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Sara M. Lewis - One of the best experts on this subject based on the ideXlab platform.
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Molecular characterization of firefly nuptial gifts: a multi-omics approach sheds light on postcopulatory sexual selection.
Scientific Reports, 2016Co-Authors: Nooria Al-wathiqui, Adam South, Timothy R. Fallon, Jing-ke Weng, Sara M. LewisAbstract:Postcopulatory sexual selection is recognized as a key driver of reproductive trait evolution, including the machinery required to produce endogenous nuptial gifts. Despite the importance of such gifts, the molecular composition of the non-gametic components of male ejaculates and their interactions with female reproductive tracts remain poorly understood. During mating, male Photinus fireflies transfer to females a spermatophore gift manufactured by multiple reproductive glands. Here we combined transcriptomics of both male and female reproductive glands with proteomics and metabolomics to better understand the synthesis, composition and fate of the spermatophore in the common Eastern firefly, Photinus pyralis. Our transcriptome of male glands revealed up-regulation of proteases that may enhance male fertilization success and activate female immune response. Using bottom-up proteomics we identified 208 functionally annotated proteins that males transfer to the female in their spermatophore. Targeted metabolomic analysis also provided the first evidence that Photinus nuptial gifts contain lucibufagin, a firefly defensive toxin. The reproductive tracts of female fireflies showed increased gene expression for several proteases that may be involved in egg production. This study offers new insights into the molecular composition of male spermatophores, and extends our understanding of how nuptial gifts may mediate postcopulatory interactions between the sexes.
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Modeling effects of harvest on firefly population persistence
Ecological Modelling, 2013Co-Authors: Carolyn M. Bauer, Sara M. Lewis, Gösta Nachman, Lynn Faust, J. Michael ReedAbstract:North American fireflies in the genus Photinus are commercially harvested to extract the enzyme luciferase, despite the availability of a synthetic recombinant enzyme. Our goal was to examine the potential effects of harvesting on Photinus population persistence. Using estimated demographic parameters for Photinus, we developed a stochastic simulation population model to understand combined effects of demography, harvest rate, delayed larval development, and environmental stochasticity on population persistence of fireflies. With no harvest and low environmental stochasticity, modeled populations tended to reach carrying capacity. We found that average population size of adult fireflies decreased with increasing harvest rate and increasing environmental stochasticity. At the highest modeled growth rate (λ=2.8) the population failed to persist only when environmental stochasticity was high and harvest rate was ≥60%. Once harvest was introduced, only populations with high growth rates consistently persisted. Long-term, sustainable Photinus harvest rates based on survey data suggest that harvest rates >10% are acceptable only if λ>1.6. Our modeling results suggest that Photinus populations might tolerate low harvest levels, although in the absence of more precise data on vital rates and the amount of environmental stochasticity, the exact level is unknown. To further examine sustainability, harvest rates should be monitored and standardized surveys conducted to document firefly population changes.
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Determinants of reproductive success across sequential episodes of sexual selection in a firefly
Proceedings of The Royal Society B: Biological Sciences, 2012Co-Authors: Adam South, Sara M. LewisAbstract:Because females often mate with multiple males, it is critical to expand our view of sexual selection to encompass pre-, peri- and post-copulatory episodes to understand how selection drives trait evolution. In Photinus fireflies, females preferentially respond to males based on their bioluminescent courtship signals, but previous work has shown that male paternity success is negatively correlated with flash attractiveness. Here, we experimentally manipulated both the attractiveness of the courtship signal visible to female Photinus greeni fireflies before mating and male nuptial gift size to determine how these traits might each influence mate acceptance and paternity share. We also measured pericopulatory behaviours to examine their influence on male reproductive success. Firefly males with larger spermatophores experienced dual benefits in terms of both higher mate acceptance and increased paternity share. We found no effect of courtship signal attractiveness or pericopulatory behaviour on male reproductive success. Taken together with previous results, this suggests a possible trade-off for males between producing an attractive courtship signal and investing in nuptial gifts. By integrating multiple episodes of sexual selection, this study extends our understanding of sexual selection in Photinus fireflies and provides insight into the evolution of male traits in other polyandrous species.
