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We use data from the 17th data release of the Apache Point Observatory Galactic Evolution Experiment (APOGEE 2) to contrast the chemical composition of the recently discovered Gaia Enceladus/Sausage system (GE/S) to those of ten Milky Way (MW) dwarf satellite galaxies: LMC, SMC, Bo\"otes I, Carina, Draco, Fornax, Sagittarius, Sculptor, Sextans and Ursa Minor. Our main focus is on the distributions of the stellar populations of those systems in the [Mg/Fe]-[Fe/H] and [Mg/Mn]-[Al/Fe] planes, which are commonly employed in the literature for chemical diagnosis and where dwarf galaxies can be distinguished from in situ populations. We show that, unlike MW satellites, a GE/S sample defined purely on the basis of orbital parameters falls almost entirely within the locus of "accreted" stellar populations in chemical space, which is likely caused by an early quenching of star formation in GE/S. Due to a more protracted history of star formation, stars in the metal-rich end of the MW satellite populations are characterized by lower [Mg/Mn] than those of their GE/S counterparts. The chemical compositions of GE/S stars are consistent with a higher early star formation rate than MW satellites of comparable and even higher mass, suggesting that star formation in the early universe was strongly influenced by other parameters in addition to mass. We find that the direction of the metallicity gradient in the [Mg/Mn]-[Al/Fe] plane of dwarf galaxies is an indicator of the early star formation rate of the system, Comment: MNRAS, in press. 13 pages, including 6 figures and 6 tables

Many animals communicate using complex signals composed of multiple components. In some, multiple distinct signal components are organized into stereotyped sequences. Few studies, however, have examined how such temporal structure might arise, or how this structural complexity relates to signal function. Male black widow spiders (Latrodectus hesperus) intermittently transition from a ‘haphazard’ production of three distinct vibratory signal components to a temporally structured multicomponent display during courtship. In this study, we examined the function of structured signalling during courtship in L. hesperus. More specifically, we examined whether structured signalling rates is predicted by male mass and whether structured signalling rates predict male mating success. Then, we experimentally tested the consequences of removing one of the signal components (abdominal tremulation) for male mating success. Larger males had lower signalling rates, suggesting a trade-off between structured signalling and mass. Males that produced structured signals more frequently mated sooner. Impairment of abdominal tremulation did not affect copulation success, but these ‘muted’ males took significantly longer to mate. Our study demonstrates that the temporal arrangement of signal components is important for male mating success in L. hesperus.

Invasive species are common around the world, but we still do not know which traits are most important for successfully establishing in new environments. Different stages of the invasion process, including transport, introduction, establishment, and spread, can act as selective filters for different combinations of phenotypic traits. Theoretical and empirical studies predict that invasive populations should have suites of behaviours that improve dispersal and spread, including higher boldness, dispersal propensity, and activity levels than native populations. In this study, we tested these predictions by comparing the morphology, life history, and behaviour of an invasive population of redback spiders, Latrodectus hasselti, from Japan to a population of native spiders from Australia, with additional comparisons of another invasive population from New Zealand. We found that both a longer-established invasive New Zealand population and the more recently-established invasive population from Japan were more dispersive than the native population from Australia. The invasive population from Japan showed elevated levels of sibling cannibalism relative to the native population, which may increase total reproductive success of females under food limitation. Spiders from Japan were also less bold in response to a simulated predator threat compared to native spiders from Australia. In contrast to the prediction that invasive populations would show uniformly fast life history traits, the invasive population from Japan was more fecund, yet took longer to develop than the native population under laboratory conditions. Overall, our results show that invasive populations are phenotypically distinct from native populations, with some behavioural, life history, and morphological traits that would increase spread (dispersal tendency, high fecundity) and persistence (sibling cannibalism) in new habitats.

Temperature challenges are one of the leading abiotic causes of success or failure of non-native species in a novel environment, and this is particularly true for low temperatures. Establishing and reproducing in a novel thermal environment can alter survival, behavior, and traits related to fitness. It has been proposed that plasticity or adaptation of thermal tolerance may allow an introduced species to thrive, or that successful invaders may be those with a thermal breadth in their native habitat that encompasses their new environment. Here, we tested these hypotheses using native and invasive populations of Australian redback spiders (Latrodectus hasselti). We measured how exposure to temperatures common to invasive and native range habitats (exposure to 15 and 25°C, respectively) affected behavioral and life-history traits and trade-offs that may underlie fitness in an invasive population detected in 1995 in Japan and a native population from Australia. We found that the critical thermal minimum (CTmin) was higher in the invasive population from Japan than in the native population, but critical thermal maximum (CTmax) did not differ between populations. Compared to the invasive population, eggs from the native population had a longer development time and lower hatching success at 15°C. Both populations performed equally well at 25°C, as measured by egg development time and hatching success. Invasive juveniles tested at 15°C were faster to explore a novel environment and bolder compared to those tested at 25°C. In comparison, the native population showed faster average exploration, with no differences in boldness or exploration at the two development or testing temperatures. Overall, L. hasselti from Japan maintained hatching success and development across a wider temperature range than the native population, indicating greater thermal breadth and higher behavioral plasticity. These results support the importance of plasticity in thermal tolerance and behavior for a successful invasion under novel environmental temperatures.

