Serial monogamy benefits both sexes in the biparental convict cichlid

Abstract

Monogamy can be either long-term or serial, with new pairs formed with each breeding bout. Costs and benefits are associated with each strategy. Because biparental convict cichlids (Amatitlania nigrofasciata) typically switch mates, exhibiting serial monogamy, we tested for the costs associated with forcing individuals to remain with the same mate. Convict cichlids were observed over two successive breeding bouts, either with the same or a new, equally experienced, mate. Parental behavior did not differ between breeding bouts, nor did brood size. Surprisingly, fish that remained with their original partner for a second bout took significantly longer to produce a brood compared to fish that paired with new partners. New partners were also more likely to successfully produce a second brood than re-mated partners. This is in contrast to the majority of bird studies that show many benefits to staying with the same partner for multiple broods. In convict cichlids, there seems to be no benefit associated with remaining with the same partner and switching mates reduces duration between broods for both males and females, potentially increasing overall reproductive success.

Figure 4: Time that the pair spent together engaged in defense against a conspecific intruder (percent of total time observed) during the first and second breeding bouts.

“…Specifically, with successive breeding bouts, females spent increasingly more time in the nest while males focused more on aggressive behaviors. Unlike Colgan & Salmon (1986), our previous study (Snekser & Itzkowitz, 2019) did not indicate an increase in brood size nor any overall parental behavioral differences across breeding bouts. Across both studies, there were very few meaningful differences in behavior when comparing parents that paired with the same versus a new partner (Colgan & Salmon, 1986;Snekser & Itzkowitz, 2019).…”

“…Unlike Colgan & Salmon (1986), our previous study (Snekser & Itzkowitz, 2019) did not indicate an increase in brood size nor any overall parental behavioral differences across breeding bouts. Across both studies, there were very few meaningful differences in behavior when comparing parents that paired with the same versus a new partner (Colgan & Salmon, 1986;Snekser & Itzkowitz, 2019). This is in contrast to studies of avian species, in which mate fidelity has repeatedly been shown to increase reproductive success (e.g., Hatch & Westneat, 2007;Leach et al, 2020), decrease time between broods (e.g., Lifjeld & Slagsvold, 1988), increase adult survivorship (Leach et al, 2020), and strengthen coordination within pairs (e.g., Choudhury, 1995;Ihle, Kempenaers & Forstmeier, 2015).…”

“…Little evidence exists to support the hypothesis that behavioral consistency of parents also enhances offspring survival in this fish, as it does in birds (Bradley et al, 1990;Dubois & Cézilly, 2002;Adkins-Regan & Tomaszycki, 2007). Previous studies with the convict cichlid indicate that mate fidelity has little influence on offspring survival (Colgan & Salmon, 1986) and on brood size (Colgan & Salmon, 1986;Snekser & Itzkowitz, 2019). Perhaps consistency in parental behavior exists in convict cichlids but the lack of increased reproductive success commonly associated with mate fidelity results in little evolutionary benefit to remaining with the same partner.…”

“…A closer look at this measure reveals that pairs that remained together seemed to be (on average) slower at retrieving young in the second bout. Pairs comprised of new partners were generally faster during the second bout (though no significant difference was found between the groups; Snekser & Itzkowitz, 2019). This decrease/increase in the behavior from bout to bout would explain the lack of absolute consistency for time spent retrieving.…”

Convict cichlid parents that stay with the same mate develop unique and consistent divisions of roles

“…This study is the second part of a study that tested if pairs that successfully raised offspring were more likely to form a pair bond and raise offspring compared to individuals that had not previously raised a brood together. The results were clear: there was no benefit in producing a second clutch of offspring with the same partner as compared to mating with a new partner ( Snekser & Itzkowitz, 2019 ). These results are valuable because they allow us to ask if pairs with familiar partners are behaving differently from pairs that have not previously bred with each other, in spite of both groups having similar reproductive success.…”