Female mating competition alters female mating preferences in common gobies

Abstract

Mating decisions can be affected by intrasexual competition and sensitive to operational sex-ratio (OSR) changes in the population. Conceptually, it is assumed that both male and female mate-competition may interfere with female reproductive decisions. Experimentally, however, the focus has been on the effect of male competition on mate choice. In many species with paternal care as in the common goby Pomatoschistus microps, the OSR is often female-biased and female mate-competition for access to available nesting males occurs. Using the same protocol for 3 experiments testing the effect of a perceived risk of female mate-competition, I studied female preferences for nest-holding males differing in its nest size (large/small), body size (large/small), and nest status (with/without eggs already in nest) and measured mating decisions, spawning latencies, and clutch size. Regardless of the social context, females preferred males with larger nests. A preference for large males was only expressed in presence of additional females. For nest status, there was a tendency for females to prefer mating with males with an empty nest. Here, female–female competition increased the propensity to mate. The results of this study show that females are sensitive to a female competitive social environment and suggest that in choice situations, females respond to the social context mainly by mating decisions per se rather than by adjusting the clutch size or spawning latency. Females base their mating decisions not only on a male’s nest size but also on male size as an additional cue of mate quality in the presence of additional females.

Male and female preferences for nest characteristics under paternal care

“…Our current study again reveals a strong correlation between male body weight and female preference. Large males are known to be preferred in particular under perceived risks of female–female competition (Heubel, ) or a chance of male–male competition (Lehtonen & Lindström, ), with the latter scenario nicely matching our experimental choice setup.…”

“…These scores estimate the volume of additional sand a male should add to the wide–low nest model to cover a proportion of the entrance or nest roof: 0 = 0%, 1 = 1%–25%, 2 = 26%–50%, 3 = 51%–75%, 4 = 76%–100% (Figure ). At this time point, nest occupation is usually settled (Heubel, ; Magnhagen, ) and we further assessed and defined the currently occupied nest as a male's choice in this first experimental trial, with N = 142 males exhibiting nest choice.…”

“…Indeed, females have been shown to rely on different cues when environmental conditions vary (Chaine & Lyon, 2008;de Jong, Amorim, Fonseca, & Heubel, 2018). Similarly, the relevance of (more indirect) nest cues versus (more direct) male phenotype cues has varied between studies (Head, Fox, & Barber, 2017;Heubel, 2018). Many earlier studies investigating the role of alternative cues in mate choice face the challenge to clearly isolate the preference for nest quality from preference for male phenotypes, and none has independently controlled multiple nest traits when studying female choice (but see Bose et al, 2018).…”

“…Paternal care includes water ventilation by fanning with pectoral fins, as well as actively protecting the clutch from predators (Jones & Reynolds, 1999b), and removal of dead or infected eggs within the brood (Vallon, Anthes, & Heubel, 2016). Females have a preference for males with larger nests, but unlike in many other species with male parental care (Forsgren, Kvarnemo, & Lindström, 1996;Kraak & Groothuis, 1994;Requena & Machado, 2015), females do not always prefer nests that already contain eggs (Heubel, 2018, but see Reynolds & Jones, 1999. Offspring survival also varies with nest characteristics: A well-constructed nest in terms of concealing sand cover and narrow entrance is less susceptible to predation from both the sand level (Jones & Reynolds, 1999b) and aerial predation (Lindström & Ranta, 1992).…”

“…Female gobies apparently discriminate among potential partners based on multiple cues such as nest size and male body size (Heubel, 2018;Lehtonen, Rintakoski, & Lindström, 2007). However, the importance of nest modifications beyond the size of the nest per se remains unclear.…”