Motivated by recent developments suggesting that interaural coupling in non-mammals allows for the two active ears to effectively synchronize, this report describes otoacoustic measurements made in the oral cavity of lizards. As expected from that model, spontaneous otoacoustic emissions (SOAEs) were readily measurable in the mouth, which is contiguous with the interaural airspace. Additionally, finite element model calculations were made to simulate the interaural acoustics based upon SOAE-related tympanic membrane vibrational data. Taken together, these data support the notion of two active ears synchronizing by virtue of acoustic coupling and have potential implications for sound localization at low-levels.

It has been proposed that the globular cluster-like system Terzan 5 is the surviving remnant of a primordial building block of the Milky Way bulge, mainly due to the age/metallicity spread and the distribution of its stars in the $\alpha$-Fe plane. We employ Sloan Digital Sky Survey (SDSS-IV) data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE 2) to test this hypothesis. Adopting a random sampling technique, we contrast the abundances of 10 elements in Terzan 5 stars with those of their bulge field counterparts with comparable atmospheric parameters, finding that they differ at statistically significant levels. Abundances between the two groups differ by more than 1$\sigma$ in Ca, Mn, C, O, and Al, and more than 2$\sigma$ in Si and Mg. Terzan 5 stars have lower [$\alpha$/Fe] and higher [Mn/Fe] than their bulge counterparts. Given those differences, we conclude that Terzan 5 is not the remnant of a $major$ building block of the bulge. We also estimate the stellar mass of the Terzan 5 progenitor based on predictions by the Evolution and Assembly of GaLaxies and their Environments (EAGLE) suite of cosmological numerical simulations, concluding that it may have been as low as $\sim3\times10^8$ M$_\odot$ so that it was likely unable to significantly influence the mean chemistry of the bulge/inner disk, which is significantly more massive ($\sim10^{10}$ M$_\odot$). We briefly discuss existing scenarios for the nature of Terzan 5 and propose an observational test that may help elucidate its origin., Comment: 15 pages, 10 figures, accepted for publication by MNRAS

Insects are often small relative to the wavelengths of sounds they need to localize, which presents a fundamental biophysical problem. Understanding novel solutions to this limitation can provide insights for biomimetic technologies. Such an approach has been successful using the fly Ormia ochracea (Diptera: Tachinidae) as a model. O. ochracea is a parasitoid species whose larvae develop as internal parasites within crickets (Gryllidae). In nature, female flies find singing male crickets by phonotaxis, despite severe constraints on directional hearing due to their small size. A physical coupling between the two tympanal membranes allows the flies to obtain information about sound source direction with high accuracy because it generates interaural time-differences (ITD) and interaural level differences (ILD) in tympanal vibrations that are exaggerated relative to the small arrival-time difference at the two ears, that is the only cue available in the sound stimulus. In this study, I demonstrate that pure time-differences in the neural responses to sound stimuli are sufficient for auditory directionality in O. ochracea.

Body size is an important trait linking pollinators and plants. Morphological matching between pollinators and plants is thought to reinforce pollinator fidelity, as the correct fit ensures that both parties benefit from the interaction. We investigated the influence of body size in a specialized pollination system (buzz‐pollination) where bees vibrate flowers to release pollen concealed within poricidal stamens. Specifically, we explored how body size influences the frequency of buzz‐pollination vibrations. Body size is expected to affect frequency as a result of the physical constraints it places on the indirect flight muscles that control the production of floral vibrations. Larger insects beat their wings less rapidly than smaller‐bodied insects when flying, but whether similar scaling relationships exist with floral vibrations has not been widely explored. This is important because the amount of pollen ejected is determined by the frequency of the vibration and the displacement of a bee's thorax. We conducted a field study in three ecogeographic regions (alpine, desert, grassland) and recorded flight and floral vibrations from freely foraging bees from 27 species across four families. We found that floral vibration frequencies were significantly higher than flight frequencies, but never exceeded 400 Hz. Also, only flight frequencies were negatively correlated with body size. As a bee's size increased, its buzz ratio (floral frequency/flight frequency) increased such that only the largest bees were capable of generating floral vibration frequencies that exceeded double that of their flight vibrations. These results indicate size affects the capacity of bees to raise floral vibration frequencies substantially above flight frequencies. This may put smaller bees at a competitive disadvantage because even at the maximum floral vibration frequency of 400 Hz, their inability to achieve comparable thoracic displacements as larger bees would result in generating vibrations with lower amplitudes, and thus less total pollen ejected for the same foraging effort.

It is not uncommon to find courtship displays that incorporate numerous components across different sensory modalities. We studied displays in male jumping spiders of the genus Habronattus F.O. Pickard-Cambridge, 1901, which court females using a combination of ornament and motion (dance) displays coordinated with vibrational songs. To explore the diversity in Habronattus courtship complexity, we focused on quantifying the dance and vibratory displays in nine members of the Habronattus clypeatus species group, with preliminary observations on two additional species from this group. Additionally, we looked at display variation across populations in two widespread species from this group. We document three main courtship types: “stilting”, “buzzing”, and “spinning”, each identifiable by the presence or emphasis on particular display types. We found that for the widespread species H. clypeatus (Banks, 1895), different populations differed significantly and could be classified as either stilting or buzzing types. We discuss these results in relation to broader patterns of signal evolution and diversification in Habronattus.

