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Intraspecific geographic variation of fragrances acquired by orchid bees in native and introduced populations.

Ramírez SR, Eltz T, Fritzsch F, Pemberton R, Pringle EG, Tsutsui ND - J. Chem. Ecol. (2010)

Bottom Line: We recorded a total of 292 fragrance compounds from hind-leg extracts, and found that overall perfume composition was different for each population.We detected a pronounced chemical dissimilarity between native (Mesoamerica) and naturalized (U.S.) populations that was driven both by proportional differences of common compounds as well as the presence of a few chemicals unique to each population group.By comparing incidence values and consistency indices across populations, we identify putative functional compounds that may play an important role in courtship signaling in this species of orchid bee.

View Article: PubMed Central - PubMed

Affiliation: Environmental Science, Policy & Management, University of California Berkeley, 137 Mulford Hall #3114, Berkeley, CA 94720, USA. sramirez77@berkeley.edu

ABSTRACT
Male orchid bees collect volatiles, from both floral and non-floral sources, that they expose as pheromone analogues (perfumes) during courtship display. The chemical profile of these perfumes, which includes terpenes and aromatic compounds, is both species-specific and divergent among closely related lineages. Thus, fragrance composition is thought to play an important role in prezygotic reproductive isolation in euglossine bees. However, because orchid bees acquire fragrances entirely from exogenous sources, the chemical composition of male perfumes is prone to variation due to environmental heterogeneity across habitats. We used Gas Chromatography/Mass Spectrometry (GC/MS) to characterize the perfumes of 114 individuals of the green orchid bee (Euglossa aff. viridissima) sampled from five native populations in Mesoamerica and two naturalized populations in the southeastern United States. We recorded a total of 292 fragrance compounds from hind-leg extracts, and found that overall perfume composition was different for each population. We detected a pronounced chemical dissimilarity between native (Mesoamerica) and naturalized (U.S.) populations that was driven both by proportional differences of common compounds as well as the presence of a few chemicals unique to each population group. Despite these differences, our data also revealed remarkable qualitative consistency in the presence of several major fragrance compounds across distant populations from dissimilar habitats. In addition, we demonstrate that naturalized bees are attracted to and collect large quantities of triclopyr 2-butoxyethyl ester, the active ingredient of several commercially available herbicides. By comparing incidence values and consistency indices across populations, we identify putative functional compounds that may play an important role in courtship signaling in this species of orchid bee.

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Map of Mesoamerica and southern United States indicating sampling localities where male Euglossa aff. viridissima were collected. Native range populations in Mesoamerica were El Chote, Monte Pio, El Remate, Xmatkuil and ACG. Naturalized populations in the United States were Gumbo-Limbo and Fern Forest
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Fig1: Map of Mesoamerica and southern United States indicating sampling localities where male Euglossa aff. viridissima were collected. Native range populations in Mesoamerica were El Chote, Monte Pio, El Remate, Xmatkuil and ACG. Naturalized populations in the United States were Gumbo-Limbo and Fern Forest

Mentions: The green orchid bee Euglossa viridissima is distributed throughout lowland dry forests in northern Mesoamerica (Hinojosa-Diaz et al., 2009), ranging in distribution from southern Costa Rica to Northern Mexico (Fig. 1). Previous taxonomic treatments recognized E. viridissima as a single distinct species (e.g., Roubik and Hanson, 2004). However, a recent study of populations from the Yucatan peninsula (Mexico) showed instead that this lineage consists of two cryptic sister species (Eltz et al., 2008). The most prominent morphological difference between the two lineages is in the number of teeth on the mandible of males: two or three dentitions. Additionally, whereas males with three dentitions (hereafter E. aff. viridissima) collect large quantities of the compound 2-hydroxy-6-nona-1,3-dienyl-benzaldehyde (abbreviated HNDB), males with two dentitions (E. viridissima) lack HNDB in their perfumes (Eltz et al., 2008). A detailed systematic analysis of these lineages based on morphology, chemistry, and genetic data is in preparation (Eltz et al., unpublished).Fig. 1


Intraspecific geographic variation of fragrances acquired by orchid bees in native and introduced populations.

