Effect of water-soluble fraction of Cook Inlet crude oil on swimming performance and plasma cortisol in juvenile coho salmon (Oncorhynchus kisutch)

Swimming performance of juvenile coho salmon decreased and plasma cortisol increased, following 48-hr exposure to the water-soluble fraction (WSF) of Cook Inlet crude oil at 75% of the LC50. Exposure to 25 and 50% of the LC50 did not significantly reduce swimming performance. Plasma cortisol concentrations were highest in fish exposed to both the combined stress of WSF exposure and of forced swimming in a stamina tunnel.     

Circadian Reproductive Rhythms, Pair-Bonding, and Evidence for Sex-Specific Pheromones in Nadezhdiella cantori (Coleoptera: Cerambycidae)

Mating and oviposition rhythms and evidence for sex-specific pheromones of the gray-black citrus longicorn beetle Nadezhdiella cantori were investigated. The reproductive and flight activities of this insect mainly occurred between 1700 and 2400 h, and each activity had two peaks with the first one taking place within the 3 h before sunset (2100 h) and the second occurring within the 3 h after sunset. Circadian rhythms of mating and oviposition were significantly correlated but neither mating nor oviposition was significantly correlated with flight. It is suggested that mating and oviposition repeat in turn during pair-bonding and that flight is an indication of termination of reproductive activities in some individuals of a population. Males differentiated between sexes by touching. Mating behavior of males was stimulated by a contact female sex pheromone on the female body surface. Fighting behavior of males was mediated by a chemical on the male body surface. Females left trails of the contact sex pheromone on the trees when walking, which males used to locate them. Implications of these findings are discussed.     

Reproductive compatibility among latitudinally separated Scottolana canadensis (Willey) (Harpacticoida)

Scottolana canadensis is distributed widely along the east coast of North America. Although males exhibited mating behavior with females copepodites, copulation occurred following the female terminal molt. Crossing experiments revealed that in some cases, male mating behavior decreased with increasing latitudinal distance of male and female source locales. However, latitudinally-related differences in copepod body size most likely did not contribute to variation in male mating behavior. Survival patterns of fertilized eggs and fertility of offspring revealed postzygotic reproductive isolation of Florida populations from all others collected north to Maine.     

Disruption of male spruce budworm orientation to female moths by pheromone and pheromone analogues in a wind tunnel

Abstract. The ability of male spruce budworm moths, Choristoneura fumiferana (Clem.), to orientate to and locate virgin female moths was investigated in a laboratory wind tunnel. When presented with two caged ‘target female’ moths, more than 99% of the male moths locked on and flew directly to the females. When confined for 3 h before release, downwind of a three-dimensional array of thirty-five evenly distributed female moths (a density of 40/m³), over 90% of the males still successfully oriented to one or another of the females, although not always to the target females. With an array of thirty-five septa containing either E-11-tetradecenyl acetate on E-11-tetradecenol there was no visible change in behaviour; >90% of the males flew directly to the two target females, which indicates that neither the acetate nor the alcohol has potential for mating disruption. An array of thirty-five septa containing a 955 blend of E- and Z-11-tetradecenal, the main components of the spruce budworm sex pheromone, significantly reduced the numbers of male moths able to locate the target females, and effects were concentration-dependent. The highest concentration, which gave a release rate similar to that of a calling female, produced the same level of disruption as the thirty-five females, but sensory fatigue became a factor in addition to ‘false trail following’. Lower concentrations were significantly less effective, with no evidence of sensory fatigue. At all concentrations significant numbers of males flew to the septa (false trail following), but when male moths were left uncaged in the tunnel for a further 3h, most eventually located the females. This suggests that false trail following alone will not prevent mating. The level of disruption was not improved by the addition of 2% tetradecanal to the 955 blend. Similar levels of disruption to the 955 blend were obtained with an 80:20 blend. A 5050 blend still caused a significant amount of false trail following, but less than the other blends. The ability of male spruce budworm to orientate to off-blend trails was enhanced if the males were first exposed to the natural, female-produced pheromone.     