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assessing condition dependence of male flash signals in Photinus fireflies
Journal of Insect Behavior, 2010Co-Authors: Evelyn K Sharkey, Christopher K Cratsley, Paul R. Moosman, Adam South, Sara M. LewisAbstract:Females often show a preference for exaggerated male sexual traits or courtship behaviors. Such preferences can benefit females if trait expression is correlated with male genetic quality or phenotypic condition. Previous studies of several Photinus fireflies have revealed considerable intraspecific variation in the bioluminescent courtship signals emitted by males, and have also demonstrated that females prefer more conspicuous male signals. Thus, females might gain information about male phenotypic quality if courtship signals reflect male condition. We examined possible condition-dependence of Photinus male courtship signals using two complementary approaches. First we experimentally manipulated male mating status, which is expected to affect male condition by depleting resources required for nuptial gift formation, and looked at how individual male flash signals changed with mating status and over time. We used an additional approach to assess condition-dependence by examining whether a relationship exists between flash signal parameters and measures of male condition and body shape. We found that the pulse rate of P. greeni courtship signals was not altered by male mating status or age, and that the pulse duration of P. ignitus signals was also not affected by male mating status. In P. pyralis fireflies, males showed a non-significant trend toward reduced signal pulse duration with age. When we examined the relationship between male flash signals and condition measures, we found no effect of male condition or body shape on courtship signals in P. greeni or P. ignitus; in P. pyralis, males with wider body shapes produced longer duration flash signals. On the other hand, we found no evidence in P. pyralis that condition predicted flash duration. Taken together, these results indicate that Photinus males’ flash signals do not reflect adult male condition, and suggest that females are unlikely to use courtship signals as an indicator of male phenotypic quality.
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Male reproductive allocation in fireflies (Photinus spp.)
Invertebrate Biology, 2007Co-Authors: Kristian C. Demary, Sara M. LewisAbstract:Resource allocation between somatic and reproductive structures has important fitness consequences for individuals, and optimal trade-offs are expected to depend not only on mating system differences among species but also on levels of resource stress within species. We tested the prediction that polyandry ( associated with increased sperm competition) will increase male reproductive allocation in bioluminescent fireflies in Photinus spp. by comparing the relative mass of testes, seminal vesicles, and reproductive accessory glands among a monandrous and several polyandrous species. In addition, we examined a single population of a polyandrous species, Photinus greeni, to see how reproductive allocation might shift between years in response to different levels of larval resource stress. As predicted, males of P. collustrans, a monandrous species, showed a fivefold lower allocation to sperm production and a 100-fold lower allocation to reproductive accessory glands compared with males from polyandrous species. We also found evidence within P. greeni of a trade-off between allocation either to reproduction or to somatic tissue; following larval resource stress, males eclosed at significantly shorter body lengths, yet showed a 35% increase in their reproductive allocation. These results demonstrate that mating systems strongly influence male allocation to reproductive accessory glands as well as to sperm production. Furthermore, these results suggest that under larval resource stress males of Photinus spp. increase their allocation to reproduction at the expense of somatic tissue, thus maximizing their ability to produce nuptial gifts required for reproductive success.
Kristian C. Demary - One of the best experts on this subject based on the ideXlab platform.
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Male reproductive allocation in fireflies (Photinus spp.)
Invertebrate Biology, 2007Co-Authors: Kristian C. Demary, Sara M. LewisAbstract:Resource allocation between somatic and reproductive structures has important fitness consequences for individuals, and optimal trade-offs are expected to depend not only on mating system differences among species but also on levels of resource stress within species. We tested the prediction that polyandry ( associated with increased sperm competition) will increase male reproductive allocation in bioluminescent fireflies in Photinus spp. by comparing the relative mass of testes, seminal vesicles, and reproductive accessory glands among a monandrous and several polyandrous species. In addition, we examined a single population of a polyandrous species, Photinus greeni, to see how reproductive allocation might shift between years in response to different levels of larval resource stress. As predicted, males of P. collustrans, a monandrous species, showed a fivefold lower allocation to sperm production and a 100-fold lower allocation to reproductive accessory glands compared with males from polyandrous species. We also found evidence within P. greeni of a trade-off between allocation either to reproduction or to somatic tissue; following larval resource stress, males eclosed at significantly shorter body lengths, yet showed a 35% increase in their reproductive allocation. These results demonstrate that mating systems strongly influence male allocation to reproductive accessory glands as well as to sperm production. Furthermore, these results suggest that under larval resource stress males of Photinus spp. increase their allocation to reproduction at the expense of somatic tissue, thus maximizing their ability to produce nuptial gifts required for reproductive success.
