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Tactical release of a sexually-selected pheromone in a swordtail fish.

Rosenthal GG, Fitzsimmons JN, Woods KU, Gerlach G, Fisher HS - PLoS ONE (2011)

Bottom Line: Swordtails (genus Xiphophorus) are widely used in studies of female mate choice, and female response to male chemical cues is important to sexual selection, reproductive isolation, and hybridization.We used fluorescein dye injections to visualize pulsed urine release in male sheepshead swordtails, Xiphophorus birchmanni.Males urinated more frequently in the presence and proximity of an audience (conspecific females).

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Texas A&M University, College Station, Texas, United States of America. grosenthal@bio.tamu.edu

ABSTRACT

Background: Chemical communication plays a critical role in sexual selection and speciation in fishes; however, it is generally assumed that most fish pheromones are passively released since most fishes lack specialized scent glands or scent-marking behavior. Swordtails (genus Xiphophorus) are widely used in studies of female mate choice, and female response to male chemical cues is important to sexual selection, reproductive isolation, and hybridization. However, it is unclear whether females are attending to passively produced cues, or to pheromones produced in the context of communication.

Methodology/principal findings: We used fluorescein dye injections to visualize pulsed urine release in male sheepshead swordtails, Xiphophorus birchmanni. Simultaneous-choice assays of mating preference showed that females attend to species- and sex-specific chemical cues emitted in male urine. Males urinated more frequently in the presence and proximity of an audience (conspecific females). In the wild, males preferentially courted upstream of females, facilitating transmission of pheromone cues.

Conclusions/significance: Males in a teleost fish have evolved sophisticated temporal and spatial control of pheromone release, comparable to that found in terrestrial animals. Pheromones are released specifically in a communicative context, and the timing and positioning of release favors efficient signal transmission.

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Related in: MedlinePlus

Males prefer to urinate near females.Mean (+ SE) number of male urine pulses per hour within 12.5 cm of the adjacent stimulus aquarium (closest: quadrant 1) and in the remaining 37.5 cm of the male's aquarium (other: quadrants 2–4) with females present and absence. p-values from Wilcoxon signed-ranks tests are shown.
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pone-0016994-g003: Males prefer to urinate near females.Mean (+ SE) number of male urine pulses per hour within 12.5 cm of the adjacent stimulus aquarium (closest: quadrant 1) and in the remaining 37.5 cm of the male's aquarium (other: quadrants 2–4) with females present and absence. p-values from Wilcoxon signed-ranks tests are shown.

Mentions: Males showed a substantial increase in urination rate when in the presence of females as opposed to when females were absent (WSR test: z = 2.073, n = 9, p = 0.038; Figure 3). This was driven by a marked increase in urination specifically when males were close to females. As expected, males spent much more time in quadrant 1, the area closest to females, when females were present in the adjacent stimulus tank (72% versus 39% when females were absent; WSR test: z = 2.666, n = 9, p = 0.008). When males were in quadrant 1, urination rate per unit time was significantly higher when females were present (WSR test: z = 2.547, n = 9, p = 0.011). Conversely, urination rates in the remaining quadrants were unaffected by the presence of females, and in fact the numerical trend was in the direction of more urinations when females were absent (WSR test: z = 1.244, n = 9, p = 0.214).


Tactical release of a sexually-selected pheromone in a swordtail fish.

Rosenthal GG, Fitzsimmons JN, Woods KU, Gerlach G, Fisher HS - PLoS ONE (2011)

Males prefer to urinate near females.Mean (+ SE) number of male urine pulses per hour within 12.5 cm of the adjacent stimulus aquarium (closest: quadrant 1) and in the remaining 37.5 cm of the male's aquarium (other: quadrants 2–4) with females present and absence. p-values from Wilcoxon signed-ranks tests are shown.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3037275&req=5

pone-0016994-g003: Males prefer to urinate near females.Mean (+ SE) number of male urine pulses per hour within 12.5 cm of the adjacent stimulus aquarium (closest: quadrant 1) and in the remaining 37.5 cm of the male's aquarium (other: quadrants 2–4) with females present and absence. p-values from Wilcoxon signed-ranks tests are shown.
Mentions: Males showed a substantial increase in urination rate when in the presence of females as opposed to when females were absent (WSR test: z = 2.073, n = 9, p = 0.038; Figure 3). This was driven by a marked increase in urination specifically when males were close to females. As expected, males spent much more time in quadrant 1, the area closest to females, when females were present in the adjacent stimulus tank (72% versus 39% when females were absent; WSR test: z = 2.666, n = 9, p = 0.008). When males were in quadrant 1, urination rate per unit time was significantly higher when females were present (WSR test: z = 2.547, n = 9, p = 0.011). Conversely, urination rates in the remaining quadrants were unaffected by the presence of females, and in fact the numerical trend was in the direction of more urinations when females were absent (WSR test: z = 1.244, n = 9, p = 0.214).

Bottom Line: Swordtails (genus Xiphophorus) are widely used in studies of female mate choice, and female response to male chemical cues is important to sexual selection, reproductive isolation, and hybridization.We used fluorescein dye injections to visualize pulsed urine release in male sheepshead swordtails, Xiphophorus birchmanni.Males urinated more frequently in the presence and proximity of an audience (conspecific females).

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Texas A&M University, College Station, Texas, United States of America. grosenthal@bio.tamu.edu

ABSTRACT

Background: Chemical communication plays a critical role in sexual selection and speciation in fishes; however, it is generally assumed that most fish pheromones are passively released since most fishes lack specialized scent glands or scent-marking behavior. Swordtails (genus Xiphophorus) are widely used in studies of female mate choice, and female response to male chemical cues is important to sexual selection, reproductive isolation, and hybridization. However, it is unclear whether females are attending to passively produced cues, or to pheromones produced in the context of communication.

Methodology/principal findings: We used fluorescein dye injections to visualize pulsed urine release in male sheepshead swordtails, Xiphophorus birchmanni. Simultaneous-choice assays of mating preference showed that females attend to species- and sex-specific chemical cues emitted in male urine. Males urinated more frequently in the presence and proximity of an audience (conspecific females). In the wild, males preferentially courted upstream of females, facilitating transmission of pheromone cues.

Conclusions/significance: Males in a teleost fish have evolved sophisticated temporal and spatial control of pheromone release, comparable to that found in terrestrial animals. Pheromones are released specifically in a communicative context, and the timing and positioning of release favors efficient signal transmission.

Show MeSH
Related in: MedlinePlus