@article {58436, title = {Weapon allometry and phenotypic correlation in the New Zealand sheetweb spider Cambridgea plagiata}, journal = {Biological Journal of the Linnean Society}, volume = {126}, year = {2018}, pages = {349-359}, chapter = {349}, abstract = {

Sexual selection has repeatedly driven the evolution of exaggerated secondary sexual traits in male animals. When multiple traits are used in competitive contexts, producing or bearing one trait may be costly and come at the expense of other traits via trade-offs. Conversely, sexually selected traits may show positively correlated patterns of relative investment. Males of the sheetweb spider, Cambridgea plagiata, have exaggerated chelicerae and use their chelicerae and forelegs in male\–male contest behaviour. In the present study, we describe the linear scaling relationship of the chelicerae and forelegs of both males and females. Chelicerae length was positively allometric for males, but not for females, whereas fore-tibiae and fore-femora showed a slightly negative allometric relationship for both sexes. We found no evidence of a trade-off between the length of tibiae and femora with chelicerae length when comparing simple phenotypic correlations. Rather, the length of the tibia and femur, relative to body size, both increased when compared with relative chelicerae length, indicating that these traits might be under correlational selection. This suggests that larger chelicerae and forelegs are advantageous to males and that when resources are available, males will invest in both these traits.

}, doi = {10.1093/biolinnean/bly170}, author = {Josephine E. McCambridge and Christina J. Painting and Leilani A. Walker and Gregory I. Holwell} } @article {53069, title = {Rapid divergence of courtship song in the face of neutral genetic homogeneity in the cactophilic fly Drosophila buzzatii}, journal = {Biological Journal of the Linnean Society}, year = {2018}, month = {Jan-08-2019}, abstract = {

A wide spectrum of song complexity has been documented in a broad range of animal taxa. However, the underlying processes shaping acoustic differences are still poorly understood. Empirical and theoretical studies suggest that different song parameters may be subject to different tempos and modes of evolution, resulting in a complex combination of stabilizing and directional selection that change among populations and through time. Nonetheless, the contribution of genetic drift to acoustic divergence is largely unexplored. In this study, we used the QST\–FST approach to investigate the relative role of selective and neutral processes in the evolution of courtship song in the cactophilic fly Drosophila buzzatii. We quantified variation in courtship song among 12 populations using flies reared under common-garden conditions. We found among-population divergence in courtship song parameters, but genetic homogeneity and no population structure. Using both mitochondrial DNA and microsatellite markers, we found evidence consistent with a role for directional selection causing song divergence. We discuss the statistical difficulties of detecting stabilizing selection as opposed to directional selection in our data. The role of song parameters in mate recognition and mate choice, and the role of sexual selection in song elaboration are also discussed.

}, keywords = {common-garden, divergent selection, microsatellites, mtDNA, QST{\textendash}FST}, issn = {0024-4066}, doi = {10.1093/biolinnean/bly108}, url = {https://academic.oup.com/biolinnean/advance-article/doi/10.1093/biolinnean/bly108/5073117}, author = {Iglesias, Patricia P and Soto, Ignacio M and Soto, Eduardo M and Calder{\'o}n, Luciano and Hurtado, Juan and Hasson, Esteban} } @article {52678, title = {Global song divergence in barn swallows (Hirundo rustica): exploring the roles of genetic, geographical and climatic distance in sympatry and allopatry}, journal = {Biological Journal of the Linnean Society}, year = {2018}, month = {Jul-03-2019}, abstract = {

Divergence in acoustic signals plays an important role in the production and maintenance of biodiversity in numerous taxa. In this study, we assess patterns of acoustic divergence in geographically isolated and sympatric subspecies of barn swallows (Hirundo rustica), including analyses of whether song differentiation varies with geographical isolation, genetic distance and climatic distance. We provide the first description of geographical variation in song among five of six currently recognized barn swallow subspecies. Temporal traits describing terminal trills were the most distinct song traits among subspecies, adding to growing evidence that trills are important in speciation among many birds, insects and fish. Across a ~6000 km transect of Russia, acoustic distance was predicted by genetic and geographical distance, but not climatic distance. We also found no reproductive character displacement of song traits in a contact zone between H. r. rustica and H. r. tytleri. Based on patterns discovered in this study, we infer an important role of sexual selection, genetic and/or cultural drift in the gradual build-up of acoustic divergence, which is accelerated in small populations.

}, issn = {0024-4066}, doi = {10.1093/biolinnean/bly012}, url = {https://academic.oup.com/biolinnean/advance-article/doi/10.1093/biolinnean/bly012/4943524}, author = {Wilkins, Matthew R and Scordato, Elizabeth S C and Semenov, Georgy A and Karaardi{\c C}, Hakan and Shizuka, Daizaburo and Rubtsov, Alexander and Pap, Peter L and Shen, Sheng-Feng and Safran, Rebecca J} } @article {52672, title = {Hornworm counterattacks: defensive strikes and sound production in response to invertebrate attackers}, journal = {Biological Journal of the Linnean Society}, volume = {123}, year = {2018}, month = {May-18-2018}, pages = {496 - 505}, abstract = {

Caterpillars (i.e. lepidopteran larvae) have evolved multiple defences against predators, with some large caterpillars showing aggressive defences (e.g. strikes and/or sound production). Although such behaviours can startle or warn vertebrate predators, defences against invertebrates remain unclear. We investigated the behavioural responses of the hornworm Langia zenzeroides (Lepidoptera: Sphingidae) against the invertebrate attacker Calosoma maximowiczi (Coleoptera: Carabidae). Fifth (last) instars of L. zenzeroides exhibited a striking response, in which the larva rapidly bent its head and thorax towards the body part stimulated by C. maximowiczi attacks. Strikes were also accompanied by opening of the mandibles, followed by sound production or regurgitation. In some cases, L. zenzeroides larvae caught the legs of C. maximowiczi and threw the beetles using their mandibles. Such counterattacks completely defended against attackers. The sounds that L. zenzeroides generated (pulse durations, 82\–314 ms; dominant frequencies, 5.0\–8.7 kHz; sound pressure level, 44.0\–56.9 dB SPL) were produced by forcing air through the eighth pair of abdominal spiracles. Our results indicate that hornworm larvae are able to deter predacious invertebrates using multiple defences.

}, issn = {0024-4066}, doi = {10.1093/biolinnean/blx156}, url = {https://academic.oup.com/biolinnean/article/123/3/496/4850692}, author = {Sugiura, Shinji and Takanashi, Takuma} }