Food forests are multilayered polycultures of mostly perennial species and an agroforestry practice well‐suited to the urban environment. They are gaining increasing attention in temperate regions of Europe and the United States, but, to date, there has been little research on them in the American Southwest. In this study, we visited 14 food forests, all but two of which were in urban or peri‐urban areas. At 12 of the food forests, we interviewed a person who established or manages them. The food forests span a significant range of the physical environments, types of communities, and ownerships found in the American Southwest. Despite challenges associated with the southwestern environment, such as the hot, dry climate and difficult soil conditions, we found clear evidence that food forests can be successfully established in the urban areas of this region. In addition to food production, these food forests are providing numerous other benefits such as mitigating the urban heat island effect, increasing local biodiversity, and improving the aesthetics of urban neighborhoods. While there is a need for additional research, a variety of networks and information sources have been established that are providing both practical information and inspiration for the establishment of additional food forests in the region.

Recent evidence based on APOGEE data for stars within a few kpc of the Galactic centre suggests that dissolved globular clusters (GCs) contribute significantly to the stellar mass budget of the inner halo. In this paper we enquire into the origins of tracers of GC dissolution, N-rich stars, that are located in the inner 4 kpc of the Milky Way. From an analysis of the chemical compositions of these stars we establish that about 30% of the N-rich stars previously identified in the inner Galaxy may have an accreted origin. This result is confirmed by an analysis of the kinematic properties of our sample. The specific frequency of N-rich stars is quite large in the accreted population, exceeding that of its in situ counterparts by near an order of magnitude, in disagreement with predictions from numerical simulations. We hope that our numbers provide a useful test to models of GC formation and destruction., Comment: 12 pages including 7 Figures and 1 Appendix. Accepted for publication by MNRAS

The contribution of dissolved globular clusters (GCs) to the stellar content of the Galactic halo is a key constraint on models for GC formation and destruction, and the mass assembly history of the Milky Way. Earlier results from APOGEE pointed to a large contribution of destroyed GCs to the stellar content of the inner halo, by as much as 25$\%$, which is an order of magnitude larger than previous estimates for more distant regions of the halo. We set out to measure the ratio between N-rich and normal halo field stars, as a function of distance, by performing density modelling of halo field populations in APOGEE DR16. Our results show that at 1.5 kpc from the Galactic Centre, N-rich stars contribute a much higher 16.8$^{+10.0}_{-7.0}$$\%$ fraction to the total stellar halo mass budget than the 2.7$^{+1.0}_{-0.8}$$\%$ ratio contributed at 10 kpc. Under the assumption that N-rich stars are former GC members that now reside in the stellar halo field, and assuming the ratio between first-and second-population GC stars being 1:2, we estimate a total contribution from disrupted GC stars of the order of 27.5$^{+15.4}_{-11.5}$$\%$ at r = 1.5 kpc and 4.2$^{+1.5}_{-1.3}$$\%$ at r = 10 kpc. Furthermore, since our methodology requires fitting a density model to the stellar halo, we integrate such density within a spherical shell from 1.5-15 kpc in radius, and find a total stellar mass arising from dissolved and/or evaporated GCs of $M_{\mathrm{GC,total}}$ = 9.6$^{+4.0}_{-2.6}$ $\times$ 10$^{7}$ M$\odot$., Paper accepted for Publication in MNRAS, correction of Fig 7

We report evidence from APOGEE for the presence of a new metal-poor stellar structure located within $\sim$4~kpc of the Galactic centre. Characterised by a chemical composition resembling those of low mass satellites of the Milky Way, this new inner Galaxy structure (IGS) seems to be chemically and dynamically detached from more metal-rich populations in the inner Galaxy. We conjecture that this structure is associated with an accretion event that likely occurred in the early life of the Milky Way. Comparing the mean elemental abundances of this structure with predictions from cosmological numerical simulations, we estimate that the progenitor system had a stellar mass of $\sim5\times10^8M_\odot$, or approximately twice the mass of the recently discovered Gaia-Enceladus/Sausage system. We find that the accreted:{\it in situ} ratio within our metal-poor ([Fe/H]$, Comment: Accepted for publication in MNRAS. 22 pages, 13 Figures

Floral sonication is a behaviour in which certain bees generate substrate-borne vibrations by contracting their flight muscles in order to extract pollen from poricidal anthers. Sonication vibratio...

Any sensory strategies that prey take to avoid eavesdropping predators will depend on the behavioral decisions of eavesdroppers. As these decisions are guided by the sensory processing of communication signals, accurate measurements of sensorimotor output will provide insights into signal preferences, parameters evaluated for signal recognition, and the perceptual and cognitive capacity of receivers. A number of techniques have been proposed for measuring walking phonotaxis (and taxis behavior more generally). Consistent limitations of such measures are (1) that some animals cannot discriminate alternative signals when they occur simultaneously (i.e., overlapping in the spectral and temporal domain), or (2) some animals respond with low selectivity to stimuli presented in isolation, and (3) identifying appropriate dimensions of response variability is not straightforward. Here we document an approach to develop a sensitive phonotaxis performance index to quantify pulse rate selectivity in two distinct populations of the acoustic parasitoid fly Ormia ochracea. Using a spherical treadmill to measure tethered walking phonotaxis, we examined the ability of flies to track a switch in the broadcast location of test songs with varying pulse-rates. By applying an information-theoretic approach, we identified a set of response parameters that best predict a previously described pulse-rate preference. These parameters were incorporated into an index to describe temporal pattern selectivity during walking phonotaxis. Our study also revealed that in Floridian Ormia ochracea, the pulse rate preference function is not affected by the locomotor mode (walking vs. flying) used in phonotaxis. Furthermore, we describe for the first time, pulse rate selectivity in Californian Ormia ochracea. Both populations have pulse rate preference functions with peak selectivity between 50 and 60 Pulses/s (pps). Previous studies demonstrating natural differences in host song preferences (Floridian O. ochracea preferring Gryllus rubens and Californian O. ochracea preferring Gryllus lineaticeps calling songs) may be based on other temporal parameters aside from pulse rate. Finally, we discuss the advantages and limitations of our approach in quantifying signal selectivity. This approach can be applied broadly to study signal preferences in other acoustic parasitoid flies and potentially other eavesdroppers that exhibit taxis behaviors in response to the communication signals of prey.

