Flash behavior of femalePhoturis versicolor fireflies (Coleoptera: Lampyridae) in simulated courtship and predatory dialogues

FemalePhoturis versicolor fireflies attempt to capture males by responding to heterospecific flash patterns. A mating-dependent switch occurs which affects response timing and frequency of female flashes. We examined the switch using females of known age, mating status, and flash experience to assess how accurate mimicry is, what factors influence it, and what mechanism produces it. Presentations of simulated male flash patterns before and after mating revealed elements of an entrainment mechanism controlling female responsiveness. Unmated females preferentially answered conspecific patterns with variable latencies, averaging 1 s. Mating induced changes in both response frequency and response latency: Females answered heterospecific patterns more frequently, and latencies elicited by conspecific patterns shifted away from the unmated range. Heterogeneity in mean and variance of response latency among individuals indicates that females do not share a discrete reply to a given pattern. Little correspondence exists between latencies of sympatric species andP. versicolor females, suggesting that the flash response mechanism produces entriainment to any rhythmic pattern, not a one-to-one matching between prey and predator latencies. Different selective scenarios underlie strict mimicry versus entrainment mimicry.     

Is the firefly flash regulated by calcium?

The very different courtship flashes of Photuris versicolorand Photuris lucicrescens males mirror the pattern of neuralimpulses produced by their brain. Their lanterns luminescencevery differently, however, in response to direct, electricalstimulation. Whereas P. lucicrescens lanterns glow in responseto high frequency, continuous electrical stimulation, thoseof P. versicolor produce only rapid, triple-pulsed flashlettesthat resemble, but are not identical to, their courtship flashes.In addition, the exposed lantern tissue of P. versicolor males,when immersed in firefly saline high in potassium and calciumions, scintillates with hundreds of photocytes flashing in randomfashion. P. lucicrescens male lanterns, so treated, only glow.Tests of P. versicolor lanterns with salines of different compositionsuggest that calcium ions are essential in producing this intense,long lasting scintillation response and are therefore possiblyimplicated in the final stages of flash control in this species.     

Advertisement-call preferences in diploid-tetraploid treefrogs (Hyla chrysoscelis and Hyla versicolor): implications for mate choice and the evolution of communication systems

Signals used for mate choice and receiver preferences are often assumed to coevolve in a lock-step fashion. However, sender-receiver coevolution can also be nonparallel: even if species differences in signals are mainly quantitative, females of some closely related species have qualitatively different preferences and underlying mechanisms. Two-alternative playback experiments using synthetic calls that differed in fine-scale temporal properties identified the receiver criteria in females of the treefrog Hyla chrysoscelis for comparison with female criteria in a cryptic tetraploid species (H. versicolor); detailed preference functions were also generated for both species based on natural patterns of variation in temporal properties. The species were similar in three respects: (1) pulses of constant frequency were as attractive as the frequency-modulated pulses typical of conspecific calls; (2) changes in preferences with temperature paralleled temperature-dependent changes in male calls; and (3) preference functions were unimodal, with weakly defined peaks estimated at values slightly higher than the estimated means in conspecific calls. There were also species differences: (1) preference function slopes were steeper in H. chrysoscelis than in H. versicolor; (2) preferences were more intensity independent in H. chrysoscelis than in H. versicolor; (3) a synergistic effect of differences in pulse rate and shape on preference strength occurred in H. versicolor but not in H. chrysoscelis; and (4) a preference for the pulse shape typical of conspecific calls was expressed at the species-typical pulse duration in H. versicolor but not in H. chrysoscelis. However, females of H. chrysoscelis did express a preference based on pulse shape when tested with longer-than-average pulses, suggesting a hypothesis that could account for some examples of nonparallel coevolution. Namely, preferences can be hidden or revealed depending on the direction of quantitative change in a signal property relative to the threshold for resolving differences in that property. The results of the experiments reported here also predict patterns of mate choice within and between contemporary populations. First, intraspecific mate choice in both species is expected to be strongly influenced by variation in temperature among calling males. Second, simultaneous differences in pulse rate and pulse shape are required for effective species discrimination by females of H. versicolor but not by females of H. chrysoscelis. Third, there is greater potential for sexual selection within populations and for discrimination against calls produced by males in other geographically remote populations in H. chrysoscelis than in H. versicolor.     

