Sexual selection and organs of sense: Darwin’s neglected insight

Abstract

Studies of sexual selection that occurs prior to mating have focussed on either the role of armaments in intra-sexual selection, or extravagant signals for inter-sexual selection. However, Darwin suggested that sexual selection may also act on ‘organs of sense’, an idea that seems to have been largely overlooked. Here, we refine this idea in the context of the release of sex pheromones by female insects: females that lower the release of sex pheromones may benefit by mating with high-quality males, if their signalling investment results in sexual selection favouring males with larger or more sensitive antennae that are costly to develop and maintain.

Evolution of male antennal size in moths (Lepidoptera): a comparative test of potential trade‐offs and correlated growth in Australian species

“…By contrast with this research on ornaments and weaponry, there has been much less focus on sensory traits (Elgar et al . ), and very few have looked at the associations in a comparative cross‐species context. One exception is the recent study of firefly species by Stanger‐Hall et al .…”

“…Consequently, he argued, sexual selection may act on 'organs of sense', such as insect antennae. While a large amount of research has focussed on the evolution of sexually selected traits such as ornaments or weaponry, there has been very little research on this neglected aspect of Darwin's sexual selection theory (see recent review by Elgar et al 2019).…”

“…By contrast with this research on ornaments and weaponry, there has been much less focus on sensory traits (Elgar et al 2019), and very few have looked at the associations in a comparative cross-species context. One exception is the recent study of firefly species by Stanger-Hall et al (2018), which found that nocturnal species tend to have shorter antennae but larger eye size, presumably because such species tend to use photic signals to attract and locate mates.…”

The size of signal detection and emission organs in a synchronous firefly: sexual dimorphism, allometry and assortative mating

“…The morphology, physiology and behavior of signal detection and emission organs are frequently influenced by selective pressures not related to the sexual communication function (Niven & Laughlin, 2008;Stöckl et al, 2013;Elgar, Johnson & Symonds, 2019). Thus, another possible explanation for our results is the existence of additional selective pressures acting in opposite direction to sexual selection or in a more complex way.…”

Oviposition preferences and antennal size in carrion flies

“…Adult female insects detect appropriate oviposition and feeding sites using chemical cues (e.g., Bernays & Chapman, 1994; Wäschke et al, 2013; Webster & Cardé, 2017) that are typically detected by receptors located on sensilla, which are supported by the antennae (Elgar et al, 2018). The evolutionary significance of the remarkable inter‐specific variation in the size, shape, and micro‐morphology of insect antennae is surprisingly poorly understood (Schneider, 1964; Chapman, 1982; Bau & Cardé, 2015; Elgar et al, 2018, 2019). Nevertheless, emerging evidence suggests that insect antennal micro‐morphology responds to selection exerted by both the nature of the odour, including volatility and complexity, and the context of odour detection, such as foraging, oviposition, mate searching, and social organization (Elgar et al, 2018).…”