Spiders rely on mechanical vibration sensing for sexual signalling, prey capture and predator evasion. The sensory organs underlying vibration detection, called slit sensilla, resemble cracks in the spider's exoskeleton, and are distributed all over the spider body. Those crucial to sensing web- and other substrate-borne vibrations are called lyriform organs and are densely distributed around leg joints. It has been shown that forces that cause bending at leg joints also activate these lyriform organs. Little is known of how the biomechanics of the body of a freely-suspended spider in its natural posture interact with vibrations introduced into the body and how this affects vibration perception. Female black widow spiders, in particular, have a striking body-form; their long thin legs support a large pendulous abdomen. Here, we show that in their natural posture, the large abdominal mass of black widow females, interacts with the spring-like behaviour of their leg joints and determines the mechanical behaviour of different leg joints. Furthermore, we find that adopting different body postures enables females to alter both the level and tuning of the mechanical input to lyriform organs. Therefore, we suggest that posture may be used to flexibly and reversibly focus attention to different classes or components of web vibration. Postural effects thus emphasize the dynamic loop of interactions between behaviour and perception, i.e. between 'brain' and body.

For most spiders, their sensory world is dominated by their ability to detect vibrational stimuli. The organs responsible for detecting substrate vibrations are located on the animals’ extremities and known as lyriform organs, close aggregations of membrane-covered slits in the cuticular exoskeleton. The morphology and geometry of the lyriform organ is an important determinant of how it functions and the range of stimuli it can detect. Most work on the morphology, mechanics and physiology of lyriform organs has been conducted on adult wandering spiders, Cupiennius salei, and little is known about the morphology in other species or juveniles. We examine the morphology of the HS10 lyriform organ in both adult and juvenile Western black widows (Latrodectus hesperus). We find hypoallometric scaling of the lyriform organ and the size of individual slits when compared to body size. However, the cuticular pad distal to HS10 scales isometrically across successive instars. We also find an increase in the number of slits within the lyriform organ with each moult. Future work should address physiological responses of the organ across development, which could lead to a better understanding of the function of the cuticular pad and stimuli pertinent to the survival of little-studied juvenile spiders.

Insects have evolved a diversity of hearing organs specialized to detect sounds critical for survival. We report on a unique structure on butterfly wings that enhances hearing. The Satyrini are a diverse group of butterflies occurring throughout the world. One of their distinguishing features is a conspicuous swelling of their forewing vein, but the functional significance of this structure is unknown. Here, we show that wing vein inflations function in hearing. Using the common wood nymph, Cercyonis pegala , as a model, we show that (i) these butterflies have ears on their forewings that are most sensitive to low frequency sounds (less than 5 kHz); (ii) inflated wing veins are directly connected to the ears; and (iii) when vein inflations are ablated, sensitivity to low frequency sounds is impaired. We propose that inflated veins contribute to low frequency hearing by impedance matching.

Generated inside the inner ear, spontaneous otoacoustic emissions (SOAEs) are the most salient evidence for an “active” ear. These emissions propagate back through the middle and external ears, setting the tympanic membrane in motion such that it effectively acts as a “speaker”. Better characterization of this motion would be useful for the quantification of power produced by the associated active processes. Towards this end, we took a comparative approach, examining spontaneous activity in both a lizard (green anole, Anolis carolinensis) and an invertebrate (tree cricket, Oecanthus nigricornis). Using a laser Doppler vibrometer and sensitive OAE probe, we measured both tympanum motion and the acoustic output. For lizards, using a single point measurement system (whose focal point was not well localized), roughly similar behavior was observed in both the mechanical tympanum motion and the acoustic SOAE. For a relatively large spontaneous vibration peak (at 3.9 kHz) on the lizard tympanum, the amplitude of displacement was approximately 60 pm. Differences were however noted between SOAE and vibration, and several possible explanations for such are discussed. For the cricket, only “open” coupling of the microphone could be implemented. It was observed that while spontaneous vibration on the tympanum could be detected above the noise floor (single peak about 3-4 kHz, with displacements of 10-35 pm), SOAEs could not. When a stimulus was presented to a elicit a stimulus frequency emission (SFOAE) using a suppression paradigm, no residual could be detected either in the vibration or acoustic response. Lastly, when two tones were presented, distortions were readily observable in the tympanum motion but no acoustic DPOAEs were detected. It is suggested that the relatively small size of the cricket tympanum and open coupling employed could explain these inconsistencies (e.g., it is too small to effectively radiate acoustic power above the noise floor).Generated inside the inner ear, spontaneous otoacoustic emissions (SOAEs) are the most salient evidence for an “active” ear. These emissions propagate back through the middle and external ears, setting the tympanic membrane in motion such that it effectively acts as a “speaker”. Better characterization of this motion would be useful for the quantification of power produced by the associated active processes. Towards this end, we took a comparative approach, examining spontaneous activity in both a lizard (green anole, Anolis carolinensis) and an invertebrate (tree cricket, Oecanthus nigricornis). Using a laser Doppler vibrometer and sensitive OAE probe, we measured both tympanum motion and the acoustic output. For lizards, using a single point measurement system (whose focal point was not well localized), roughly similar behavior was observed in both the mechanical tympanum motion and the acoustic SOAE. For a relatively large spontaneous vibration peak (at 3.9 kHz) on the lizard tympanum, the amplitude of...

