Leader preference in Neoconocephalus ensiger katydids: a female preference for a nonheritable male trait

Abstract

Female preferences for males producing their calls just ahead of their neighbours, leader preferences, are common in acoustically communicating insects and anurans. While these preferences have been well studied, their evolutionary origins remain unclear. We tested whether females gain a fitness benefit by mating with leading males in Neoconocephalus ensiger katydids. We mated leading and following males with random females and measured the number and quality of F , the number of F and the heritability of the preferred male trait. We found that females mating with leaders and followers did not differ in the number of F or F offspring. Females mating with leading males had offspring that were in better condition than those mating with following males suggesting a benefit in the form of higher quality offspring. We found no evidence that the male trait, the production of leading calls, was heritable. This suggests that there is no genetic correlate for the production of leading calls and that the fitness benefit gained by females must be a direct benefit, potentially mediated by seminal proteins. The presence of benefits indicates that leader preference is adaptive in N. ensiger, which may explain the evolutionary origin of leader preference; further tests are required to determine whether fitness benefits can explain the phylogenetic distribution of leader preference in Neoconocephalus. The absence of heritability will prevent leader preference from becoming coupled with or exaggerating the male trait and prevent females from gaining a 'sexy-sons' benefit, weakening the overall selection for leader preference.

Imperfect synchrony in animal displays: why does it occur and what is the true role of leadership?

“…Studies of synchronous, acoustic-signalling taxa have examined proximate relationships between male quality and signal leadership by testing several indicators of male quality [13,14,16]. In Neoconocephalus katydids, leadership is highly repeatable, but is not heritable, and is unrelated to male morphology, fecundity or condition [13,15]. Similarly, in our study we found no direct link between male size with courtship effort and leadership (figure 2).…”

“…Our results show that leadership is linked to fast signalling rates (figure 3 e ). These are two courtship elements that are also correlated in synchronously signalling insects and anurans [14,15,16,40]. Leadership could, therefore, be costly for males in terms of higher energetic demands, meaning only males in good condition can produce leading waves.…”

“…This explanation only works if the signal is condition-dependent; males in good condition can honestly signal their quality to females by increasing signal intensity. However, empirical studies repeatedly fail to find clear evidence for this explanation [13][14][15][16], and whether signal leadership relates to male quality remains to be determined in many taxa.…”