Will male advertisement be a reliable indicator of paternal care, if offspring survival depends on male care?

Abstract

Existing theory predicts that male signalling can be an unreliable indicator of paternal care, but assumes that males with high levels of mating success can have high current reproductive success, without providing any parental care. As a result, this theory does not hold for the many species where offspring survival depends on male parental care. We modelled male allocation of resources between advertisement and care for species with male care where males vary in quality, and the effect of care and advertisement on male fitness is multiplicative rather than additive. Our model predicts that males will allocate proportionally more of their resources to whichever trait (advertisement or paternal care) is more fitness limiting. In contrast to previous theory, we find that male advertisement is always a reliable indicator of paternal care and male phenotypic quality (e.g. males with higher levels of advertisement never allocate less to care than males with lower levels of advertisement). Our model shows that the predicted pattern of male allocation and the reliability of male signalling depend very strongly on whether paternal care is assumed to be necessary for offspring survival and how male care affects offspring survival and male fitness.

Does a trade‐off between current reproductive success and survival affect the honesty of male signalling in species with male parental care?

“…The predictions of our previous model for male allocation of resources (Kelly & Alonzo, 2009) differed substantially from those of earlier theory which predicted that male signalling can be an unreliable indicator of male parental care (Kokko, 1998) and from empirical observations based on that theory (Candolin, 1999; Duckworth et al. , 2003).…”

“…, 1993). However, more recent theoretical work (Kokko, 1998; Kelly & Alonzo, 2009) has shown that in species where the costs of providing the direct benefit are high, males may produce less exaggerated signals, but that the ability of a male to produce any signal at all can itself act as a reliable indicator of male quality for females.…”

Exclusive Male Egg Care and Determinants of Brooding Success in a Millipede

“…Females may prefer males with wider body segments because they provide larger direct benefits to the female; e.g. better performance with regard to parental care (Hoelzer 1989; Kokko 1998; Kelly & Alonzo 2009). If the primary function of paternal care in B. nodulosa is to protect eggs from fungal infection, then it is likely that the protective ability is related to male body size (width) and the capacity to cover and manipulate the egg mass surface.…”

“…In addition to offspring survival, male care behaviour may enhance reproductive success through increased mating opportunities, because it provides direct benefits to mates and thus attracts them (Tallamy 2000). Males of species with established paternal care can advertise their parental intent to females (Hoelzer 1989; Kokko 1998; Kelly & Alonzo 2009); and the males may develop sexual traits reflecting their parental qualities and thereby enjoy higher mating success. Through such processes mediated by parental care, male reproductive success in the field can be affected by a variety of phenotypic and social or environmental factors.…”

The sexual selection paradigm: have we overlooked other mechanisms in the evolution of male ornaments?

“…Male ornaments can then function as badges of status that allow males to resolve conflicts without resorting to costly fights, which in turn can improve current or future reproductive success [7][8][9]. Second, ornaments could be adopted as indicators of mate quality in mate choice, or of competitive ability in the competition for females, and be favoured by sexual selection for improved mating and fertilization success [10,11]. Yet teasing apart the relative importance of sexual and social selection in driving the evolution of the ornaments can be difficult [12].…”