Some insects produce and use sound during multiple behaviors including many aspects of reproduction. Variation in call structure depends on the evolved morphological structures used to produce the sound and encode function. Beetles in the genus Nicrophorus produce stridulation by rubbing plectra, located on the ventral side of the elytra, against a pars stridens, located on the caudal end on the fourth and fifth abdominal segment in females and males, respectively. During field surveys for the endangered N. americanus, survey crews have historically used a small V-shaped notch cut in the caudal end of the right elytron to serves as a permanent marking method. No study, however, has examined the effect of this marking technique on the characters of stridulation or consequences for reproductive behavior and fitness. Here we show that one temporal and one spectral character of sound change significantly following elytron clipping, and that reproductive success is significantly decreased in all breedings in which a parent beetle is elytron-clipped. We recommend replacement of this marking technique with non-invasive methods to ensure conservation of this endangered species.

Male grigs, bush-crickets and field crickets produce mating calls by tegminal stridulation: the scraping together of modified forewings functioning as sound generators. Bush- (Tettigoniidae) and field-crickets (Gryllinae) diverged some 240 million years ago, with each lineage developing unique characteristics in wing morphology and the associated mechanics of stridulation. The grigs (Prophalangopsidae), a relict lineage more closely related to bush-crickets than to field-crickets, are believed to retain plesiomorphic features of wing morphology. The wing cells widely involved in sound production, such as the harp and mirror, are comparatively small, poorly delimited and/or partially filled with cross-veins. Such morphology is similarly observed in the earliest stridulating ensiferans, for which stridulatory mechanics remains poorly understood. The grigs, therefore, are of major importance to investigate the early evolutionary stages of tegminal stridulation, a critical innovation in the evolution of the Orthoptera. The aim of this study is to appreciate the degree of specialisation on grig forewings, through identification of sound radiating area areas and their properties. For well-grounded comparisons, homologies in wing venation (and associated areas) of grigs and bush-crickets are re-evaluated. Then, using direct evidence, this study confirms the mirror cell, in association with two other areas (termed ‘neck’ and ‘pre-mirror’), as the acoustic resonator in the grig Cyphoderris monstrosa. Despite the use of largely symmetrical resonators, as found in field-crickets, analogous features of stridulatory mechanics are observed between C. monstrosa and bush-crickets. Both morphology and function in grigs represents transitional stages between unspecialised forewings and derived conditions observed in modern species.

Male Tettigoniidae emit sound to attract conspecific females. The sound is produced by stridulation. During stridulation the forewings open and close, but it is during the closing stroke that the scraper contacts the file teeth to generate the predominant sound components, which are amplified by adjacent wing cells specialized in sound radiation. The sounds usually exceed the sonic boundary and might occur above 40 kHz, reaching extreme ultrasonic frequencies of 150kHz in some species. Here we test the hypothesis that Tettigoniidae species should prefer microhabitats that favour efficient signal transmission, i.e. that there is a relationship of sound frequency with the vertical distribution of the species (from ground to canopy) at Gorgona National Natural Park, Colombia. We sampled 16 trees and four different altitudinal levels between 1 and 20m above the understory vegetation. We placed collecting blankets separated by vertical distances of 5m, and knocked insects down using the technique known as fogging. We found no correlation between vertical distribution and carrier frequency, but there was a preference for open spaces (below the canopy and above the understory) in species using extreme ultrasound. This is the first quantitative description of the vertical distribution in neotropical species of the family Tettigoniidae and its relationship to the calling song frequency. Rev. Biol. Trop. 62 (Suppl. 1): 289-296. Epub 2014 February 01. Los machos de Tettigoniidae producen sonido frotando las alas anteriores para atraer a sus hembras coespecíficas con fines reproductivos (mecanismo conocido como estridulación). Un borde esclerotizado (o raspador) en el ala derecha es frotado sobre una vena modificada con dientecillos en el ala izquierda. Durante la estridulación las alas abren y cierran, pero es durante el cierre que el raspador contacta los dientecillos de la lima y produce vibraciones que son amplificadas por celdas adyacentes especializadas para radiar sonido. Sonidos que superen los 20 000Hz, se consideran ultrasónicos, en los Tettigoniidae, la mayoría de los cantos superan el umbral sónico y pueden ocurrir a más de 40 000Hz, con casos extremos de hasta 148 000Hz. La esencia de este trabajo es el estudio de esta gama espectacular de frecuencias de la familia Tettigoniidae y su relación con la distribución vertical de los individuos en las especies que habitan en Gorgona. Se muestrearon 16 árboles a cuatro niveles diferentes de altitud entre 1 y ~20m sobre el sotobosque, instalando sabanas colectoras a intervalos de 4-5m. Los insectos se colectaron mediante el método de nebulización térmica. El análisis indica que no hay correlación entre la distribución vertical de las especies y la frecuencia del canto. Sin embargo se observó una preferencia por espacios abiertos en especies que cantan a frecuencias extremas. Este estudio representa la primera descripción cuantitativa de la distribución vertical de Tettigoniidae Neotropicales y su relación con la frecuencia del canto.