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Male courtship attractiveness and paternity success in Photinus greeni fireflies
Evolution, 2007Co-Authors: Kristian C. Demary, Sara M. LewisAbstract:Although female mate choice and male sperm competition have separately attracted much attention, few studies have addressed how precopulatory and postcopulatory episodes of sexual selection might interact to drive the evolution of male traits. In Photinus fireflies, females preferentially respond to males based on their bioluminescent courtship signals, and females gain direct benefits through male nuptial gifts acquired during multiple matings over several nights. We experimentally manipulated matings of P. greeni fireflies to test the hypothesis that postcopulatory paternity success might be biased toward males that are more attractive during courtship interactions. We first measured male courtship attractiveness to individual females using field behavioral assays. Females were then assigned to two double-mating treatments: (1) least attractive second male-females were first mated with their most attractive male, followed by their least attractive male, or (2) most attractive second male-females mated with males in reverse order. Larval offspring produced by each female following these double matings were genotyped using random amplified polymorphic DNA (RAPD) markers, and male paternity was determined. Contrary to prediction, firefly males that were more attractive to females based on their bioluminescent courtship displays subsequently showed significantly lower paternity, reflecting possible male trade-offs or sexual conflict. Differences in male paternity were not related to male body condition, testes or accessory gland mass, or to variation in female spermathecal size. Additionally, this study suggests that changes in phenotypic selection gradients may occur during different reproductive stages. These results indicate that it is crucial for future studies on sexual selection in polyandrous species to integrate both precopulatory and postcopulatory episodes to fully understand the evolution of male traits.
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Male courtship signals and female signal assessment in Photinus greeni fireflies
Behavioral Ecology, 2006Co-Authors: Constantinos I. Michaelidis, Kristian C. Demary, Sara M. LewisAbstract:The evolutionary dynamic of courtship signaling systems is driven by the interaction between male trait distributions and female preferences. This interaction is complex because females may choose mates based on multiple components of male signals, and female preference functions may vary depending on mate availability, female reproductive state, and environmental conditions. In Photinus fireflies (Coleoptera: Lampyridae), flying males emit bioluminescent flash signals to locate sedentary females, which reply selectively to attractive male flash signals with their own response flash. In this study, we first examined temporal variation in the paired-pulse flash patterns produced by Photinus greeni males in the field and found significant among-male variation ([~]70% of total variation) in interpulse intervals (IPIs). There was no significant relationship between male IPI and spermatophore size, suggesting that P. greeni male courtship signals do not provide females with reliable indicators of male material resources. In laboratory playback experiments, we presented P. greeni females with simulated flash signals to assess how IPI and pulse duration independently affected the likelihood of female flash response. We also examined the effects of female body mass and time during the mating season on female preference functions, hypothesizing that females would be less discriminating when they were heavier (more fecund) and when mate availability declined. We found that P. greeni females discriminated among signals within their species' range based primarily on flash pattern IPI. Neither the time during the mating season nor female weight altered female preference functions for IPI, although season did influence female response to pulse duration. These results reveal that P. greeni females discriminate among conspecific males based primarily on male IPIs, the same signal character previously shown to be important for firefly species recognition. Field playback experiments indicated that female responsiveness peaked near the average IPI given by males at different ambient temperatures, suggesting that fireflies exhibit temperature coupling similar to that seen in many acoustically signaling animals.
