Mate guarding and male mate choice in the chameleon grasshopper <Emphasis Type="Italic">Kosciuscola tristis</Emphasis> (Orthoptera: Acrididae)

In the wild, male chameleon grasshoppers (Kosciuscola tristis) are frequently observed mounted on the back of females even when not in copula, and will fight off other usurping males. If this behaviour is mate guarding and reflects investment in male mate choice, then we expect males to preferably guard females based on reliable cues of quality. Cues for female quality likely include female size and egg development that together may indicate fecundity. We investigated male mate choice in the field expressed as mate-guarding preference, by comparing size and egg development in guarded and unguarded females. We found no difference between guarded and unguarded females in measures of fecundity or body size. The majority of females sampled did not contain any viable eggs. This finding suggests that male K. tristis indiscriminately guard females in a scramble mating system.     

Experimental Manipulation of Melanism Demonstrates the Plasticity of Preferred Temperature in an Agricultural Pest (Phaulacridium vittatum)

Phenotypic plasticity is a key trait of successful pest species, and may increase the ability to cope with higher, more variable temperatures under climate change. We investigate the plasticity of preferred temperature in a widespread agricultural pest, the wingless grasshopper (Phaulacridium vittatum). Preferred temperature is a measure of thermoregulatory behaviour through habitat selection. It is influenced by melanism, which affects body temperature by determining the amount of radiation absorbed by the body. First we demonstrate that body temperature and preferred temperature in P. vittatum is influenced by melanism, by comparing the preferred temperature of the colour morphs in laboratory thermal gradients and field body temperatures in natural populations. We then test whether preferred temperature changes in response to changes in body temperature, by determining preferred temperature before and after manipulation of melanism by painting. When melanism was manipulated experimentally in live grasshoppers, preferred temperature changed to reflect the thermal qualities of the new colour. The preferred temperature of light grasshoppers increased after they were painted black, and decreased after being painted white. Similarly, dark individuals that were painted white behaved like a light individual, maintaining a lower body temperature. Preferred temperature in P.vittatum is a plastic thermoregulatory response to ambient temperature, mediated by the influence of melanism on body temperature.     

Elevational partitioning in species distribution,abundance and body size of Australian alpine grasshoppers (Kosciuscola)

Changes in the physical environment with elevation can influence species distributions and their morphological traits. In mountainous regions, steep temperature gradients can result in patterns of ecological partitioning among species that potentially increases their vulnerability to climate change. We collected data on species distributions, relative abundance and body size for three grasshopper species of the genus Kosciuscola (K. usitatus, K. tristis and K. cognatus) at three locations within the mountainous Kosciuszko National Park in Australia (Thredbo, Guthega and Jagungal). All three species showed differences in their distributions according to elevation, with K. usitatus ranging from 1400 to 2000 m asl, K. tristis from 1600 to 2000 m asl and K. cognatus from 1550 to 1900 m asl. Decreasing relative abundance with increasing elevation was found for K. usitatus, but the opposite pattern was found for K. tristis. The relative abundance of K. cognatus did not change with elevation but was negatively correlated with foliage cover. Body size decreased with elevation in both male and female K. usitatus, which was similarly observed in female K. tristis and male K. cognatus. Our results demonstrate spatial partitioning of species distributions and clines in body size in relation to elevational gradients. Species‐specific sensitivities to climatic gradients may help to predict the persistence of this grasshopper assemblage under climate change.     

Ferocious Fighting between Male Grasshoppers

Contests among individuals over mating opportunities are common across diverse taxa, yet physical conflict is relatively rare. Due to the potentially fatal consequences of physical fighting, most animals employ mechanisms of conflict resolution involving signalling and ritualistic assessment. Here we provide the first evidence of ubiquitous escalated fighting in grasshoppers. The chameleon grasshopper (Kosciuscola tristis) is an Australian alpine specialist, in which males engage in highly aggressive combat over ovipositing females. We describe discrete agonistic behaviours including mandible flaring, mounting, grappling, kicking and biting, and their use depending on the individual’s role as challenger or defender. We show that male role predicts damage, with challengers being more heavily damaged than males defending females (defenders). Challengers also possess wider mandibles than defenders, but are similar in other metrics of body size. Our data suggest that fights escalate between males matched in body size and that mandibles are used as weapons in this species. This system represents an exciting opportunity for future research into the evolution of costly fighting behaviour in an otherwise placid group.     