Insects make use of sound in a variety of behavioral and reproductive contexts. Acoustic signals are known to serve in defense, sexual advertisement, prey location, and in cooperative activities such as offspring care and group foraging. In airborne signals produced by insects, information associated with species identification is often related to the temporal structure of the sound, while spectral quality is more closely associated with intraspecific variation. The Nicrophorine burying beetles (Insecta: Coleoptera: Silphidae) are a group known to produce sound through dorso-ventro stridulation, but the bioacoustics of this group remains understudied. Here, we examine the stridulatory sound produced by eight North American species of Nicrophorus burying beetles, testing the hypothesis that interspecific differences will be encoded in temporal characteristics of the sound, and that signal divergence will be explained by one of three mechanisms: selection as an intraspecific signal, selection for interspecific aposematism, or random divergence through drift. We digitally recorded stridulation in each species, and analyzed recordings to describe each in respect to four spectral and eight temporal acoustic characters. All species produced a low amplitude biphastic sound pulse consisting of from 58 to 126 syllables, and exhibiting weak dominant frequencies (5.8–12.7 kHz). Collapsing the 12 variables into three rotated factors using principal component analysis, we found no sex-related differences in sound, but significant interspecies divergence in respect to all three factors. We constructed a phylogeny for the group based on the morphology of the stridulatory structures and the acoustic characters, and found weak support for an intraspecific signal divergence model.

Male grigs, bush crickets and crickets produce mating calls by tegminal stridulation: the scraping together of modified forewings functioning as sound generators. Bush crickets (Tettigoniidae) and crickets (Gryllinae) diverged some 240 million years ago, with each lineage developing unique characteristics in wing morphology and the associated mechanics of stridulation. The grigs (Prophalangopsidae), a relict lineage more closely related to bush crickets than to crickets, are believed to retain plesiomorphic features of wing morphology. The wing cells widely involved in sound production, such as the harp and mirror, are comparatively small, poorly delimited and/or partially filled with cross-veins. Such morphology is similarly observed in the earliest stridulating ensiferans, for which stridulatory mechanics remains poorly understood. The grigs, therefore, are of major importance to investigate the early evolutionary stages of tegminal stridulation, a critical innovation in the evolution of the Orthoptera. The aim of this study is to appreciate the degree of specialization on grig forewings, through identification of sound radiating areas and their properties. For well-grounded comparisons, homologies in wing venation (and associated areas) of grigs and bush crickets are re-evaluated. Then, using direct evidence, this study confirms the mirror cell, in association with two other areas (termed 'neck' and 'pre-mirror'), as the acoustic resonator in the grig

Tree cricket males produce tonal songs, used for mate-attraction and male-male interactions. Active mechanics tunes hearing to conspecific song frequency. However, tree cricket song frequency increases with temperature, presenting a problem for tuned listeners. We show that the actively amplified frequency increases with temperature, thus shifting mechanical and neuronal auditory tuning to maintain a match with conspecific song frequency. Active auditory processes are known from several taxa, but their adaptive function has rarely been demonstrated. We show that tree crickets harness active processes to ensure that auditory tuning remains matched to conspecific song frequency, despite changing environmental conditions and signal characteristics. Adaptive tuning allows tree crickets to selectively detect potential mates or rivals over large distances and is likely to bestow a strong selective advantage by reducing mate-finding effort and facilitating intermale interactions.

Insects are the most diverse taxonomic group of animals, and this is reflected in the number and variety of anatomically and evolutionarily distinct ears to be found within this group. In general terms, all auditory systems must accomplish the same basic tasks of detecting, discriminating, and localizing sound sources. Insects, therefore, present many examples of alternative mechanisms for fundamental auditory processes, and research on insect auditory systems addresses all aspects of hearing and acoustic behavior. This research is also highly integrative. Insects provide important models for studies of biophysical and molecular mechanisms of auditory transduction. The relative simplicity of insect nervous systems (compared with those of vertebrates) allows for auditory mechanisms to be studied at the level of explicitly resolved neural circuits and identifiable neurons, and these can be linked to specific behavioral functions.

Jumping spiders in the genus Habronattus use complex multimodal signals during courtship displays. In the present study, we describe multimodal displays from the Habronattus coecatus clade, comprising a diverse group of 23 described species. Habronattus coecatus group displays are made up of sex-specific ornamentation and temporally coordinated combinations of motion displays and vibratory songs. Vibratory songs are complex, consisting of up to 20 elements organized in functional groupings (motifs) that change as courtship progresses. This temporal structuring of displays is analogous to a musical composition. Vibratory elements are associated with movement displays involving coloured and patterned ornaments on the male body. We describe general patterns of multimodal displays for 11 species including one, Habronattus borealis, which appears to have lost complex display behaviour. Habronattus coecatus group courtship is one of the most complex communication systems yet described in arthropods and this group may reveal important factors driving the evolution of complex signals. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105, 522–547.

This paper describes Artiotonus, a new genus of tropical katydid from Colombia and Ecuador. These acoustic ensiferans are represented by three species with a geographic distribution generally restricted to the rainforest of the Bolivar geosyncline of northwestern South America (Pacific). A phylogenetic analysis based on 28 morphological and six behavioural characters produced a tree (A. artius, (A. tinae, A. captivus)) with a consistency index of 0.9. All species are defined by a few autapomorphic changes. The most reliable character for identification is the temporal pattern of the calling song, suggesting a recent genetic divergence. Biogeographic analysis indicates that such genetic divergence began with geographic isolation produced before the Holocene transgression. Species of this genus are remarkable in that the calling song of males exhibits a narrow spectrum with a high quality factor (37–42), unusual values for such ultrasonic signals. A broad discussion on the evolution of tonal calls and pulse...