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Sperm storage and viability in Photinus fireflies
Journal of Insect Physiology, 2005Co-Authors: Kristian C. DemaryAbstract:In many species females mate with and store sperm from multiple males, and some female insects have evolved multiple compartments for sperm storage. Sperm storage and sperm viability were investigated in two firefly species, Photinus greeni and P. ignitus, which differ in the morphology of the female reproductive tract. Although the primary spermatheca is similar in both species, P. greeni females have an additional, conspicuous outpocketing within the bursa copulatrix whose potential role in sperm storage was investigated in this study. An assay that distinguishes between live and dead sperm was used to examine sperm viability in male seminal vesicles and sperm storage sites within the female reproductive tract. For both Photinus species, sperm from male seminal vesicles showed significantly higher viability compared to sperm from the primary spermatheca of single mated females. In single mated P. greeni females, sperm taken from the channel outpocketing (secondary spermatheca) showed significantly higher viability compared to sperm from the primary spermatheca. This sperm viability difference was not evident in double mated females. There were no significant differences between P. greeni and P. ignitus females in the viability of sperm from the primary spermatheca. These studies contribute to our understanding of post-mating processes that may influence paternity success, and suggest that sexual conflict over control of fertilizations may occur in multiply mated firefly females. © 2005 Elsevier Ltd. All rights reserved.
Anthony K Campbell - One of the best experts on this subject based on the ideXlab platform.
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sequence and biochemical similarities between the luciferases of the glow worm lampyris noctiluca and the firefly Photinus pyralis
Biochemical Journal, 1996Co-Authors: Graciela Salanewby, Catherine M Thomson, Anthony K CampbellAbstract:A full-length clone encoding Lampyris noctiluca (British glow-worm) luciferase was isolated from a complementary DNA (cDNA) expression library constructed with mRNA extracted from light organs. The luciferase was a 547-residue protein, as deduced from the nucleotide sequence. The protein was closely related to those of other lampyrid beetles, the similarity to Photinus pyralis luciferase being 84% and to Luciola 67%. In contrast, Lampyris luciferase had less sequence similarity to the luciferases of the click beetle Pyrophorus, at 48%. Engineering Lampyris luciferase in vitro showed that the C-terminal peptide containing 12 amino acids in Photinus and 9 amino acids in Lampyris was essential for bioluminescence. The pH optimum and the Km values for ATP and luciferin were similar for both Photinus and Lampyris luciferases, although the light emitted by the latter shifted towards the blue and was less stable at 37 °C. It was concluded that the molecular and biochemical properties were not sufficient to explain the glowing or flashing of the two beetles Lampyris and Photinus.
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Sequence and biochemical similarities between the luciferases of the glow-worm Lampyris noctiluca and the firefly Photinus pyralis.
The Biochemical journal, 1996Co-Authors: G B Sala-newby, Catherine M Thomson, Anthony K CampbellAbstract:A full-length clone encoding Lampyris noctiluca (British glow-worm) luciferase was isolated from a complementary DNA (cDNA) expression library constructed with MRNA extracted from light organs. The luciferase was a 547-residue protein, as deduced from the nucleotide sequence. The protein was closely related to those of other lampyrid beetles, the similarity to Photinus pyralis luciferase being 84% and to Luciola 67%. In contrast, Lampyris luciferase had less sequence similarity to the luciferases of the click beetle Pyrophorus, at 48%. Engineering Lampyris luciferase in vitro showed that the C-terminal peptide containing 12 amino acids in Photinus and 9 amino acids in Lampyris was essential for bioluminescence. The pH optimum and the Km values for ATP and luciferin were similar for both Photinus and Lampyris luciferases, although the light emitted by the latter shifted towards the blue and was less stable at 37 degrees C. It was concluded that the molecular and biochemical properties were not sufficient to explain the glowing or flashing of the two beetles Lampyris and Photinus.
Joaquim Esteves C G Da Silva - One of the best experts on this subject based on the ideXlab platform.
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td dft molecular mechanics study of the Photinus pyralis bioluminescence system
Journal of Physical Chemistry B, 2012Co-Authors: Luis Pinto Da Silva, Joaquim Esteves C G Da SilvaAbstract:This is the first report of a computational study of the bioluminescence of ligand-bound Photinus pyralis luciferase. A time-dependent PBE0/molecular mechanics approach was used to study the interaction between excited-state oxyluciferin (Keto-(−1)) and neighboring active site molecules. The results of these calculations demonstrated that the most important intermolecular interactions are: blue-shifting ionic interactions, red-shifting π–π stacking, and red/blue shifting hydrogen bonding. Subsequent molecular dynamics simulations further supported these conclusions.
