Parental Roles and the Amount of Care In a Bi-Parental Substrate Brooding Cichlid: The Effect of Size Differences Within Pairs

Abstract

SummaryParental roles and the amount of care in bi-parental fish have been assumed to be determined by sex. We studied the parental behaviour in a substrate brooding cichlid Julidochromis ornatus (40-90 mm in total length) in which both parents participate in care of eggs and young. In the study population, ca 80% of paired females were larger than their partners and pairs mated assortatively for size. Males spent more time with their offspring in female-largest pairs, whereas the opposite was found for male-largest pairs. These differences in the amount of care were more conspicuous when differences in body size were greater, whereas similar sized pairs shared parental tasks. These results suggest that the amount of parental care is largely affected by the relative size within pairs independent of sex in J. ornatus. However, the frequencies of defensive behaviours were not different in both female-largest and malelargest pairs. This indicates that parental roles would not completely change as the change of the body size difference within pairs. The larger parents were socially dominant over the partners regardless of sex, and observations of aggressive behaviours within pairs suggest that the larger fish are likely to make the partners perform parental care. Higher frequencies of aggressive encounters were observed in the similar-sized pairs than in the different-sized ones. Higher costs associated with frequent aggressive behaviours in the similar-sized pairs may be related to their small brood size, and may be partly responsible for the size-assortative mating with sexual size difference in this fish.

Status-dependent and strategic growth adjustments in female cooperative cichlids

“…Moreover, if the breeder female is removed from the group, helper females gaining the dominant position should increase their growth rate compared to control females. Alternatively, breeder females may fail to show a higher growth rate compared to helper females because they tailor their growth to the size difference with the breeder male (see also Munday et al 2006;Awata and Kohda 2004). If females show strategic growth, helper females living with a relatively large breeder female should increase their growth compared to helper females living with a relatively small breeder female.…”

The use of multiple sources of social information in contest behavior: testing the social cognitive abilities of a cichlid fish

“…In large social groups, especially those with dominance hierarchies (Jordan et al, 2010a,b) individuals frequently interact with familiar and unfamiliar group members, and also with unknown individuals from outside the group (e.g., Byrne and Whiten, 1988;Awata and Kohda, 2004;White and Gowan, 2013). Increased cognitive abilities will be favored if they allow individuals to indirectly infer their dominance relationship with unknown individuals and avoid costly aggressive interactions for dominance.…”

“…Cooperatively breeding cichlids in Lake Tanganyika often have large groups associated with frequent social interactions with known and unknown individuals (e.g., Awata et al, 2005;Heg and Bachar, 2006;Wong and Balshine, 2010), which may favor the development of high cognitive abilities (e.g., Byrne and Whiten, 1988;Bond et al, 2003;Alfieri and Dugatkin, 2011). Julidochromis transcriptus and its congeners are cooperatively breeding cichlids with a highly organized social system (Awata and Kohda, 2004;Awata et al, 2005Awata et al, , 2006Awata et al, , 2008Awata et al, , 2010Heg and Bachar, 2006;Kohda et al, 2009). Breeding groups consist of multiple unrelated males and females that frequently share paternity and cooperatively raise their brood (Awata et al, 2005).…”

“…Breeding groups consist of multiple unrelated males and females that frequently share paternity and cooperatively raise their brood (Awata et al, 2005). Breeding members frequently interact with each other, but strangers of varying social status often approach the territory or nests of the members (Awata and Kohda, 2004). This fish is therefore an ideal species in which to examine social cognitive capacity, and is amenable to experimental manipulation of social experiences.…”

Sexual Conflict between Parents: Offspring Desertion and Asymmetrical Parental Care

“…Although the larger (or physically stronger) individuals in a pair can "force" the smaller parent to care, reports of physical coercion are rare (Awata and Kohda 2004). There may be three reasons for this.…”