Dispersal of Udonella australis (Monogenea: Udonellidae) between caligid copepods Caligus rogercresseyi and Lepeophtheirus mugiloidis on Chilean rock cod

Udonella australis is a platyhelminth that lives on the surface of the ectoparasite copepods Caligus rogercresseyi and Lepeophtheirus mugiloidis, which coexist on the Chilean rock cod Eleginops maclovinus. The absence of a planktonic oncomiracidium stage in the life cycle of udonellids may limit their dispersal ability. However, the high prevalence and intensity of U. australis on C. rogercresseyi suggest they have developed dispersal strategies to compensate for the lack of a free-living larval stage. The goals of this study were to determine the main dispersal mechanisms of U. australis in 1 copepod species and to compare the dispersal ability of U. australis between 2 different copepod species. Chilean rock cods were infected with female (without udonellids) and male (with and without udonellids) C. rogercresseyi. Other fishes were also infected with this copepod (with U. australis) and with L. mugiloidis (without U. australis). The dispersal of udonellids among copepods occurs through both intraspecific and interspecific processes. The main dispersal mechanism appears to be copepod mating; contact between same-sex individuals is less important. Intraspecific dispersal seems to be more dependent on the number of udonellids per fish than on copepod abundance, as observed for interspecific dispersal.     

Hang on or run? Copepod mating versus predation risk in contrasting environments

Mating durations of copepods were found to differ significantly between fishless high-altitude waters and lowland lakes containing fish. In lowland species the whole mating process was completed within a few minutes, but it averaged over an hour in high-altitude species. Alpine copepods showed a prolonged post-copulatory association between mates, during which the male clasped the female for an extended period after spermatophore transfer, while in lowland species males abandoned their partner immediately after copulation. Prolonged associations also occurred after transfer of spermatophores to heterospecific females with shorter conspecific mating duration, suggesting that male interests largely dictate the time spent in tandem. The differences observed may be adaptations to environments with different predation pressure, as pairs in tandem are more conspicuous and less reactive than single animals. We argue that differences in mating behavior and mating duration evolved under sexual versus natural selection, reflecting trade-offs between enhancement of fertilization success and reduction of vulnerability to visual predation. In fishless mountain lakes with high intrasexual competition, guarding males can reduce the risk of spermatophore displacement or the risk that the female will accept sperm from rival males without increased risk of being eaten, thereby maximizing paternity. Populations from fishless alpine lakes further differed from lowland species by exhibiting higher female/male size dimorphism and more intense pigmentation. While these traits vary between populations according to predation pressure, mating duration appears to be more species-specific.     

Tracking of Female Conspecific Odor Trails by Male Broad-headed Skinks (Eumeces laticeps)

The ability of the broad-headed skink (Eumeces laticeps) to follow conspecific odor trails on paper substrates was investigated in y-maze experiments. Adult males enter the trail-containing arm at much greater than chance frequency when the odor source is female. The data support the hypothesis that males can follow odor trails of females. The often-repeated direct contact with the trail made by tongue-flicking as the lizard passed through the maze provided evidence that males could follow the scent. There was no evidence that males followed male odors or that females followed trails laid by either sex. It is suggested that the major selective force leading to evolution by males of the ability to trail females was an increase in reproductive success accruing to males able to locate females and guard them during a temporally limited period of sexual receptivity.     

Possible Presence of Pheromone in Mating Behavior of the Pine Sawyer Monochamus saltuarius Gebler (Coleoptera: Cerambycidae)

The mating behavior of the pine sawyer, Monochamus saltuarius, is composed of two phases. The first phase is the female approach to pheromone-releasing males. When bioassayed by T-tube olfactometer, the female was moved toward the male and hexane extract of the male. The second phase is the male mounted the female to copulate after perceiving the contact pheromone being on the female body surface. When the hexane extract of the female body surface was applied onto a glass rod (dummy), the male showed the mating behavior to the dummy. The component of female body surface extract fractionated using a silicic acid column elicited mating behaviors of the males, and the other component by ether fraction was showed a high copulatory attempt. This study was discussed two-step functions of the pheromones in the beetle mating behavior.     