New case of long-term persistence of Paranosema locustae (Microsporidia) in melanopline grasshoppers (Orthoptera: Acrididae: Melanoplinae) of Argentina

We report an additional case of long-term persistence of Paranosema locustae in grasshoppers of Argentina. The pathogen was introduced from North America on rangeland at Loncopué, Neuquén province. Microsporidia were not detected in pre-introduction samples whereas infected grasshoppers were found 11 years after introduction. Affected grasshoppers were the melanoplines Dichroplus elongatus, Dichroplus maculipennis, and Scotussa lemniscata, some of them with high spore loads. The case highlights the ability of P. locustae to recycle in local grasshopper communities by parasitizing susceptible species other than the natural hosts.     

Temperature,but Not Available Energy,Affects the Expression of a Sexually Selected Ultraviolet (UV) Colour Trait in Male European Green Lizards

Background

Colour signals are widely used in intraspecific communication and often linked to individual fitness. The development of some pigment-based (e.g. carotenoids) colours is often environment-dependent and costly for the signaller, however, for structural colours (e.g. ultraviolet [UV]) this topic is poorly understood, especially in terrestrial ectothermic vertebrates.

Methodology/Principal Findings

In a factorial experiment, we studied how available energy and time at elevated body temperature affects the annual expression of the nuptial throat colour patch in male European green lizards (Lacerta viridis) after hibernation and before mating season. In this species, there is a female preference for males with high throat UV reflectance, and males with high UV reflectance are more likely to win fights. We found that (i) while food shortage decreased lizards'' body condition, it did not affect colour development, and (ii) the available time for maintaining high body temperature affected the development of UV colour without affecting body condition or other colour traits.

Conclusions/Significance

Our results demonstrate that the expression of a sexually selected structural colour signal depends on the time at elevated body temperature affecting physiological performance but not on available energy gained from food per se in an ectothermic vertebrate. We suggest that the effect of high ambient temperature on UV colour in male L. viridis makes it an honest signal, because success in acquiring thermally favourable territories and/or effective behavioural thermoregulation can both be linked to individual quality.     

Chameleons communicate with complex colour changes during contests: different body regions convey different information

Many animals display static coloration (e.g. of feathers or fur) that can serve as a reliable sexual or social signal, but the communication function of rapidly changing colours (as in chameleons and cephalopods) is poorly understood. We used recently developed photographic and mathematical modelling tools to examine how rapid colour changes of veiled chameleons Chamaeleo calyptratus predict aggressive behaviour during male–male competitions. Males that achieved brighter stripe coloration were more likely to approach their opponent, and those that attained brighter head coloration were more likely to win fights; speed of head colour change was also an important predictor of contest outcome. This correlative study represents the first quantification of rapid colour change using organism-specific visual models and provides evidence that the rate of colour change, in addition to maximum display coloration, can be an important component of communication. Interestingly, the body and head locations of the relevant colour signals map onto the behavioural displays given during specific contest stages, with lateral displays from a distance followed by directed, head-on approaches prior to combat, suggesting that different colour change signals may evolve to communicate different information (motivation and fighting ability, respectively).     

Thermoregulation in male western cicada killers (Sphecius grandis Say) in the Chihuahuan desert

(1) Male western cicada killers (Sphecius grandis) had elevated, apparently regulated, thorax temperatures during territorial patrolling. (2) Abdomen temperature increased steeply with increasing ambient temperature, approaching thorax temperature when ambient temperature exceeded 35 °C. (3) Both indirect evidence and heating experiments demonstrated the apparent ability to shunt heat from thorax to abdomen. (4) Dead, dry wasps reached lethal temperatures when placed in full sunlight on the bare ground, and substantially lower temperatures on plants. (5) The percentage of males perching was extremely low, occurring primarily during early morning hours. Most perching occurred on plants, and very little on the ground. (6) In contrast to what has been reported for eastern cicada killers (Sphecius speciosus), S. grandis males did not appear to use sophisticated behaviors to regulate body temperature during territorial defense, relying primarily on physiological mechanisms. (7) This strategy may be more appropriate for S. grandis in the hotter, drier environment of the lowland Chihuahuan desert.     