Firefly Courtship: Behavioral and Morphological Predictors of Male Mating Success in Photinus greeni

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.     

Diel vertical migrations of invertebrate predators (Leptodora kindtii ,Thermocyclops taihokuensis, andMesocyclops sp .) in a shallow, eutrophic lake

We studied vertical distribution patterns of three invertebrate predators – Leptodora kindtii, Mesocyclopssp., and Thermocyclops taihokuensis– in a shallow eutrophic lake, Lake Suwa , Japan. From June to October in 2000 and 2001, we collected samples in the lake center in order to examine the vertical distribution patterns and the densities of the predators in the water column during the day (0900) and at night (2330). We also examined phototactic behavior of Leptodora in the laboratory. The three invertebrate predators showed clear migration patterns. Leptodora and Thermocyclops displayed a typical migration, avoiding the surface and maintaining a high abundance in deeper water during the day, and being distributed uniformly during the night. Mesocyclops, on the other hand, showed no clear vertical distribution pattern in the water column. However, Mesocyclops showed higher densities in the water column during the night than during the day. It suggests that they stayed just above the bottom during the day and migrated upward during the night. Leptodora also showed such a density difference between day and night. In the laboratory, Leptodora showed strong negative phototactic behavior. The observed density changes between day and night in Leptodora and Mesocyclops suggests the possible underestimation of their population density by usual sampling methods, and thus the impact of predation on populations of prey zooplankton species may also be underestimated in shallow water bodies.     

Heterogeneity in the concerted evolution process of a tandem satellite array in meadow mice (Microtus)

The evolutionary history of a 160-bp tandem satellite array, originally described from Microtus chrotorrhinus and called MSAT-160, was examined in related species of arvicolid rodents by sequence analyses, quantitative dot blotting, and Southern blotting. Results indicate that MSAT-160 is present in 12 of the 20 species and subspecies of Microtus assayed, but not in species belonging to any of the eight other genera examined. DNA from each species containing MSAT-160 was digested with 12 restriction endonucleases and restriction patterns were obtained reflecting the variable extent of homogenization of any given variant in different species. For example, with MboI digestion, M. chrotorrhinus produced a type A ladder pattern where most monomers contain the restriction site, M. ochrogaster generated a type B pattern where most monomers lack the site, and M. agrestis yielded a pattern intermediate between the A and B types. Further, dot blotting revealed copy-number differences between species. These findings indicate that changes in the periodic structure and amount of satellite DNA have occured since these species last shared a common ancestor. In addition, various species-pacific patterns were documented, illustrating that mechanism other than genomewide homogenization, such as stochastic mutation, out-of-register crossing over, deletion, and random amplification also play a role in structuring tandem arrays. Stochastic mutation and homogenization rates in satellite DNA, levels of species diversity, and magnitudes of chromosomal divergence differ significantly in Microtus, Mus, and Ctenomys, the three rodent lineages examined.     

Patterns of plant visitation by nectar-feeding lizards

Geckos in the genus Hoplodactylus visit flowers to feed on nectar. I examined the patterns of flower visitation exhibited by two gecko species (H. maculatus and H. duvauceli) having access to two plant species: pohutukawa (Metrosideros excelsa: Myrtaceae) and flax (Phormium tenax: Agavaceae). Individual geckos were not observed to visit both plant species; individuals visiting flax tended to revisit the same plant. Geckos visiting pohutukawa were larger than those visiting flax and exhibited an early night peak in plant visitation, while lizards on flax displayed a more even pattern of activity throughout the night. On flax, geckos were more likely to be found on plants with a greater number of male flowers. Male flax flowers were of greater diameter than female flowers and produced nectar at higher rates and with greater concentrations of sugars. Experimental manipulation of pohutukawa nectar volumes suggested that the distribution of geckos is influenced by the pattern of nectar availability.     