Kristian Demary - One of the best experts on this subject based on the ideXlab platform.
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firefly courtship behavioral and morphological predictors of male mating success in Photinus greeni
Ethology, 2006Co-Authors: Kristian Demary, Constantinos I. Michaelidis, Sara M. LewisAbstract:Differences in male mating success can generate selection on male morphological traits and courtship behaviors involved in male–male competition or female mate choice. In Photinus fireflies (Coleoptera: Lampyridae), courtship is based on bioluminescent flash signals produced by both sexes. We conducted field observations of Photinus greeni fireflies engaged in competitive courtships, in which females are able to simultaneously assess several males, to identify male morphological traits and courtship behaviors that might predict male mating success. Male morphological traits did not differ between males that successfully mated compared with unsuccessful males (dialoging males that did not mate). However, courtship behavioral interactions differed: successful males tended to have higher flash pattern rates (number of flash patterns per minute), and their courtship flashes were more likely to be answered by females. We also examined how the risk of predation by Photuris fireflies altered courtship behavior of their Photinus prey. When predatory Photuris fireflies were present, P. greeni females were less likely to mate, and showed decreased flash responses to most males. However, P. greeni males that did successfully mate in spite of Photuris presence were males that maintained high flash pattern rates that elicited female responses. These results suggest that both female mate choice and Photuris predation exert strong selective pressures on the evolution of courtship signals in Photinus fireflies.
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sperm storage and viability in Photinus fireflies
Journal of Insect Physiology, 2005Co-Authors: Kristian DemaryAbstract:In many species females mate with and store sperm from multiple males, and some female insects have evolved multiple compartments for sperm storage. Sperm storage and sperm viability were investigated in two firefly species, Photinus greeni and P. ignitus, which differ in the morphology of the female reproductive tract. Although the primary spermatheca is similar in both species, P. greeni females have an additional, conspicuous outpocketing within the bursa copulatrix whose potential role in sperm storage was investigated in this study. An assay that distinguishes between live and dead sperm was used to examine sperm viability in male seminal vesicles and sperm storage sites within the female reproductive tract. For both Photinus species, sperm from male seminal vesicles showed significantly higher viability compared to sperm from the primary spermatheca of single mated females. In single mated P. greeni females, sperm taken from the channel outpocketing (secondary spermatheca) showed significantly higher viability compared to sperm from the primary spermatheca. This sperm viability difference was not evident in double mated females. There were no significant differences between P. greeni and P. ignitus females in the viability of sperm from the primary spermatheca. These studies contribute to our understanding of post-mating processes that may influence paternity success, and suggest that sexual conflict over control of fertilizations may occur in multiply mated firefly females.
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Mate recognition and choice in Photinus fireflies
Fennici — Ann. Zool. Fennici, 2004Co-Authors: Sara M. Lewis, Christopher K Cratsley, Kristian DemaryAbstract:This paper offers a view of firefly mate recognition and choice seen through the lens of recognition system theory. We review the expression and perception of firefly bio-luminescent signals, and describe the photic cues used by Photinus fireflies (Coleop-tera: Lampyridae) in the processes of species recognition (identifying conspecifics) and mate-quality recognition (discriminating among potential conspecific mates). The signal characters used by Photinus females to discriminate among potential mates include flash pulse rate and pulse duration, similar temporal characters to those assessed by females in acoustically signaling insects. We also review male nuptial gift production and transfer, and describe the relationship found between male flash sig-nals and nuptial gift size for Photinus ignitus. We present evidence of mate choice by Photinus males, which appear to allocate limited resources by rejecting low fecundity females. We assess the potential for postcopulatory female choice to mediate mate acceptance errors by increasing paternity success of higher quality mates, or blocking fertilizations by low quality mates. Finally, we integrate recognition system and mate choice theoretical approaches to develop predictions concerning how various factors will alter both male and female mate acceptance thresholds for Photinus fireflies.
