Can behaviour impede evolution? persistence of singing effort after morphological song loss in crickets
Rayner, Jack; Schneider, Will; Bailey, Nathan (2020), Can behaviour impede evolution? persistence of singing effort after morphological song loss in crickets, Dryad, Dataset, https://doi.org/10.5061/dryad.g79cnp5m8
Evolutionary loss of sexual signals is widespread. Examining the consequences for behaviours associated with such signals can provide insight into factors promoting or inhibiting trait loss. We tested whether a behavioural component of a sexual trait, male calling effort, has been evolutionary reduced in silent populations of Hawaiian field crickets (Teleogryllus oceanicus). Cricket song requires energetically costly wing movements, but ‘flatwing’ males have feminised wings that preclude song and protect against a lethal, eavesdropping parasitoid. Flatwing males express wing movement patterns associated with singing but, in contrast to normal-wing males, sustained periods of wing movement cannot confer sexual selection benefits and should be subject to strong negative selection. We developed an automated technique to quantify how long males spend expressing wing movements associated with song. We compared calling effort among populations of Hawaiian crickets with differing proportions of silent males, and between male morphs. Contrary to expectation, silent populations invested as much in calling effort as non-silent populations. Additionally, flatwing and normal-wing males did not differ in calling effort. The lack of evolved behavioural adjustment following morphological change in silent Hawaiian crickets illustrates how behaviour might sometimes impede, rather than facilitate, evolution.
Sining effort data was produced by automatic video tracking of adult male crickets with reflectors on their wings. The csv files were produced by MATLAB using custom scripts. Two files are provided, clearly labelled: one in which singing bouts are defined by 10-second intervals, the other by 5-second intervals. The variable canSing refers to whether each individual was able to sing, and 'pl' refers to pronotum length in mm.
Natural Environment Research Council, Award: NE/L011255/1