Mascha Bischoff - Academia.edu (original) (raw)
Papers by Mascha Bischoff
Annals of botany, 2014
Floral traits, such as floral volatiles, can contribute to pre-zygotic reproductive isolation by ... more Floral traits, such as floral volatiles, can contribute to pre-zygotic reproductive isolation by promoting species-specific pollinator foraging. When hybrid zones form, floral traits could also influence post-zygotic isolation. This study examined floral volatiles in parental species and natural hybrids in order to explore potential scent mediation of pre-zygotic and post-zygotic isolation. Floral bouquets were analysed for the sister species Ipomopsis aggregata and I. tenuituba and their natural hybrids at two contact sites differing in both hybridization rate and temporal foraging pattern of hawkmoth pollinators. Floral volatiles were quantified in diurnal and nocturnal scent samples using gas chromatography-mass spectrometry. The bouquets of parental species and hybrids showed qualitative overlap. All flowers emitted similar sets of monoterpenoid, sesquiterpenoid, aliphatic and benzenoid compounds, but separated into groups defined by multivariate analysis of quantitative emissio...
Functional Ecology, 2013
1. Seed production in natural populations is often limited by quantity of pollen received. This p... more 1. Seed production in natural populations is often limited by quantity of pollen received. This pollen limitation has the potential to generate natural selection through female function favouring certain floral traits (hereafter 'pollen-mediated' selection). Floral traits can, however, also be under selection via other mechanisms, and the influence of a particular trait on pollen limitation of individuals is rarely quantified. 2. We took a trait-based approach to pollen limitation by adding a quantitative trait to a previously published model. The modified model predicted impacts of both pollen supplementation and pollen reduction in seed production when the trait influences pollen receipt, and when the trait influences other model parameters. We then manipulated pollen availability in a population of the alpine New Zealand herb Wahlenbergia albomarginata varying in petal colour to test a long-standing hypothesis that pale flower colour in that habitat is selected for via pollinators.
Ecology, 2010
Despite a long-standing belief that insect pollinators can select for certain flower colors, ther... more Despite a long-standing belief that insect pollinators can select for certain flower colors, there are few experimental demonstrations that free-flying insects choose between natural flowers based on color. We investigated responses of insect visitors to experimental manipulations of flower color in the New Zealand alpine. Native syrphid flies (Allograpta and Platycheirus) and solitary bees (Hylaeus and Leioproctus) showed distinct preferences for visiting certain flower species. These responses were determined, in part, by flower color, as insects also responded to experimental manipulations of visible petal color in 7 out of 11 tests with different combinations of flower species and insect type. When preferences were detected, syrphid flies chose yellow over white petals regardless of flower species, whereas Hylaeus chose white over yellow Ourisia glandulosa. In some cases, the strength and direction of color preference depended on the context of other floral traits, in which case the response usually favored the familiar, normal combination of traits. Syrphid flies also visited in response to floral morphological traits but did not show preference based on UV reflectance. The unusually high preponderance of white flowers in the New Zealand alpine is not explained by complete generalization of flower color choice. Instead, the insect visitors show preferences based on color, including colors other than white, along with other floral traits. Furthermore, they can respond in complex ways to combinations of floral cues, suggesting that traits may act in nonadditive ways in determining pollinator visitation.
Biochemical Systematics and Ecology, 2012
Evolution; international journal of organic evolution, 2015
Reproductive isolation due to pollinator behavior is considered a key mode of speciation in flowe... more Reproductive isolation due to pollinator behavior is considered a key mode of speciation in flowering plants. Although floral scent is thought to mediate pollinator behavior, little is known about its effects on pollinator attraction and floral visitation in the wild. We used field experiments with wild hawkmoths and laboratory experiments with naïve hawkmoths to investigate attraction to and probing of flowers in response to indole, a volatile emitted by Ipomopsis tenuituba but not its close relative I. aggregata, both alone and in combination with floral color differences. We demonstrated that indole attracts wild hawkmoths to flowers, but has little effect on the rate at which those attracted moths probe flowers. In contrast, white flower color did not influence hawkmoth attraction in the field, but caused more attracted moths to probe flowers. Thus, the moths require both scent and high visual contrast, in that order, to feed at flowers at dusk. Their preference for indole-scent...
