Male genital titillators and the intensity of post-copulatory sexual selection across bushcrickets

Animal genitalia are diverse and a growing body of evidence suggests that they evolve rapidly under post-copulatory sexual selection. This process is predicted to be more intense in polyandrous species, although there have been very few comparative studies of the relationship between the complexity of genital structures in males and measures of the degree of polyandry. In some bushcricket families, males possess sclerotised copulatory structures known as titillators, which are inserted into the female’s genital chamber and moved rhythmically. Like other genital structures, bushcricket titillators are widely used as important taxonomic characters and show considerable variation across species in structure, shape and the extent to which they are spined. Here, we examine relationships between the presence/absence of titillators, titillator complexity and both mating frequency and the degree of polyandry in bushcrickets, using phylogenetic comparative analyses. Using published sources combined with original observations, data were obtained for the mean level of polyandry, the duration of the male and female sexual refractory periods and the level of complexity of titillators. To analyse data, we fitted phylogenetic generalised least squares models. No significant relationships were found between titillator presence or complexity and either the level of polyandry, duration of the male’s sexual refractory period or the ratio of the female and male sexual refractory periods. The duration of the female’s refractory period, however, was positively associated with titillator presence and negatively associated with titillator complexity. The data therefore partially support the hypothesis that post-copulatory sexual selection drives genital evolution in this taxon

Development, reproductive capacity and diet of the Mediterranean grasshopper Arcyptera brevipennis vicheti Harz 1975 (Orthoptera: Caelifera: Acrididae: Gomphocerinae)

Arcyptera brevipennis vicheti Harz 1975 (Orthoptera: Acrididae) is a rare grasshopper native to Mediterranean grassland habitats in the Languedoc-Roussillon region of southern France. Changes in land-use have modified these unique habitats, thus threatening the survival of A. b. vicheti populations. To improve the conservation of this species this study aimed to describe important aspects of its biology and ecology. Development of nymphs passed through five instars after hatching and was closely associated with the Mediterranean spring season. A prominent sexual size dimorphism is highlighted, but the larger females developed in the same number of instars as males. Hind femur length and number of antenna segments were useful characters when distinguishing between nymphal instars. All individuals were brachypterous, indicating that A. b. vicheti is unable to fly. Adult females laid 15 eggs on average and deposited no more than two egg pods in their lifetime. Grass debris made up 93% of faecal content of both sexes. Our results provide valuable information for the conservation of this highly endangered grasshopper species.Peer reviewe

Development, reproductive capacity and diet of the Mediterranean grasshopper Arcyptera brevipennis vicheti Harz 1975 (Orthoptera: Caelifera: Acrididae: Gomphocerinae)

Arcyptera brevipennis vicheti Harz 1975 (Orthoptera: Acrididae) is a rare grasshopper native to Mediterranean grassland habitats in the Languedoc-Roussillon region of southern France. Changes in land-use have modified these unique habitats, thus threatening the survival of A. b. vicheti populations. To improve the conservation of this species this study aimed to describe important aspects of its biology and ecology. Development of nymphs passed through five instars after hatching and was closely associated with the Mediterranean spring season. A prominent sexual size dimorphism is highlighted, but the larger females developed in the same number of instars as males. Hind femur length and number of antenna segments were useful characters when distinguishing between nymphal instars. All individuals were brachypterous, indicating that A. b. vicheti is unable to fly. Adult females laid 15 eggs on average and deposited no more than two egg pods in their lifetime. Grass debris made up 93% of faecal content of both sexes. Our results provide valuable information for the conservation of this highly endangered grasshopper species.Peer reviewe

Figure 1 from: Lehmann AW, Devriese H, Tumbrinck T, Skejo J, Lehmann GUC, Axel Hochkirch A (2017) The importance of validated alpha taxonomy for phylogenetic and DNA barcoding studies: a comment on species identification of pygmy grasshoppers (Orthoptera, Tetrigidae). ZooKeys 679: 139-144. https://doi.org/10.3897/zookeys.679.12507

In a recently published paper on colour polymorphism in a Pygmy grasshopper from China (Zhao et al 2016) an unidentified Paratettix sp. was misidentified as Tetrix bolivari. This case highlights the need for correct species identification and provides an opportunity to recommend some aspects of Good Taxonomic Practice (GTP) in Tetrigidae to reduce the number of erroneous identifications

Adaptive plasticity of bushcricket acoustic signalling in socially heterogeneous choruses

Anichini M, Rebrina F, Reinhold K, Lehmann GUC. Adaptive plasticity of bushcricket acoustic signalling in socially heterogeneous choruses. ANIMAL BEHAVIOUR. 2019;158:139-148.In many species, males produce sounds to attract a female. In a chorus, males actively adjust their acoustic production depending on the presence and number of mating rivals. Plasticity in signal features might then be advantageous as males could tune their signalling activity to the contest intensity. However, the ability to exhibit plastic behaviour might be constrained and interindividual variation in plasticity can occur. In this field study, we examined the influence of body mass and social environment on the signal expression of male bushcrickets, Poecilimon veluchianus veluchianus. We tested whether differences in signal features of rivals of different body mass and number led to changes in the competition pressure perceived by focal males and, consequently, in their acoustic responses. We used the first principal component from a principal component analysis, reflecting verse duration, duty cycle and syllable number, as a measure of acoustic output. We found that the rivals' acoustic output depended only on their number, being higher for two rivals than one. However, the response of heavy focal males depended on the rivals' body mass. Contrary to what we expected, heavy males produced shorter verses with fewer syllables when competing against two heavy rivals than when competing against one or two light rivals or one heavy rival. Facing light competitors, heavy focal males responded more to two rivals than to one. In contrast, light focal males did not vary their signal features depending on competition conditions. These results indicate that body mass and social context drive interindividual variation in the capacity of P. v. veluchianus males to adjust their signal features to competition levels. We compare these findings with those previously obtained on congeneric species and discuss the outcomes' similarities and discrepancies. Lastly, we provide suggestions for future studies of socially induced plasticity in sexually selected acoustic signal features. (C) 2019 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved

Correction to: The role of hybridisation in the origin and evolutionary persistence of vertebrate parthenogens: a case study of Darevskia lizards.

An amendment to this paper has been published and can be accessed via a link at the top of the paper