Ramírez SR, Eltz T, Fritzsch F, Pemberton R, Pringle EG, Tsutsui ND - J. Chem. Ecol. (2010)

Map of Mesoamerica and southern United States indicating sampling localities where male Euglossa aff. viridissima were collected. Native range populations in Mesoamerica were El Chote, Monte Pio, El Remate, Xmatkuil and ACG. Naturalized populations in the United States were Gumbo-Limbo and Fern Forest
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2908462&req=5

Fig1: Map of Mesoamerica and southern United States indicating sampling localities where male Euglossa aff. viridissima were collected. Native range populations in Mesoamerica were El Chote, Monte Pio, El Remate, Xmatkuil and ACG. Naturalized populations in the United States were Gumbo-Limbo and Fern Forest
Mentions: The green orchid bee Euglossa viridissima is distributed throughout lowland dry forests in northern Mesoamerica (Hinojosa-Diaz et al., 2009), ranging in distribution from southern Costa Rica to Northern Mexico (Fig. 1). Previous taxonomic treatments recognized E. viridissima as a single distinct species (e.g., Roubik and Hanson, 2004). However, a recent study of populations from the Yucatan peninsula (Mexico) showed instead that this lineage consists of two cryptic sister species (Eltz et al., 2008). The most prominent morphological difference between the two lineages is in the number of teeth on the mandible of males: two or three dentitions. Additionally, whereas males with three dentitions (hereafter E. aff. viridissima) collect large quantities of the compound 2-hydroxy-6-nona-1,3-dienyl-benzaldehyde (abbreviated HNDB), males with two dentitions (E. viridissima) lack HNDB in their perfumes (Eltz et al., 2008). A detailed systematic analysis of these lineages based on morphology, chemistry, and genetic data is in preparation (Eltz et al., unpublished).Fig. 1

Bottom Line: We recorded a total of 292 fragrance compounds from hind-leg extracts, and found that overall perfume composition was different for each population.We detected a pronounced chemical dissimilarity between native (Mesoamerica) and naturalized (U.S.) populations that was driven both by proportional differences of common compounds as well as the presence of a few chemicals unique to each population group.By comparing incidence values and consistency indices across populations, we identify putative functional compounds that may play an important role in courtship signaling in this species of orchid bee.

View Article: PubMed Central - PubMed

Affiliation: Environmental Science, Policy & Management, University of California Berkeley, 137 Mulford Hall #3114, Berkeley, CA 94720, USA. sramirez77@berkeley.edu

ABSTRACT
Male orchid bees collect volatiles, from both floral and non-floral sources, that they expose as pheromone analogues (perfumes) during courtship display. The chemical profile of these perfumes, which includes terpenes and aromatic compounds, is both species-specific and divergent among closely related lineages. Thus, fragrance composition is thought to play an important role in prezygotic reproductive isolation in euglossine bees. However, because orchid bees acquire fragrances entirely from exogenous sources, the chemical composition of male perfumes is prone to variation due to environmental heterogeneity across habitats. We used Gas Chromatography/Mass Spectrometry (GC/MS) to characterize the perfumes of 114 individuals of the green orchid bee (Euglossa aff. viridissima) sampled from five native populations in Mesoamerica and two naturalized populations in the southeastern United States. We recorded a total of 292 fragrance compounds from hind-leg extracts, and found that overall perfume composition was different for each population. We detected a pronounced chemical dissimilarity between native (Mesoamerica) and naturalized (U.S.) populations that was driven both by proportional differences of common compounds as well as the presence of a few chemicals unique to each population group. Despite these differences, our data also revealed remarkable qualitative consistency in the presence of several major fragrance compounds across distant populations from dissimilar habitats. In addition, we demonstrate that naturalized bees are attracted to and collect large quantities of triclopyr 2-butoxyethyl ester, the active ingredient of several commercially available herbicides. By comparing incidence values and consistency indices across populations, we identify putative functional compounds that may play an important role in courtship signaling in this species of orchid bee.

Show MeSH