Leaf production,reproductive patterns,field germination and seedling survival in Chamaedorea bartlingiana,a dioecious understory palm

Summary Chamaedorea bartlingiana is a dioecious palm that grows in the cloud forest understories of the Venezuelan Andes. Age and sexual differences in phenology and reproductive patterns were studied in labelled individuals of all age categories. This species has long-lived leaves and low leaf production, both characteristic of understory plants. Growth rates are lower in juveniles than in adults and in females than in males, as in other palms. Male and female individuals show different reproductive patterns. Male inflorescences are always produced at the same rate and the probability of surviving until anthesis is constant. Females produce reproductive buds at the same rate as males, but these buds have a 35% probability of becoming a ripe infrutescence if the plant has infrutescences already growing, and 70% if it does not. This pattern and the slow growth of inflorescences (1 year for males from bud to flowers, 2 years for females from bud to ripe fruits) cause a pluriannual reproductive pattern at the population level. Field germination does not follow this pattern, but shows one annual peak probably related to environmental conditions.     

Early outflying and late homeflying in the Indian pygmy bat under natural conditions

The outflying and homeflying activity pattern of a colony of the Indian pygmy bat Pipistrellus mimus occupying a tunnel was studied under natural conditions. Before leaving the tunnel for foraging, the bats made circling flights outside to sample the environmental light conditions. The onset and end of activity was related to the times of sunset and sunrise respectively. The onset of flight during evening commenced after sunset from mid-September to mid-April, before sunset during the rest of the year. Onset of activity occurred at higher light intensities compared to light intensities prevailing during the return flight to the roost in the morning. The duration of activity time showed a curvilinear relationship with the duration of the night. The phase relationship between onset and end of activity, and sunset and sunrise, showed marked seasonal variations in the values of Ψ_onset, Ψ_end, and Ψ_midpoint. However, such changes in the phase angle properties did not obey Aschoff's seasonal rule. Based upon the data obtained on the onset and end of activity patterns for five species of bats, including the data from this study, we report that P. mimus is the earliest to set out for foraging in the evening and among the last to return home in the morning. This might be due to dusk and dawn peaks in activity of the prey insects.     

Characterization of genetic diversity ofFrankia strains in nodules ofAlnus nepalensis (D. Don) from the Hengduan Mountains on the basis of PCR-RFLP analysis of thenifD-nifK IGS

Nodule samples from 90A. nepalensis individuals were collected at five sites in the Hengduan Mountains. PCR-RFLP analysis of IGS betweennifD andnifK genes was directly applied to unculturedFrankia strains in the nodules. Sizes of thenifD-nifK IGS amplicons and genetic distance between the RFLP patterns from these samples were noticeably different, indicating significant genetic variation in theFrankia population. There were some nodule samples, which produced more than one PCR fragment, and compound RFLP patterns, indicating thatFrankia strains with different PCR-RFLP patterns coexisted in the same host plant under natural conditions. Among the 29 restriction patterns obtained, 5 patterns were found in more than one population and occurred in the majority of samples, while each of the other 24 patterns were represented by only one or two samples and were endemic to a particular population. From the calculatedGst and UPGMA cluster analysis, genetic diversity ofFrankia strains was inferred to be related to climate and glaciation history in the Hengduan Mountains.     

Efficient and Regular Patterns of Nighttime Sleep are Related to Increased Vulnerability to Microsleeps Following a Single Night of Sleep Restriction

