RESEARCH PAPER: Multiple Sexual Ornamentation Signals Male Quality and Predicts Female Preference in Minnows

Abstract

Sexual ornamentation often consists of multiple components. Different sexual signals may indicate different aspects of mate quality or reflect quality in different time scales. On the other hand, same signals can have a dual function and are used both in male–male competition and courtship. Many fish species are capable of rapidly altering their colouration (ephemeral colour changes), but this capability is usually ignored in sexual selection studies. Here, we used experimentally manipulated social environments to study the ephemeral colour changes in multicomponent sexual signals of male minnows (Phoxinus phoxinus) during male–male competition and female choice. We found that the dominant males courted the females more actively and had redder and/or darker skin colouration than the subordinate males. Furthermore, darkness difference between subordinate and dominant males increased in the presence of female, which suggests that the male–male competition may increase the honesty of signalling and thus facilitate female choice. In support of this hypothesis, females had a strong behavioural preference towards the more colourful males, which may indicate female choice. As colourful males often had a higher social status than paler individuals, it is possible that females base their preference on male status, not only the colouration per se. In any case, our results suggest that sexual ornamentation of male minnows may signal status, courting activity and superior quality of the males and that these signals may have a dual function in both male–male competition and female choice. Females preferred different ornamental traits (dark and red colour patterns) relatively equally, indicating that mate choice is based on multiple cues.

Female mate choice for multimodal courtship and the importance of the signaling background for selection on male ornamentation

“…However, not all traits deemed to be ornaments have been found to play a vital role in female mate choice (Saether et al, 2000;Westneat, 2006;Takahashi et al, 2008;Shamble et al, 2009), causing researchers to re-evaluate the putative function of such secondary sexual traits. In lieu of an explanation requiring direct selection on male ornaments, increased support is surfacing for hypotheses suggesting that female mate choice is based upon combinations of traits or signal interactions (Kekäläinen et al, 2010;Grafe et al, 2012;Taylor et al, 2011) and/or upon motor performance, with ornamentation evolving secondarily in an enhancing role (see Byers et al, 2010;Barske et al, 2011;Hebets et al, 2011;Wilgers and Hebets, 2012). The former hypothesis proposes that separate signal components interact in various ways, dependent on signaling system, to alter female response.…”

“…Female mate choice has since been shown to exhibit strong selection pressure on male ornaments (e.g. Hamilton and Zuk, 1982;Hill, 1991;Andersson, 1994;Wilkinson and Reillo, 1994) and investigating how secondary sexual characters influence mating success continues to be a focus for evolutionary biologists (de Heij et al, 2011;Karino et al, 2011;Rick et al, 2011;Kekäläinen et al, 2010;Toomey and McGraw, 2012). However, not all traits deemed to be ornaments have been found to play a vital role in female mate choice (Saether et al, 2000;Westneat, 2006;Takahashi et al, 2008;Shamble et al, 2009), causing researchers to re-evaluate the putative function of such secondary sexual traits.…”

Full Issue

“…This hypothesis has been suggested for other species as well. A positive correlation between signal honesty and female proximity has been shown for running agility in the pronghorn (Antilocapra americana; Byers 1997), complexity of calls in the tungara frog (Physalaemus pustulosus, Akre and Ryan 2011), color darkness in common minnows (Phoxinus phoxinus; Kekäläinen et al 2010), and carotenoid-based bill color in Zebra Finches (Gautier et al 2008).…”

Sex and Sexual Ornamentation Associated with Survival of the Cyprinid Fish, Rutilus rutilus, under Disease Stress

“…Therefore, the present result of higher survival in high-ornamented males is in accordance with the hypothesis of parasite-mediated sexual selection [5] predicting that males would signal resistance by their sexual ornaments. This resistance may be heritable, since, for example, in the whitefish, the parental breeding tubercle ornamentation has been found to indicate offspring survival [27] and offspring performance [6].…”