Modeling mate-finding behavior of the swarming polychaete,Nereis succinea,with TangoInSilico,a scientific orkflow-based simulation system for sexual searching

Summary

Pheromones can be used as attractants for the opposite sex in many environments; however, little is known about the search strategies employed in responding to pheromones in the marine environment. The spawning behavior of males of the polychaete Nereis succinea is known to be triggered at close range by a high concentration (>～10^?7 M) of pheromone, cysteine glutathione disulfide (CSSG), released by females. Since CSSG also causes acceleration of swimming and increased turning, in addition to eliciting ejaculation, we proposed the hypothesis that these behaviors elicited by low concentrations of pheromone can be used by males to find females. The current study develops a computer simulation model of male and female N. succinea behavior for testing whether male responses to low concentrations of CSSG can facilitate finding females. Video recording of female swimming behavior in the field showed spontaneous loops, spirals, and circles that have been incorporated into the model. The scientific workflow paradigm within which the computer model has been developed also incorporates a data provenance system to enable systematic replay and testing of responses to individual parameters. Output of the model shows complex turning behavior leading to successful mating encounters at concentrations as low as 3×10^?9 M CSSG. Behavior resembling the output of the model was recorded in field observations. Application of the model in the future will be used to determine what pheromone concentrations produce significant increases in the probability of mating encounters.     

Sexual communication in copepods and rotifers

The problem of locating mates and identifying them as conspecifics is similar for Copepoda, Cladocera, and Rotifera since they are all relatively small animals moving in a large volume of water. Chemoreception is a potentially effective means of identifying mates in aquatic environments. In zooplankton, mate recognition systems based on chemoreception have evolved which can distinguish conspecifics from other species and can discriminate males from females. The evidence for the role of chemical signals in copepod mating is indirect, based on observations of mating behavior. The small size and limited metabolic capability of zooplankton, and high diffusion rates at 1–10 mm spatial scales, restrict the volume through which chemical signals can be effectively transmitted. An alternative to using diffusible molecules for sexual communication is to bind signal molecules to cell surfaces, allowing energetically costly molecules like proteins to serve as signals without their loss through diffusion. Contact chemoreception has been described in copepod and rotifer mating and perhaps represents a general solution to the problem of chemical communication by small zooplankters. The types of signals used, their mechanisms of transmission and reception, and their role in maintaining reproductive isolation among species has yet to be characterized for any aquatic invertebrate. In this review, I compare the methods used by copepods and rotifers for mate seeking and recognition, describe the behavioral evidence supporting the existence of chemical cues, and examine experiments describing the biochemical characteristics of the signal molecules. In copepods, male mate seeking behavior occurs without previous female contact, suggesting the reception of a diffusible signal. The signal molecule is small and lacks species specificity in the species investigated. Male rotifers do not respond to females from a distance. Mates are located by random male swimming and contact chemoreception of a species-specific signal. Mate recognition in both copepods and rotifers is based on contact chemoreception of a species-specific signal. The pheromones responsible are not known for copepods, but surface glycoproteins with pheromonal activity have been identified in rotifers. The structure of the rotifer sex pheromone has been probed by selective enzymatic degradation and lectin binding, electrophoretic characterization, and attachment to agarose beads to assess its biological activity. Glycoproteins play a key role in the sexual communication of some algal and ciliate species and have well characterized roles in cellular recognition phenomena like sperm-egg binding. The significance of these studies lies in their contribution to our understanding of zooplankton reproductive biology, the chemical ecology of male-female communication, the molecular basis of chemoreception in the aquatic environment, and the evolution of pre-mating reproductive isolating mechanisms in zooplankton.     