Sleep-deprived people, or those performing extended monotonous tasks, can exhibit brief episodes in which they suspend performance and appear to fall asleep momentarily—behavioral microsleeps (“microsleeps”). In this study, microsleeps were identified using eye video and tracking response during a 20-min continuous tracking task undertaken by 16 healthy volunteers (mean age 24.9?yrs; 8 females, 8 males) in the early afternoon following a normally rested night and a night of restricted sleep (time-in-bed restricted to 4?h). Sessions were 1 wk apart and counterbalanced. Wrist actigraphy, self-reported sleepiness, and sleep quality were also recorded. We hypothesized that high microsleep rates when normally rested or after a night of sleep restriction would be related to poor sleep quality, sleep disturbance, circadian type, irregular sleep patterns, low daily sleep duration, or poor sleep efficiency. We also hypothesized that prior performance on a 10-min psychomotor vigilance task (PVT) (mean reaction time or number of PVT lapses) would be related to the number of microsleeps during the tracking task and that PVT performance could, therefore, be used as a fitness-for-duty indicator. The number of microsleeps during the tracking task increased following sleep restriction (mean 11.4 versus 27.9; p?=?0.03). There were no correlations between the number of microsleeps in the normally rested session and any of the actigraphically measured or self-reported sleep measures. However, the number of microsleeps following sleep restriction was correlated with sleep efficiency (r?=?0.73, p?=?0.001), sleep onset latency (r?=??0.57, p?=?0.02), and sleep onset time-of-day standard deviation (r?=??0.54, p?=?0.03) over 11 normally rested nights. There was no correlation between PVT performance and the subsequent number of microsleeps during the tracking task in either session. Attributes usually associated with beneficial nighttime sleep patterns—going to sleep at a similar time each night, falling asleep quickly, and infrequent arousals—were related to greater vulnerability to microsleeps following sleep restriction. There were intercorrelations between all the sleep measures associated with microsleep rate following sleep restriction, indicating that the measures form a pattern of behaviors and are not independently related to microsleep rate. Perhaps some people maintain a regular sleep pattern because they experience sleepiness the following day when their pattern is disrupted. Conversely, people with more variation in their sleep pattern may do so because this does not substantially increase sleepiness the following day. We conclude that people with consistent sleep patterns and efficient sleep may be more prone to microsleeps than other people when their usual regular pattern is disrupted by sleep restriction.     

Variation and repeatability of ultrasonic sexual advertisement signals inAchroia grisella (Lepidoptera: Pyralidae)

MaleAchroia grisella (Lepidoptera: Pyralidae) produce ultrasonic advertisement signals for pair formation. The signals are generated by wing-fanning and consist of pairs of approximately 100-μs pulses of 70- to 130-kHz sound. In a previous study, playback experiments showed that femaleA. grisella preferred signals whose pulses were louder, longer, and delivered at a higher rate and included longer silent (asynchrony) intervals within pairs. To understand the variation and repeatability of these signal characters, acoustic signals of 18A. grisella males were recorded twice daily on the first 4 days and the seventh day after adult eclosion. ANOVA and MANOVA revealed significant among-individual and among-age variation for all signal characters. Peak amplitude, average amplitude, rate, and pulse length peaked 2–3 days after eclosion and then decreased. Asynchrony interval, however, continued to increase as males aged. Repeatabilities of peak amplitude, average amplitude, rate, and asynchrony interval were all relatively high (>0.5).     

Isolation of Malassezia globosa and M. sympodialis from patients with pityriasis versicolor in Spain

Pityriasis versicolor is a superficial infection of the stratum corneum by several yeast species formerly collectively named Malassezia furfur. The genus Malassezia has been recently enlarged with new species. With the exception of M. pachydermatis, the remaining six species have an absolute requirement in vitro for supplementation of long-chain fatty acids in media. These lipophilic yeasts comprise six species: M. furfur, M. globosa, M. obtusa, M. restricta, M. slooffiae and M. sympodialis. The aim of this study was to establish whether there was any association between the various species of Malassezia and pityriasis versicolor lesions. Thus, we studied the isolates from 79 patients with pityriasis versicolor, both from lesions and from apparently healthy skin close to the visible lesions. In pityriasis versicolor lesions, the species most frequently isolated was M. globosa (90%), followed by M. sympodialis (41%). Almost all isolates (99%) belonged to one of these two species. The most frequent pattern was M. globosa as the sole species (58% of cases), although the association with M. sympodialis was also frequent (30%). These results confirmed M. globosa as the main agent of pityriasis versicolor and M. sympodialis as the second agent in importance. Malassezia globosa was found to be a species with high levels of esterase and lipase enzymes of probable importance in their pathogenicity. This revised version was published online in June 2006 with corrections to the Cover Date.     

