Map showing known occurrences of five <i>Mecopoda</i> song types in India. [22].

<p>Map showing known occurrences of five <i>Mecopoda</i> song types in India. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0188843#pone.0188843.ref022" target="_blank">22</a>].</p

Stages of prey handling of giant cuttlefish (<i>Sepia apama</i>) by Indo-Pacific bottlenose dolphin (<i>Tursiops aduncus</i>).

<p>Prey: (a) flushed from algal cover to open substrate, b) pinned to substrate and killed; (c) lifted towards surface; (d) beaten with snout to release ink; (e) returned to substrate, inverted and forced along the sand to remove skin layer and release cuttlebone, (f) consumed whole.</p

Prey handling of giant cuttlefish (<i>Sepia apama</i>) by Indo-Pacific bottlenose dolphin (<i>Tursiops aduncus</i>).

<p>Prey: (a) pinned to substrate and killed; (b) lifted towards surface; (c) beaten with snout to release ink; (d) consumed whole.</p

Phonotactic response of <i>Mecopoda</i> Chirper females to Chirper calls played at chirp periods of 480 ms and 380 ms and Double Chirper calls played at chirp periods of 480 ms and 380 ms.

<p>Phonotactic response of <i>Mecopoda</i> Chirper females to Chirper calls played at chirp periods of 480 ms and 380 ms and Double Chirper calls played at chirp periods of 480 ms and 380 ms.</p

Additional file 1: Fig. S1-3. of Wild cricket social networks show stability across generations

Plots of the full (left box in each panel) and reduced (right box in each panel) simulations and their predictive distances (y axis). The predictive distance is the difference between the simulated values and the real value from the network. S1 is for mean path length, S2 for degree correlation and S3 for clustering coefficient. See Methods (in the main text) for details on how these were calculated and see Results for which comparisons are statistically significant. (ZIP 21 kb

Additional file 2: Table S1. of Wild cricket social networks show stability across generations

Characteristics of the cricket population and network statistics for each year. Isolated nodes are individuals that were not recorded to mate or fight another individual. Clustering is the ratio of complete triangles, where three crickets all interact with each other, to all possible triangles, including those where only two of the three crickets actually interact. Betweenness is the number of shortest paths between each pair of crickets in the network that pass through a particular cricket. We have taken the mean across all individuals, giving one measure of how well connected different parts of the network are (high values indicate poorly connected). Path length is the number of edges one must move along to connect any two nodes in a network. We have taken the mean, giving one value for how densely connected the network is (high values indicate low connectivity). (DOCX 16 kb

Phonotactic response by <i>Mecopoda</i> chirper females to the playback of calls from all <i>Mecopoda</i> song types.

<p>Phonotactic response by <i>Mecopoda</i> chirper females to the playback of calls from all <i>Mecopoda</i> song types.</p

Reproductive isolation in the acoustically divergent groups of tettigoniid, <i>Mecopoda elongata</i>

<div><p>Sympatric divergent populations of the same species provide an opportunity to study the evolution and maintenance of reproductive isolation. Male mating calls are important in sexual selection in acoustically communicating species, and they also have the potential to maintain isolation among species or incipient species. We studied divergent south Indian populations of the bush cricket <i>Mecopoda elongata</i> which are extremely difficult to distinguish morphologically, but which exhibit striking divergence in male acoustic signals. We performed phonotactic experiments investigating the relative preference of females of the “Chirper” song type for calls of all 5 of the song types found in the region (in varying degrees of sympatry). We found that Chirper females preferred their own song type and were completely unresponsive to three trilling song types. Chirper females were occasionally attracted to the call type “Double Chirper” (the call most similar to their own type), suggesting call preference alone cannot provide a complete isolating mechanism. To investigate the basis of call preference we investigated the response of chirper females to variation in chirp rate. Chirper females responded most frequently to a mean chirp rate characteristic of their own song type rather than a higher chirp rate which would be more characteristic of the Double-Chirper song type. This suggests females drive stabilising selection on male chirp rate, which may contribute to the maintenance of isolation. Finally, a no-choice mating experiment using Chirper females and Chirper and Double Chirper males revealed a significant preference of Chirper females to mate with their own song type, even without a requirement for phonotaxis. Overall, the strong specificity of Chirper females for their ‘own’ song type provides evidence for behavioural isolation among divergent sympatric <i>Mecopoda</i> song types being maintained by female preference for both male song type and subsequent mating probability driven by other cues.</p></div

Mate choice experiment using only lab-reared crickets.

<p>Generalised linear-mixed model analyses looking at the propensity of males to start singing, and the propensity of females to mount and mate within 10 minutes to con- and heterospecific partners. The experimental set-up between the mate choice tests differed slightly. In this experiment each individual was tested against both a hetero- and conspecific partner and we controlled for presentation order (see main text for details). The <i>G. campestris</i> used in this experiment were the F1-generation from wild-caught individuals and reared in the lab in 2009. The <i>G. bimaculatus</i> were raised in the lab for several generations. Explanatory variables retained in the final model are in bold.</p

Mate choice experiments.

<p>Males and females of the two species were paired in con- and heterospecific pairs and the proportion of males starting courtship song (<b>A</b>, <b>D</b>), females mounted (<b>B</b>, <b>E</b>) and mated after 10 minutes (<b>C</b>, <b>F</b>). The top row (<b>A</b>–<b>C</b>) represents trials using wild-caught <i>G. campestri</i>s (2009 and 2010) of unknown age and mating status. The captive bred offspring of the wild-caught <i>G. campestri</i>s (2009) were used in a subsequent mate choice experiment (<b>D</b>–<b>F</b>) in which e.g., rearing condition, mating status and mating sequence could be controlled for (see main text for more details). Lab-reared <i>G. bimaculatus</i> were used for all trials.</p