Effect of temperature on spontaneous interneuron activity in grasshoppers Tettigonia cantans and Metrioptera roeselii (Orthoptera, Tettigoniidae)

Using electrophysiological methods, effects of temperature on rhythmic impulsation of spontaneously active neurons of thoracic ganglia was studied in grasshoppers Tettigonia cantans and Metrioptera roeselii. Several types of response to temperature changes were observed. Its elevation caused an increase or decrease of the discharge dispersion and a gradual, proportional or abrupt rise of the impulse rate. On decreasing temperature, the impulsation usually returned to its original state, although sometimes at different rate. In neurons whose impulse rate was close to that of pulse repetition rate in male advertisement calls, this dependence was preserved at temperature changes. On the whole, there is reason to believe that changes of temperature in CNS are accompanied not only by a simple change of the neuronal activity level, but also by a complex readjustment in the neuronal network functioning, which allow preserving optimal level of insect metabolic processes and adequate behavior.     

Selection for social signalling drives the evolution of chameleon colour change

Rapid colour change is a remarkable natural phenomenon that has evolved in several vertebrate and invertebrate lineages. The two principal explanations for the evolution of this adaptive strategy are (1) natural selection for crypsis (camouflage) against a range of different backgrounds and (2) selection for conspicuous social signals that maximise detectability to conspecifics, yet minimise exposure to predators because they are only briefly displayed. Here we show that evolutionary shifts in capacity for colour change in southern African dwarf chameleons (Bradypodion spp.) are associated with increasingly conspicuous signals used in male contests and courtship. To the chameleon visual system, species showing the most dramatic colour change display social signals that contrast most against the environmental background and amongst adjacent body regions. We found no evidence for the crypsis hypothesis, a finding reinforced by visual models of how both chameleons and their avian predators perceive chameleon colour variation. Instead, our results suggest that selection for conspicuous social signals drives the evolution of colour change in this system, supporting the view that transitory display traits should be under strong selection for signal detectability.     

Temperature Effects on the Transmission of Bursaphelenchus xylophilus (Nemata: Aphelenchoididae) by Monochamus alternatus (Coleoptera: Cerambycidae)

The object of this research was to investigate the effects of ambient temperature on the transmission of the pinewood nematode, Bursaphelenchus xylophilus, by its vector, Monochamus alternatus. Ninety M. alternatus were reared individually at one of three constant temperatures (16, 20, and 25 °C). As the ambient temperature decreased from 25 to 16 °C, longevity of vectors decreased, nematode transmission efficiency decreased, and the peak period of nematode transmission was delayed and its peak height decreased. Low temperature may inhibit the transmission process, and this inhibition could be partially responsible for preventing pine wilt disease from devastating pine forests in cool regions.     

Leaves may function as temperature sensors in the heterophylly of Rorippa aquatica (Brassicaceae)

Many plants show heterophylly, which is variation in leaf form within a plant owing to environmental change. The molecular mechanisms underlying heterophylly have recently been investigated in several plant species. However, little is known about how plants exhibiting heterophylly sense environmental cues. Here, we used Rorippa aquatica (Brassicaceae), which shows heterophylly, to investigate whether a single leaf can sense and transit changes in ambient temperature. The morphology of newly developed leaves after single-leaf warming treatment was significantly different from that of mock-treated control leaves, suggesting that leaves are sensing organs that mediate the responses to changes in ambient temperature in R. aquatica.     