Annals of botany, 2014
Floral traits, such as floral volatiles, can contribute to pre-zygotic reproductive isolation by ... more Floral traits, such as floral volatiles, can contribute to pre-zygotic reproductive isolation by promoting species-specific pollinator foraging. When hybrid zones form, floral traits could also influence post-zygotic isolation. This study examined floral volatiles in parental species and natural hybrids in order to explore potential scent mediation of pre-zygotic and post-zygotic isolation. Floral bouquets were analysed for the sister species Ipomopsis aggregata and I. tenuituba and their natural hybrids at two contact sites differing in both hybridization rate and temporal foraging pattern of hawkmoth pollinators. Floral volatiles were quantified in diurnal and nocturnal scent samples using gas chromatography-mass spectrometry. The bouquets of parental species and hybrids showed qualitative overlap. All flowers emitted similar sets of monoterpenoid, sesquiterpenoid, aliphatic and benzenoid compounds, but separated into groups defined by multivariate analysis of quantitative emissio...
Functional Ecology, 2013
1. Seed production in natural populations is often limited by quantity of pollen received. This p... more 1. Seed production in natural populations is often limited by quantity of pollen received. This pollen limitation has the potential to generate natural selection through female function favouring certain floral traits (hereafter 'pollen-mediated' selection). Floral traits can, however, also be under selection via other mechanisms, and the influence of a particular trait on pollen limitation of individuals is rarely quantified. 2. We took a trait-based approach to pollen limitation by adding a quantitative trait to a previously published model. The modified model predicted impacts of both pollen supplementation and pollen reduction in seed production when the trait influences pollen receipt, and when the trait influences other model parameters. We then manipulated pollen availability in a population of the alpine New Zealand herb Wahlenbergia albomarginata varying in petal colour to test a long-standing hypothesis that pale flower colour in that habitat is selected for via pollinators.
Ecology, 2010
Despite a long-standing belief that insect pollinators can select for certain flower colors, ther... more Despite a long-standing belief that insect pollinators can select for certain flower colors, there are few experimental demonstrations that free-flying insects choose between natural flowers based on color. We investigated responses of insect visitors to experimental manipulations of flower color in the New Zealand alpine. Native syrphid flies (Allograpta and Platycheirus) and solitary bees (Hylaeus and Leioproctus) showed distinct preferences for visiting certain flower species. These responses were determined, in part, by flower color, as insects also responded to experimental manipulations of visible petal color in 7 out of 11 tests with different combinations of flower species and insect type. When preferences were detected, syrphid flies chose yellow over white petals regardless of flower species, whereas Hylaeus chose white over yellow Ourisia glandulosa. In some cases, the strength and direction of color preference depended on the context of other floral traits, in which case the response usually favored the familiar, normal combination of traits. Syrphid flies also visited in response to floral morphological traits but did not show preference based on UV reflectance. The unusually high preponderance of white flowers in the New Zealand alpine is not explained by complete generalization of flower color choice. Instead, the insect visitors show preferences based on color, including colors other than white, along with other floral traits. Furthermore, they can respond in complex ways to combinations of floral cues, suggesting that traits may act in nonadditive ways in determining pollinator visitation.
Biochemical Systematics and Ecology, 2012
Evolution; international journal of organic evolution, 2015
Reproductive isolation due to pollinator behavior is considered a key mode of speciation in flowe... more Reproductive isolation due to pollinator behavior is considered a key mode of speciation in flowering plants. Although floral scent is thought to mediate pollinator behavior, little is known about its effects on pollinator attraction and floral visitation in the wild. We used field experiments with wild hawkmoths and laboratory experiments with naïve hawkmoths to investigate attraction to and probing of flowers in response to indole, a volatile emitted by Ipomopsis tenuituba but not its close relative I. aggregata, both alone and in combination with floral color differences. We demonstrated that indole attracts wild hawkmoths to flowers, but has little effect on the rate at which those attracted moths probe flowers. In contrast, white flower color did not influence hawkmoth attraction in the field, but caused more attracted moths to probe flowers. Thus, the moths require both scent and high visual contrast, in that order, to feed at flowers at dusk. Their preference for indole-scent...