Several conceptual models seek to explain patterns of male display and factors that influence female mate choice in lek mating systems. The central advantage model predicts that males displaying at or near the lek centre should be more attractive to females than are males positioned along the lek periphery. Females may exhibit biases toward these centrally displaying males based on either spatial or display-related cues. We tested the prediction of the central advantage model in investigating the importance of male display position in the subterranean and lek mating prairie mole cricket (Gryllotalpa major). Gryllotalpa major males form mating aggregations in the early spring and produce an acoustic advertisement signal from a constructed calling chamber at the soil surface. Pair formation occurs in the calling chamber, and males typically maintain these structures for the duration of the reproductive season. To assess whether G. major females exhibit a preference for males calling from centrally located acoustic burrows, we documented the spatial position and number of female attractions for all advertising males across the focal lek. Six spatial attributes related to display position were reduced using principal component analysis and examined for an association with male attractiveness. We found that in general, female attractions were distributed randomly across the lek; male attractiveness was not related to proximity to the lek centre nor to any factor associated with display position. The most highly attractive males, however, were located further from the lek centre and from nearest calling neighbours than other attractive males. Advertising males that segregate themselves within the aggregation and locate nearer the lek margin may gain a geometric advantage resulting in the increased probability of attracting a searching female.

Recently, work has shown that multimodal communication is common throughout the animal kingdom but the function of multimodal signals is still poorly understood. Phidippus clarus are jumping spiders in which males produce multimodal (visual and vibrational) signals in both male-male (aggressive) and male-female (courtship) contexts. The P. clarus mating system is complex, with sex ratios and the level of male competition changing over the course of the breeding season. Vibrational signal components have been shown to function in male aggressive contests but their role in courtship has not been investigated. Here, we performed an experiment to test the role of vibrational signaling in courtship by observing mating success for males that were experimentally muted. We show that vibratory courtship signals, and in particular signaling rate, is an important component of mating success and potentially a target of female choice. While the ability to produce vibratory signals significantly increased mating success, some muted males were still able to successfully mate. In these trials, signaling rate also predicted mating success suggesting that redundant signal components may compensate for errors and perturbations in signal transmission or that vibratory signals function to enhance the efficacy of visual signals.

The environment can impose strong limitations on the efficacy of signal transmission. In particular, for vibratory communication, the signaling environment is often extremely heterogeneous at small scales. Nevertheless, natural selection is expected to select for signals well-suited for effective transmission. Here, we test for substrate-dependent signal efficacy in the wolf spider Schizocosa stridulans Stratton 1991. We first explore the transmission characteristics of this important signaling modality by playing recorded substrate-borne signals through three different substrates (leaf litter, pine litter, and red clay) and measuring the propagated signal. We found that the substrate-borne signal of S. stridulans attenuates the least on leaf litter, the substrate upon which the species is naturally found. Next, by assessing mating success with artificially muted and non-muted males across different signaling substrates (leaf litter, pine litter, and sand), we explored the relationship between substrate-borne signaling and signaling substrate for mating success. We found that muted males were unsuccessful in obtaining copulations regardless of substrate, while mating success was dependent on the signaling substrate for non-muted males. For non-muted males, more males copulated on leaf litter than any other substrate. Taken together, these results confirm the importance of substrate- borne signaling in S. stridulans and suggest a match between signal properties and signal efficacy – leaf litter transmits the signal most effectively and males are most successful in obtaining copulations on leaf litter.

The environment can impose strong limitations on the efficacy of signal transmission. In particular, for vibratory communication, the signaling environment is often extremely heterogeneous at very small scales. Nevertheless, natural selection is expected to select for signals well-suited to effective transmission. Here, we test for substrate-dependent signal efficacy in the wolf spider Schizocosa stridulans Stratton 1991. We first explore the transmission characteristics of this important signaling modality by playing recorded substrate-borne signals through three different substrates (leaf litter, pine litter, and red clay) and measuring the propagated signal. We found that the substrate-borne signal of S. stridulans attenuates the least on leaf litter, the substrate upon which the species is naturally found. Next, by assessing mating success with artificially muted and non-muted males across different signaling substrates (leaf litter, pine litter, and sand), we explored the relationship between substrate-borne signaling and substrate for mating success. We found that muted males were unsuccessful in obtaining copulations regardless of substrate, while mating success was dependent on the signaling substrate for non-muted males. For non-muted males, more males copulated on leaf litter than any other substrate. Taken together, these results confirm the importance of substrate-borne signaling in S. stridulans and suggest a match between signal properties and signal efficacy – leaf litter transmits the signal most effectively and males are most successful in obtaining copulations on leaf litter [Current Zoology 56 (3): 370–378, 2010].

Tree cricket males produce tonal songs, which are used to attract mates and to interact with other males. In other crickets, the mechanical properties of their peripheral auditory system have evolved to have resonant modes at the communication frequency. The tree cricket auditory system, however, is not passively tuned to song frequency. Tree crickets exploit an active amplification process to tune hearing to song frequency. However, their song frequency increases with temperature, presenting a problem for tuned listeners. We show here that the actively amplified frequency increases with temperature, and shifts mechanical and neuronal auditory tuning to maintain a match with changing song frequency. We also find that in tree crickets active amplification does not provide greater sensitivity or dynamic range than that observed in other crickets that lack active amplification. Thus, the primary adaptive function of active amplification is to ensure that auditory tuning remains matched to conspecific song frequency, despite changing environmental conditions and signal characteristics.Tree cricket males produce tonal songs, which are used to attract mates and to interact with other males. In other crickets, the mechanical properties of their peripheral auditory system have evolved to have resonant modes at the communication frequency. The tree cricket auditory system, however, is not passively tuned to song frequency. Tree crickets exploit an active amplification process to tune hearing to song frequency. However, their song frequency increases with temperature, presenting a problem for tuned listeners. We show here that the actively amplified frequency increases with temperature, and shifts mechanical and neuronal auditory tuning to maintain a match with changing song frequency. We also find that in tree crickets active amplification does not provide greater sensitivity or dynamic range than that observed in other crickets that lack active amplification. Thus, the primary adaptive function of active amplification is to ensure that auditory tuning remains matched to conspecific song fr...

