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Acoustic communication in animals relies upon specific contexts and environments for effective signal transmission. Increasing anthropogenic noise pollution and different weather conditions can disrupt acoustic communication. In this study, we investigated call parameter differences in the bladder grasshopper Bullacris unicolor inhabiting two sites in close proximity to each other that differed in their noise levels. Calling activity was monitored via passive acoustic recorders. Weather conditions, including wind speed, temperature and humidity, were also recorded. We found that the interval between successive calls increased with higher noise levels at both sites, and the peak frequency became lower. The total number of calls detected also decreased with anthropogenic noise, but this relationship was only evident at the noisier site. In addition, grasshoppers shifted the timing of their calls to later in the night at the noisier site, possibly to take advantage of relatively lower noise levels. We also found that weather conditions, particularly temperature, had a significant influence on call parameters. Further studies are thus needed to disentangle the effects of anthropogenic noise and environmental variables on calling activity in this species. Our results lend support to the growing concern regarding the effects of noise pollution on animal acoustic signalling systems and also highlight the complexity of factors which affect sound signalling in natural environments.

Guppies (Poecilia reticulata) are widely used as a model species in mate choice studies. Although native to South America, guppies have been introduced to natural water bodies in disparate regions of the globe. Here, for the first time, we examine guppies from one such introduced population in Japan where males have evolved a predominantly blue color pattern. Previous studies of wild-type guppies have shown blue to play a relatively minor role in the mate choice decisions of females compared to other traits, such as orange, and the importance of blue is not universally supported by all studies. The Japanese population therefore presents an ideal opportunity to re-examine the potential significance of blue as a mate choice cue in guppies. Mate choice experiments, in which female Japan blue guppies were given a choice between pairs of males that differed in their area of blue coloration but were matched for other traits, revealed that females prefer males with proportionately larger amounts of blue in their color patterns. We discuss possible factors, including sexual and ecological selection, which may have led to the evolution of unusually large areas of blue at the expense of other colors in Japan blue guppies. However, further studies are needed to distinguish between these scenarios. IntroductionGuppies (Poecilia reticulata) are small and brightly colored fish native to South America and islands of the Caribbean. The color patterns of wild-type males are highly polymorphic and vary widely among populations, but generally consist of a combination of carotenoid (red, orange, and yellow) and melanin (black) pigments, that absorb certain wavelengths of light, and iridescent (blue, green, violet, and white) structural colors that scatter and reflect certain wavelengths (Bagnara et al. 2007;Price et al. 2008). These elements differ in size, position, shape, and intensity (Houde 1997). Numerous studies have demonstrated the significance of male color patterns to female mating preferences in both natural (Houde 1987;Houde and Endler 1990;Kodric-Brown 1993; Evans et al. 2004) and introduced (Brooks and Caithness 1995; Brooks and Endler 2001;Karino and Shinjo 2004) populations of guppies. In particular, these studies have provided overwhelming evidence in support of the role of size and saturation of carotenoid patches as major targets of mate choice (e.g., Houde 1987; Kodric-Brown 1989;Long and Houde 1989;Houde and Endler 1990), although the relative strength of this preference for orange does vary extensively among individuals (Kodric-Brown and Nicoletto 1996) and populations

There are several factors, such as genetic drift, gene flow and migration that affect the population genetic structure and phylogeographic distribution of genetic lineages within single species. Previous studies of the bladder grasshoppers, Bullacris unicolor of South Africa, showed divergence in mitochondrial CO1 (cytochrome c oxidase subunit 1) haplotype diversity and significant genetic structure. In this study, we revisit these findings adding more samples from different locations and using mitochondrial CO1 and Internal transcribed spacer (ITS) gene sequences. We tested the hypothesis that the western, northern and eastern distribution ranges of B. unicolor show different population genetic patterns, corresponding with isolation-by-distance. Mitochondrial CO1 and ITS data were collected for 99 individuals from 12 localities across the Western, Northern and Eastern sides of South Africa. Overall, significant variation in genetic structure was found across the localities as indicated by F ST analyses. Haplotype and phylogeographical analyses suggested that restricted gene flow played a role in shaping current genetic patterns, although isolation-by-distance was not supported, as confirmed by Mantel tests. Phylogenetic trees of both genetic sequences revealed two major clades, with western and northern sides. Also, the major clades exhibit a few sub-clades within the localities, showing other factors shaping the genetic structure of B. unicolor include the geographical barriers, and most likely due to changes in habitat specificity and habitat fragmentation. Taken together, this study aims to contribute information on the population structure and genetic diversity of B. unicolor populations across South Africa.

Host-associated genetic differentiation in grasshoppers has received limited attention, due to a lack of information on grasshopper-plant associations. The bladder grasshopper, Bullacris unicolor (Linnaeus, 1758) (Orthoptera: Pneumoridae), is a phytophagous species that can occur on at least six host plants within its geographic range. However, the relationship between host plant association and genetic variation of bladder grasshoppers has not been studied before. In light of this, the present study examined host plant-related genetic [mitochondrial cytochrome oxidase 1 (CO1) and the internal transcribed spacer (ITS) gene regions] and morphological (antennal length, body length, head width, abdomen width, femur length, tibia length and pronotum length) divergence within a population of B. unicolor. We used two plant species, belonging to different families, namely Didelta spinosa (L.fil.) Aiton (Asteraceae) and Roepera morgsana (L.) Beier & Thulin (Zygophyllaceae), to evaluate variation between individuals collected on these two sympatric host plants at a single locality in the Northern Cape, South Africa. The results demonstrated non-significant host related genetic variation with very low values of FST, indicating a low level of variation. The phylogram strongly indicated that there are no host-associated genetic differences in B. unicolor by displaying limited genomic clustering, whereas some differentiation was observed between the morphological measurements of males and females among host plants. Further studies using microsatellite molecular markers may help to discern population genetic structure. In addition, significant host-associated morphological divergence highlights the need to examine the mechanisms by which host utilization affects morphological features.