fulva) differed notably between the two species at 525 nm corresponding to the peak sensitivity of the green receptor of butterflies and moths (Papilio xuthus: 520 nm, [27], Deilephila elpenor: 520–525 nm, [28], [29], Manduca sexta: 520 nm, [30]). The reflectance spectra of the color chart SCC 3, 13 and 23 largely differed at 525 nm. The reflectance spectra of the peripheral part of tepals largely differed also at 360 nm, corresponding to the peak sensitivity of the UV receptor of butterflies and moths (P. xuthus: 360 nm, [27], D. elpenor: 345–350 nm, [28], [29], M. sexta: 357 nm, [30]). This difference is not significant in the central part because tepals of Hemerocallis have a nectar guide in the central part that absorbs ultraviolet light. F2 hybrids showed high variability in flower color (SCC 3–23; Fig. 1D,E, F, Fig. 2B). Fig. 4A, B shows three typical reflectance spectra of F2 hybrids, DG11, BD3, BC12, qualified as SCC 3, 13, and 21, respectively. The reflectance at 525 nm (y) was correlated with SCC scores (x) as y=–1.73x+49.43 (P<0.001; Fig 4C), and the reflectance at 360 nm was also correlated with SCC scores as y=–1.10x+35.20 (P<0.001, Fig. 4D). However, the latter correlation was more dispersed than the former, and SCC scores mostly reflect the difference of the reflectance at 525 nm.

Bottom Line: Swallowtail butterflies preferentially visited reddish or orange-colored flowers and hawkmoths preferentially visited yellowish flowers.Neither swallowtail butterflies nor nocturnal hawkmoths showed significant preferences for overall scent emission.Our results suggest that mutations in flower color would be more relevant to the adaptive shift from a diurnally flowering ancestor to H. citrina than that in floral scent.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan.

ABSTRACT
The daylily (Hemerocallis fulva) and nightlily (H. citrina) are typical examples of a butterfly-pollination system and a hawkmoth-pollination system, respectively. H. fulva has diurnal, reddish or orange-colored flowers and is mainly pollinated by diurnal swallowtail butterflies. H. citrina has nocturnal, yellowish flowers with a sweet fragrance and is pollinated by nocturnal hawkmoths. We evaluated the relative roles of flower color and scent on the evolutionary shift from a diurnally flowering ancestor to H. citrina. We conducted a series of experiments that mimic situations in which mutants differing in either flower color, floral scent or both appeared in a diurnally flowering population. An experimental array of 6 × 6 potted plants, mixed with 24 plants of H. fulva and 12 plants of either F1 or F2 hybrids, were placed in the field, and visitations of swallowtail butterflies and nocturnal hawkmoths were recorded with camcorders. Swallowtail butterflies preferentially visited reddish or orange-colored flowers and hawkmoths preferentially visited yellowish flowers. Neither swallowtail butterflies nor nocturnal hawkmoths showed significant preferences for overall scent emission. Our results suggest that mutations in flower color would be more relevant to the adaptive shift from a diurnally flowering ancestor to H. citrina than that in floral scent.

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