Physiological control of the chromatophores of Austrolestes annulosus (Odonata)

The chromatophore-containing integument of Austrolestes annulosus always changes from a dark to a blue colour phase in vitro and therefore functions independently of a central control mechanism. In isolated abdominal segments, the reverse colour change occurs independently of the presence of central nervous system. The amount of change decreases with the size of the piece of integument; it varies over different parts of the body of the same intact insect, and it varies both in vitro and in vivo with time of day.A variety of experiments, involving ligation of abdominal segments and ablation of their ganglia, show that the terminal ganglion is primarily responsible for the release of a darkening factor which migrates in an anterior direction. Other ventral ganglia have a similar function but are of less importance.Transplants of terminal ganglia and injection of their extracts fail to restore capacity for colour change in ligature-isolated segments which have had their own ganglia removed. These findings, supported by histological observations, suggest that the darkening factor is a neurosecretion.     

Conservation of a phenomenon: rapid,reversible colour change in both sexes of one of the world’s most threatened damselflies

Physiological colour change is rare in insects. Unusually, both the males and females of Spesbona angusta (Odonata: Platycnemididae), Red Listed as Endangered, are capable of rapid and reversible colour change. There is only one known population of this species, which occurs in a unique habitat in the Cape Floristic Region, South Africa. Appreciation of this unusual phenomenon of distinct physiological colour change helps us appreciate that we need to conserve phenomena in the insect world as well as the species themselves. Using controlled experiments, we evaluated the importance of ambient temperature as the possible primary cue for physiological colour change. We found that S. angusta responds rapidly to short-term changes in ambient temperature, even in the absence of additional environmental stimuli and without the body temperature matching the ambient temperature. Colour change is reversible when temperature returns to its earlier level. The reason why S. angusta shows this rapid and reversible colour change may be a combination of reproductive enhancement, competitive advantage and thermoregulation. This colour change appears to have strong selective advantage in a very particular habitat type, meaning that careful conservation of its habitat in all respects is important, and must be considered in any possible future translocations.     

Body size influences differently the detectabilities of colour morphs of cryptic prey

Body size and coloration may contribute to variation in performance and fitness among individuals; for example, by influencing vulnerability to predators. Yet, the combined effect of size and colour pattern on susceptibility to visual predators has received little attention, particularly in camouflaged prey. In the colour polymorphic pygmy grasshopper Tetrix subulata (Linnaeus, 1758), females are larger than males, although there is a size overlap between sexes. In the present study, we investigated how body size and colour morph influenced detection of these grasshoppers, and whether differences in protective value among morphs change with size. We conducted a computer‐based experiment and compared how human ‘predators’ detected images of large, intermediate or small grasshoppers belonging to black, grey or striped colour morphs when embedded in photographs of natural grasshopper habitats. We found that time to detection increased with decreasing size, that differences in time to detection of the black, grey and striped morphs depended differently on body size, and that no single morph provided superior or inferior protection in all three size classes. By comparing morph frequencies in samples of male and female grasshoppers from natural populations, we also examined whether the joint effects of size and colour morph on detection could explain evolutionary dynamics in the wild. Morph frequency differences between sexes were largely in accordance with expectations from the results of the detection experiment. The results of the present study demonstrate that body size and colour morph can interactively influence detection of camouflaged prey. This may contribute to the morph frequency differences between male and female pygmy grasshoppers in the wild. Such interactive effects may also influence the dynamics of colour polymorphisms, and contribute to the evolution of ontogenetic colour change and sexual dichromatism. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 112–122.     

Dynamic sexual dichromatism in an explosively breeding Neotropical toad

Sexual selection often promotes the evolution of elaborate colour signals in males, but the importance of sexually selected colour signals remains poorly studied in amphibians. We used reflectance spectrometry to document pronounced sexual dichromatism and dramatic colour change in Bufo luetkenii, a toad that breeds in large aggregations at the onset of the rainy season in Costa Rica. Our observations suggest that males fade rapidly from a vibrant lemon yellow to a dull brown once they have paired with a female. We demonstrate this by showing that males are much brighter than females and that unpaired males are more colourful than males in amplexus. We also show that coloration fades rapidly when males are briefly held captive. This is, to our knowledge, the first study to document such dynamic change in male coloration and sexual dichromatism in anurans.     