Sexual Dimorphism and Mortality Bias in a Small Miocene North American Rhino, <Emphasis Type="Italic">Menoceras arikarense</Emphasis>: Insights into the Coevolution of Sexual Dimorphism and Sociality in Rhinos

Rhinos are the only modern perissodactyls that possess cranial weapons similar to the horns, antlers and ossicones of modern ruminants. Yet, unlike ruminants, there is no clear relationship between sexual dimorphism and sociality. It is possible to extend the study of the coevolution of sociality and sexual dimorphism into extinct rhinos by examining the demographic patterns in large fossil assemblages. An assemblage of the North American early Miocene (∼22 million years ago) rhino, Menoceras arikarense, from Agate Springs National Monument, Nebraska, exhibits dimorphism in incisor size and nasal bone size, but there is no detectible dimorphism in body size. The degree of dimorphism of the nasal horn is greater than the degree of sexual dimorphism of any living rhino and more like that of modern horned ruminants. The greater degree of sexual dimorphism in Menoceras horns may relate to its relatively small body size and suggests that the horn had a more sex-specific function. It could be hypothesized that Menoceras evolved a more gregarious type of sociality in which a fewer number of males were capable of monopolizing a larger number of females. Demographic patterns in the Menoceras assemblage indicate that males suffered from a localized risk of elevated mortality at an age equivalent to the years of early adulthood. This mortality pattern is typical of living rhinos and indicates that young males were susceptible to the aggressive behaviors of dominant individuals in areas conducive to fossilization (e.g., ponds, lakes, rivers). Menoceras mortality patterns do not suggest a type of sociality different from modern rhinos although a group forming type of sociality remains possible. Among both living and extinct rhinos, the severity of socially mediated mortality seems unrelated to the degree of sexual dimorphism. Thus, sexual dimorphism in rhinos is not consistent with traditional theories about the co-evolution of sexual dimorphism and sociality.     

Restriction endonuclease digestion patterns of harvest mice (Reithrodontomys) chromosomes: a comparison to G-bands,C-bands,and in situ hybridization

Constitutive heterochromatin of a karyotypically conserved species of harvest mouse was compared to that of three karyotypically derived species of harvest mice by examining banding patterns produced on metaphase chromosomes with three restriction endonucleases (EcoRI, MboI and PstI). Banding patterns produced by two of these restriction endonucleases (EcoRI and MboI) were compared to published G- and C-banded karyotypes and in situ hybridization of a satellite DNA repeat for these taxa. The third restriction endonuclease (PstI) did not produce a detectable pattern of digestion. For the most part, patterns produced by EcoRI and MboI can be related to C-banded chromosomes and in situ hybridization of satellite DNA sequences. Moreover, digestion with EcoRI reveals bands not apparent with these other techniques, suggesting that restriction endonuclease digestion of metaphase chromosomes may provide additional insight into the structure and organization of metaphase chromosomes. The patterns produced by restriction endonuclease digestion are compatible with the chromosomal evolution of these taxa, documenting that in the highly derived taxa not only are the chromosomes rearranged but the abundance of certain sequences is highly variable. However, technical variation and difficulty in producing consistent results even on a single slide with some restriction endonucleases documents the problems associated with this method.     

Courtship and spawning sounds in bird wrasse Gomphosus varius and saddle wrasse Thalassoma duperrey

Acoustic signals from the bird wrasse Gomphosus varius and saddle wrasse Thalassoma duperrey were recorded on coral reefs in Hawaii. Terminal phase males in both species emit two types of pulse trains (type I and type II). Type I pulses were produced during spawning and courtship, while type II pulses were associated only with courtship behaviours. Gomphosus varius type I pulses were of lower frequency than T. duperrey type I pulses (271 v. 840 Hz) and were of narrower band. Discriminant function analyses revealed interspecific differences between type I pulse trains and individual pulses of both types. This study is the first documentation of courtship and spawning sounds in sympatric labrids and shows divergence in acoustic signals.     