Mating behavior in eight rotifer species: using cross-mating tests to study species boundaries

We characterized the mating behavior of eight freshwater rotifer species from five different families of Monogononts (Asplanchnidae, Brachionidae, Euchlanidae, Lecanidae, and Trichocercidae). Were corded the percentages of male-female encounters resulting in mating attempts and the number of completed copulations. The characterization of mating behavior also included data on: (1) duration of copulation, (2) female and male swimming speed, (3) sites of initial mating attempts, (4) sites of copulation, and (5) sizes of males and females. In the five families investigated, cross-mating tests may be used to assess the ability of males to discriminate conspecifics, establishing limits to gene flow. We also present data on two families, Brachionidae and Lecanidae where we used cross-mating tests to compare discrimination between conspecific females and those of other species. Brachionus calyciflorus males attempted mating with females of the closely related genus Plationus, but did not attempt mating with Keratella Americana females. Males of other three Brachionidae species only attempted mating with nonspecific females. Lecane quadridentata males attempted to mate with females of two different Lecane species besides their own. Percentages of mating attempts and completed copulations were quantified in all crosses. Lower percentages of copulation after a mating attempt were found among brachionids than among non-brachionids. These data demonstrate that male discrimination of females is an effective pre-mating reproductive barrier in several species of Monogonont rotifers. These results, further suggest that investigations of mating behavior are useful for determining species boundaries in rotifers and perhaps other zooplankters. This revised version was published online in August 2006 with corrections to the Cover Date.     

Reproductive strategies in snakes

Snakes of both sexes display remarkable flexibility and diversity in their reproductive tactics. Many features of reproduction in female snakes (such as reproductive mode and frequency, seasonality and multiple mating) allow flexible maternal control. For example, females can manipulate not only the genotypes of their offspring (through mate choice or enhanced sperm competition) but also the phenotypes of their offspring (through allocation 'decisions', behavioural and physiological thermoregulation, and nest-site selection). Reliance on stored energy ('capital') to fuel breeding results in low frequencies of female reproduction and, in extreme cases, semelparity. A sophisticated vomeronasal system not only allows male snakes to locate reproductive females by following scent trails, but also facilitates pheromonally mediated mate choice by males. Male-male rivalry takes diverse forms, including female mimicry and mate guarding; combat bouts impose strong selection for large body size in males of some species. Intraspecific (geographical) variation and phenotypic plasticity in a wide array of reproductive traits (offspring size and number; reproductive frequency; incidence of multiple mating; male tactics such as mate guarding and combat; mate choice criteria) provide exceptional opportunities for future studies.     

Female mating status does not affect male mating behavior in the West Indian sweetpotato weevil, Euscepes postfasciatus

Because multiple mating by females encourages sperm competition, the assessment of female mating status before insemination is important for males in order to avoid the risk of sperm competition or to intensify sperm competition. When interacting with females before sperm transfer, males can alter their mating tactics according to the risk or intensity of sperm competition. Information on how mating systems are associated with sperm competition is essential for sterile insect technique eradication programs, which depend on successful mating of released sterile males with wild females. We tested whether males of the West Indian sweetpotato weevil, Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae), adjusted their mating behavior in response to female mating experience and/or age. As virgin/young female weevils accepted males more easily than non-virgin/old females, assessing females before insemination can be adaptive for male weevils. We found that E. postfasciatus males were unable to adjust their mating tactics in response to female mating status. Although this mating strategy would be costly for individual male weevils, the ability in males to discriminate female mating status can prevent the chance of mating with already-mated females containing the sperm of wild male(s). Therefore, the mating tactics of male E. postfasciatus are advantageous for sterile insect technique eradication programs.     

The turn of the sword: length increases male swimming costs in swordtails

Sexual selection via female mate choice can result in the evolution of elaborate male traits that incur substantial costs for males. Despite increased interest in how female mating preferences contribute to the evolution of male traits, few studies have directly quantified the locomotor costs of such traits. A sexually selected trait that could affect movement costs is the sword exhibited by male swordtail fishes: while longer swords may increase male mating success, they could negatively affect the hydrodynamic aspects of swimming activities. Here, we examine the energetic costs of the sword in Xiphophorus montezumae by experimentally manipulating sword length and measuring male aerobic metabolism during two types of activity, routine swimming and courtship swimming. Direct measurements of oxygen consumption indicate that males with longer swords expend more energy than males with shortened swords during both types of swimming. In addition, the sword increases the cost of male courtship. Thus, while sexual selection via female choice favours long swords, males with longer swords experience higher metabolic costs during swimming, suggesting that sexual and natural selection have opposing effects on sword evolution. This study demonstrates a hydrodynamic cost of a sexually selected trait. In addition, this study discriminates between the cost of a sexually selected trait used in courtship and other courtship costs.     