Die Nachzucht des Roten Felsenhahns, Rupicola peruviana (Latham, 1790) und des Schildschmuckvogels, Querula purpurata (Müller, 1776) im Zoologischen Garten Wuppertal

Incubation, handrearing and motherrearing of 5 male Andean Cocks of the Rock (Rupicola peruviana) in Wuppertal Zoo is described, in particular the development of the juvenile plumage to adulthood, and the change of colour of the beak and the iris of the eye. Incubation lasted 26-28 days. The mother-reared nestling fledged after 28 days. The young male Cock of the Rock attained full adult plumage at the age of 18 months, not at 3 years as Del Hoyo et al. (2004) describe from free-living Cocks of the Rock. A report on the supposed world's first breeding of the Purple-throated Fruitcrow (Querula purpurata) is given. The incubation period was 25 days.     

Observations on the physiology and phylogeny of colour change in marine and freshwater leeches (Annelida: Hirudinea)

An investigation of some factors which influence physiological colour changes in 16 species of freshwater and marine leeches, representing the four major families, was carried out. The emphasis was on the freshwater glossiphoniid Theromyzon tessulatum (O. F. Müller, 1774) and on the marine piscicolid Calliobdella carolinensis Sawyer & Chamberlain, 1972. The individual chromatophores were assessed using the Hogben & Slome (1931) chromatophore index. Light has a profound effect on colour change in some leeches. They darken in the light and lighten in the dark. Leeches do not adapt to background. Temperature plays only a minor role in the colour change process in leeches. Its effect may differ from species to species. The colour change response normally takes about 15–30 minutes or longer. A series of ligation and ventral nerve cord transection experiments, primarily on C. carolinensis, demonstrates that the nervous system is intimately involved in the colour change process in at least some leeches. Participation by the nervous system in the colour change response is probably via a neurohumoral mechanism. In the Hirudinea physiological colour change occurs only in certain species of the Piscicolidae and the Glossiphoniidae. Physiological colour change probably evolved de novo in the rhynchobdellid leeches.     

Whatever the weather: ambient temperature does not influence the proportion of males born in New Zealand

Background

The proportion of male births has been shown to be over 50% in temperate climates around the world. Given that fluctuations in ambient temperature have previously been shown to affect sex allocation in humans, we examined the hypothesis that ambient temperature predicts fluctuations in the proportion of male births in New Zealand.

Methodology/Principal Findings

We tested three main hypotheses using time series analyses. Firstly, we used historical annual data in New Zealand spanning 1876–2009 to test for a positive effect of ambient temperature on the proportion of male births. The proportion of males born ranged by 3.17%, from 0.504 to 0.520, but no significant relationship was observed between male birth rates and mean annual temperature in the concurrent or previous years. Secondly, we examined whether changes in annual ambient temperature were negatively related to the proportion of male stillbirths from 1929–2009 and whether the proportion of male stillbirths negatively affected the proportion of male live births. We found no evidence that fewer male stillbirths occurred during warmer concurrent or previous years, though a declining trend in the proportion of male stillbirths was observed throughout the data. Thirdly, we tested whether seasonal ambient temperatures, or deviations from those seasonal patterns, were positively related to the proportion of male births using monthly data from 1980–2009. Patterns of male and female births are seasonal, but very similar throughout the year, resulting in a non-seasonal proportion of male births. However, no cross correlations between proportion of male births and lags of temperature were significant.

Conclusions

Results showed, across all hypotheses under examination, that ambient temperatures were not related to the proportion of male births or the proportion of male stillbirths in New Zealand. While there is evidence that temperature may influence human sex allocation elsewhere, such effects of temperature are not universal.     

Activity areas and daily movements of an arboreal monitor lizard,Varanus tristis (Squamata: Varanidae) during the breeding season

During the breeding season, in the western Great Victoria Desert, Western Australia, male Varanus tristis move greater daily distances (186.5 m) than females (99.7 m) and have larger activity areas (40.3 ha vs 3.7 ha). V. tristis retreat predominantly to live and dead upright Eucalyptus gongylocarpa (marble gum) trees that have hollows in their trunks and limbs. There is no observable difference between males and females in their preferred habitat, but females are found more frequently in a lesser number of preferred retreats during the breeding season.