Agonistic and grooming behavior of captive crowned lemurs (Lemur coronatus) during the breeding season

Captive breeding of rare and endangered prosimians may be enhanced by an increased understanding of all aspects of their seasonal mating behavior. In this study, the agonistic and grooming behaior of captiveL. coronatus were studied during their annual breeding season. Between October and March, selected aspects of agonistic and grooming behavior of four male-female groups were recorded. Males initiated significantly more allogrooming than females. The frequency of this behavior pattern increased significantly in the weeks of estrus. Females performed significantly more agonistic behavior patterns than males. The mean frequency of agonistic interactions decreased significantly during the breeding season. In successfully reproducing groups males showed much less agonism towards females, than they did in unsuccessful groups. Inter-specific comparisons demonstrated that the patterns of agonistic interactions during the breeding season are very different among closely related species of lemurids. The conclusions drawn from this study are that captive breeding of crowned lemurs may be enhanced by keeping permanent multi-male, multi-female groups.     

Temporal variation and characterization of grunt sounds produced by Atlantic cod Gadus morhua and pollack Pollachius pollachius during the spawning season

Fine‐scale temporal patterning in grunt production and variation in grunt attributes in Atlantic cod Gadus morhua and pollack Pollachius pollachius was examined. Pollachius pollachius produced only a single sound type, the grunt, similar to that previously described for G. morhua. Sound production and egg production were correlated in P. pollachius but not in G. morhua. Only G. morhua displayed a strongly cyclical pattern, producing more grunts at night. Finer‐scale temporal patterning in grunt production was observed in both species which produced significantly fewer grunts following a period of high grunt production. These quieter periods lasted up to 45 min for P. pollachius and up to 1 h in G. morhua. Grunts were not always produced in isolation but organized into bouts in both species. Longer bouts were more frequent during periods of increased sound activity and were linked with changes in grunt characteristics including increased grunt duration, pulse duration and repetition period of each pulse combined with decreased dominant frequency. This study provides the first evidence of acoustic signalling being used by spawning P. pollachius and presents the most detailed analysis of the complexity of gadoid sound production.     

Ecology of a bolas spider,Mastophora hutchinsoni: phenology,hunting tactics,and evidence for aggressive chemical mimicry

Summary Bolas spiders are relatively rare members of the large family known as orb weavers. Instead of using a typical web to capture prey, late-stadia and adult female bolas spiders swing a droplet of adhesive on a thread at flying insects. Mastophora hutchinsoni (Araneae: Araneidae) is one of five Mastophora species known from the United States and occurs over much of eastern North America. It is univoltine in Kentucky and overwinters in the egg stage. Spiderling emerged in May, the diminutive males matured in late June and early July, and females matured in early September. Eggs were produced from late September to late October or early November. This report is the first complete documentation of the population phenology of any bolas spider. Newly-emerged M. hutchinsoni spiderlings did not use a bolas, but instead hunted by positioning themselves on the underside of leaf margins where they ambushed small arthropods that crawled along the leaf margins. Subadult and adult female M. hutchinsoni used a bolas to capture moths. Only male moths were captured, specifically three species of Noctuidae (bristly cutworm, bronzed cutworm, and smoky tetanolita) and one species of Pyralidae (bluegrass webworm). Among 492 prey captured by more than twenty spiders at two sites during 1985 and 1986, smoky tetanolita moths and bristly cutworm moths accounted for 93% of the total. The flight behavior of approaching moths, the limited taxa caught from a large available moth fauna, and the fact that only males were caught support the hypothesis that the spider attracts its prey by producing chemicals which mimic the sex pheromones of these moth species. Adult female M. hutchinsoni frequently captured more than one moth species on a given night. The two most common prey species were active at different times of night, the bristly cutworm soon after nightfall and the smoky tetanolita generally between 11:00 p.m. and dawn. This pattern suggests that mating activity of these moth species may be temporally isolated, a common phenomenon when sympatric species have similar pheromones. If so, the spider could capture both species without producing different pheromone-mimicking compounds, simply by hunting during the activity period of each species.The investigation reported in this paper (No. 87-7-76) is in connection with a project of the Kentucky Agricultural Experiment Station and is published with the approval of the Director