First evidences of sexual selection by mate choice in marine zooplankton

Sexual selection is potentially important in marine zooplankton, presumably the most abundant metazoans on earth, but it has never been documented. We examine the conditions for sexual selection through mate choice and describe mating preferences in relation to size in a marine zooplankter, the pelagic copepod Acartia tonsa. Males produce spermatophores at a rate (~1 day⁻¹) much lower than known female encounter rates for most of the year and the decision to mate a particular female thus implies lost future opportunities. Female egg production increases with female size, and males mating larger females therefore sire more offspring per mating event. Similarly, females encounter males more frequently than they need to mate. Large males produce larger spermatophores than small males and the offspring production of female increases with the size of the spermatophore she receives. Additionally, large spermatophores allow females to fertilize eggs for a longer period. Thus, mating with large males reduces the female’s need for frequent matings and she may sire sons that produce more offspring because size is heritable in copepods. Finally, we show that both males and females mate preferentially with large partners. This is the first demonstration of sexual selection by mate choice in a planktonic organism.     

Chemical Composition and Potential Environmental Impacts of Water-Soluble Polar Crude Oil Components Inferred from ESI FT-ICR MS

Polar petroleum components enter marine environments through oil spills and natural seepages each year. Lately, they are receiving increased attention due to their potential toxicity to marine organisms and persistence in the environment. We conducted a laboratory experiment and employed state-of-the-art Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) to characterize the polar petroleum components within two operationally-defined seawater fractions: the water-soluble fraction (WSF), which includes only water-soluble molecules, and the water-accommodated fraction (WAF), which includes WSF and microscopic oil droplets. Our results show that compounds with higher heteroatom (N, S, O) to carbon ratios (NSO:C) than the parent oil were selectively partitioned into seawater in both fractions, reflecting the influence of polarity on aqueous solubility. WAF and WSF were compositionally distinct, with unique distributions of compounds across a range of hydrophobicity. These compositional differences will likely result in disparate impacts on environmental health and organismal toxicity, and thus highlight the need to distinguish between these often-interchangeable terminologies in toxicology studies. We use an empirical model to estimate hydrophobicity character for individual molecules within these complex mixtures and provide an estimate of the potential environmental impacts of different crude oil components.     

Hindsight by genitalia: photo-guided copulation in butterflies

1. Butterflies have two pairs of extraocular photoreceptive neurons on the genitalia. Here we report that the genital photoreceptors have a crucial role in achieving copulation. 2. We first investigated mating behavior of the butterfly Papilio xuthus in an outdoor cage. The mating behavior consists of six steps: the male approaches the female (1), maneuvers into a ventor-to-ventor position with the female (2), searches the female's genitalia (3), clasps the genitalia (4), the pair copulates (5), and finally separates (6). 3. We bilaterally ablated the P1 pair of photoreceptors, in the males, and observed mating behavior with virgin females. Of the intact males 66% copulated successfully, whereas only about 25% of the treated males could copulate. About 40% of P1 ablated males stopped the mating behavior during step 3: the males could not locate the female's genitalia. P1 ablation in females did not have a clear effect in this study. 4. Electrophysiological measurements showed that the P1 response of a male drops sharply when it correctly locates the female's genitalia. We hypothesize that the sharp drop in the P1 response informs the male that the female's vagina is correctly positioned for penis insertion. The P1 ablated males never experience such␣a␣response drop, as there is no P1 response to begin with. Accepted: 18 October 1996     

Mating Status Effects on Sexual Response of Males and Females in the Parasitoid Wasp <Emphasis Type="Italic">Urolepis rufipes</Emphasis>