The jumping spider Phidippus clarus uses signals that combine visual and substrate-borne vibrations, which predict the outcome of male–male competition and are important to copulation success. We investigated the function of males’ substrate-borne vibrations by examining phenotypic correlates of vibratory signal traits and assessing whether these affect female mating and remating decisions. Virgin females were first paired with males, and females that copulated in first trials were then paired with a second male to determine whether females remate. We measured vibratory signals produced by males during these interactions to determine 1) correlations between substrate-borne signal traits and male phenotypes, 2) whether properties of substrate-borne signals predicted mating success in first and second copulations, and 3) whether females of different mating status have different acceptance thresholds for male characters. Courtship vibration rate was positively correlated with male leg size, and signaling rate significantly predicted mating success in all copulations. Some females were polyandrous; however, copulation with mated females occurred after longer courtship durations, and courtship duration was positively correlated with male size, demonstrating that mated females are less receptive to mates and suggesting that females may be trading up in subsequent matings. Our study shows that males invest significant effort in courtship and that sexual selection via female choice may play a nontrivial role in the mating system. These results are the first to show that honest information about male size is encoded by substrate vibrations, and these signals are important for male mating success in both virgin and mated females. Key words: female mating status, honest indicator, jumping spiders, mate choice, Phidippus, polyandry, sexual selection, substrate-borne vibrations. [Behav Ecol]

Opponent asymmetries often determine the probability of winning a fight in agonistic situations. In many animal systems, the asymmetries that drive the dynamics and outcome of male—male contests are related to resource holding potential (RHP) or territory ownership. However, recent studies have shown that this is not the case among females and suggest that resource valuation may be more important in that context. We studied contests between the female jumping spider, Phidippus clarus, and compared them with male–male contests in this same species. Our observations document several key differences between the sexes: Precontact and contact phases are longer in females, ritualized displays are rare in females but common among males, and female fights are more likely to end in injury or death. In sharp contrast with male contests, female weight and size do not correlate with signaling behavior, and the outcome of fights is predicted by differences in resource valuation rather than RHP. We interpret these differences in light of the different natural history of the sexes and discuss how the economics of fighting may lead to the evolution of ritualized displays in males and a ‘‘desperado effect’’ in females. Key words: divisive asymmetry, female—female competition, game theory, jumping spider, resource holding potential, resource potential value. [Behav Ecol]

In many animal taxa, prior contest experience affects future performance such that winning increases the chances of winning in the future (winner effect) and losing increases the chances of losing in the future (loser effect). It is, however, not clear whether this pattern typically arises from experience effects on actual or perceived fighting ability (or both). In this study, we looked at winner and loser effects in the jumping spider Phidippus clarus. We assigned winning or losing experience to spiders and tested them against opponents of similar fighting ability in subsequent contests at 1-, 2-, 5-, and 24-h intervals. We examined the strength of winner and loser effects, how long effects persist, as well as how experience affected perceived and actual fighting ability. Our results demonstrate that winner and loser effects are of approximately the same magnitude, although loser effects last longer than winner effects. Our results also demonstrate that previous experience alters actual fighting ability because both the assessment and escalation periods were affected by experience. We suggest that the retention time of experience effects depends on expected encounter rates as well as other behavioral and ecological factors. In systems with short breeding seasons and/or rapidly fluctuating populations, context-dependent retention of experience effects may allow males to track their status relative to the fluctuating fighting ability of local competitors without paying the costs necessary to recall or assess individual competitors. Copyright 2010, Oxford University Press.

Localizing individual sound sources under reverberant environmental conditions can be a challenge when the original source and its acoustic reflections arrive at the ears simultaneously from different paths that convey ambiguous directional information. The acoustic parasitoid fly Ormia ochracea (Diptera: Tachinidae) relies on a pair of ears exquisitely sensitive to sound direction to localize the 5-kHz tone pulsatile calling song of their host crickets. In nature, flies are expected to encounter a complex sound field with multiple sources and their reflections from acoustic clutter potentially masking temporal information relevant to source recognition and localization. In field experiments, O. ochracea were lured onto a test arena and subjected to small random acoustic asymmetries between 2 simultaneous sources. Most flies successfully localize a single source but some localize a ‘phantom’ source that is a summed effect of both source locations. Such misdirected phonotaxis can be elicited reliably in laboratory experiments that present symmetric acoustic stimulation. By varying onset delay between 2 sources, we test whether hyperacute directional hearing in O. ochracea can function to exploit small time differences to determine source location. Selective localization depends on both the relative timing and location of competing sources. Flies preferred phonotaxis to a forward source. With small onset disparities within a 10-ms temporal window of attention, flies selectively localize the leading source while the lagging source has minimal influence on orientation. These results demonstrate the precedence effect as a mechanism to overcome phantom source illusions that arise from acoustic reflections or competing sources.