Can females choose to avoid mating failure in the seed bug Lygaeus simulans?

E.V (Ginny) Greenway,Vicki L Balfour,David M Shuker

doi:10.1016/j.anbehav.2017.05.004

E.V (Ginny) Greenway, Vicki L Balfour + Show 1 more

Open Access

https://doi.org/10.1016/j.anbehav.2017.05.004

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Abstract

It is becoming increasingly clear that copulation does not necessarily always lead to offspring production in many organisms, despite fertilization success presumably being under both strong natural and sexual selection. In the seed bug Lygaeus simulans, between 40% and 60% of copulations fail to produce offspring, with this ‘mating failure’ representing a significantly repeatable male-associated trait. Mating has been demonstrated to be costly in this species and, as such, we might expect females to minimize the chance of mating failure by displaying a preference for males with higher insemination success where possible. After assaying males for mating failure, we asked whether females preferred males with a history of successful inseminations versus unsuccessful inseminations in pairwise mate choice trials. Contrary to our expectations, females showed no preference for more successful over less successful males. Moreover, females showed no preference for larger males in the choice trials, even though larger males were significantly more likely to successfully inseminate females in the initial assay. This apparent lack of female precopulatory choice suggests that postcopulatory choice mechanisms may be key to mating failure in this species. However, this does not necessarily explain why females pay the cost of mating with males they will then reject via postcopulatory processes. More generally, our results suggest that mating failure may play a largely underappreciated role in mating systems evolution, influencing both the cost of choosiness, and the costs and benefits of polyandry.

Highlights

It is becoming increasingly clear that copulation does not necessarily always lead to offspring production in many organisms, despite fertilization success presumably being under both strong natural and sexual selection
After assaying males for mating failure, we asked whether females preferred males with a history of successful inseminations versus unsuccessful inseminations in pairwise mate choice trials
Despite the fact that functional fertility itself is often not apparent until mating is underway or over, precopulatory mate choice favouring fertile individuals of both sexes has been documented in some species, perhaps most explicitly in the parasitoid wasp Nasonia vitripennis

Summary

METHODS

Lygaeus simulans is an aposematic species of seed predator, with a European-wide distribution, frequently co-occurring with its sister species L. equestris (Solbreck, Olsson, Anderson, & Fo€rare, 1989). The spermatheca was removed from each female and placed on a glass slide under a coverslip with a drop of saline solution It was examined and scored for the presence or absence of sperm under 400Â magnification using a light microscope, blind to the mating outcome. To assess whether sperm transfer had occurred, the spermatheca was placed on a slide under a coverslip and viewed at higher magnification under a light microscope to check for the presence of sperm, which forms visible strands (Micholitsch et al, 2000) In this individual, a female taken from our stock population, the spermathecal duct contains a fragment (f) of the male intromittent organ, which has presumably broken off during copulation. All statistical analyses were carried out in R v.3.0.2 (R Core Team, 2013)

RESULTS

Findings

DISCUSSION