Although mate preferences are most commonly examined in females, they are often found in both sexes. In the parasitoid wasp Urolepis rufipes, both female and male mating status affected certain aspects of sexual interactions. Female mating status mattered only in the later stages of mating. Males did not discriminate between virgin and mated females in terms of which they contacted or mounted first. However, once mounted, most virgin females were receptive to copulation, whereas very few mated females were. Whether a male’s mating status affected his own sexual response depended on the female’s ability to respond and the stage of mating. Examining male behavior toward dead females allowed elimination of the role of female behavior in how males responded. Virgin and mated males are both attracted to dead females as evidenced by their fanning their wings at such females. However, mated males were quicker than virgin males to contact and to mount in an experiment with dead females, whereas there was no such differential response in an experiment with live females. This difference is consistent with greater female sexual responsiveness to virgin males. Male mating status also affected female receptivity to copulate. Once mounted, live virgin females were less likely to become receptive to copulation by mated males than to virgin males, but only in a choice experiment, not in a no-choice experiment.     

Mate choice and sexual conflict in <Emphasis Type="Italic">Brachionus plicatilis</Emphasis> (Rotifera)

Male mate choice in Brachionus plicatilis is based on information from coronal receptors and contact chemoreception of a glycoprotein signal on the body surface of females. Male mating behavior is modulated by mating signal quality and strength, which determines male mating persistence and circling intensity. We probe the sensory abilities of males by better resolving their discrimination of female age. Males preferentially initiate mating with young females, but not too young. Males circle 0.2 h old females just hatched from resting eggs only about 1/2 as frequently as 12 h old females. Males are even more discriminating of females with whom they copulate, preferring 3 h old females significantly more than 0.2 h or 6 h old females. In contrast, males cannot distinguish between virgin females and those who have already copulated. Similarly, males circled and copulated with females hatching from resting eggs with equal frequency as those hatching from amictic eggs. The counterpoint to male mate choice is female resistance to mating. When males contact females, the females respond with one of four behaviors: no response, acceleration, foot flipping, or coronal retraction. In 65% of male–female encounters, there was no initial response by females. However, when males began circling females, females accelerated 11.1 times more often than when males were absent. The second type of evasive female behavior was foot-flipping, which tends to knock off males attempting to circle the female. In the presence of circling males, females performed foot-flipping behavior three times more often than in the absence of males. Coronal retraction, where they stop swimming and withdraw their corona, was observed less frequently than acceleration or foot-flipping, and there was no difference in the presence or absence of males. These data are interpreted in the context of sexual conflict, where the behaviors that optimize male and female fitness differ. Guest editors: S. S. S. Sarma, R. D. Gulati, R. L. Wallace, S. Nandini, H. J. Dumont & R. Rico-Martínez Advances in Rotifer Research     

Mating behavior and male mating success in wildAnastrepha Ludens (Diptera: Tephritidae) on a field-caged host tree

Mating behavior and factors affecting mating success of males were studied using wild Anastrepha ludens on a fieldcaged host tree. The most common courtship sequence had five components: (1) male calls from the underside of a leaf, (2) female arrives to the maleoccupied leaf, (3) male orients to female and stops calling, (4) one or both approach to a face-to-face position 1–3 cm apart, and (5) male mounts female after 1–2 s. Courtship behavior was almost identical to that of laboratoryculture flies observed previously under laboratory conditions. Most malefemale encounters occurred at a height of 1–2m, well inside the outer canopy of the tree. Differential mating success by males occurred. No male mated more than once per day, owing possibly to a very short sexual activity period. Factors favoring mating success of males were survival ability and tendency to join male aggregations and to fight other males. Thorax length and age (9–11 days difference) had no effects on male copulatory success. Overall win/loss percentage was not related to mating success because the males that were most successful at mating fought mostly among themselves, driving their win/loss percentage down. However, these successful males (at mating) won most of their fights against less successful males. Results confirmed a lek mating system: males aggregated, called, and defended territories; territories did not contain femalerequired resources; and females exercised mate choice, apparently through selection of sites within leks.