Recherche

O'Connor, Constance M.; Marsh-Rollo, Susan E.; Aubin-Horth, Nadia; Balshine, Sigal — 2016-01-28 Comparative studies have revealed that vasopressin-oxytocin pathways are associated with both pair bonding and grouping behaviour. However, the relationship between pair bonding and grouping behaviourremains unclear.In this study,our aim was to identify whether two species that differ in grouping behaviourdisplay a corresponding difference in their pair bonds, and in the underlying vasopressin-oxytocinhormonal pathways. Using two species of cichlid fishes, the highly social Neolamprologuspulcher and the non-social Telmatochromis temporalis, we measuredproximity of pairs during pair bond formation, and then measured social behaviors (proximity, aggression, submission,affiliation)and brain gene expression of isotocin and arginine vasotocin (the teleost homologues of oxytocin and vasopressin, respectively), as well as their receptors, after a temporary separation and subsequent reunion of the bonded pairs. Pairs of the social species spent more time in close proximity relative to the non-social species. Rates of aggression increased in both species following the separation and reunion treatment, relative to controls that were not separated.Overall, whole brain expression of isotocin was higher in the social species relative to the non-social species, and correlated with proximity, submission, and affiliation, but only in the social species. Our results suggest that both a social and a non-social cichlid species have similar behavioural responses to a temporary separation from a mate, and we found no differencein the brain gene expression of measured hormones and receptors based on our separation-reunion treatment. However, our results highlight the importance of isotocin in mediating submissive and affiliativebehaviourin cichlid fishes, and demonstrate thatisotocinhas species-specific correlations with socially relevantbehaviours.

Jindal, Shagun; Bose, Aneesh P.H.; O'Connor, Constance M.; Balshine, Sigal; Bose, Aneesh P. H. — 2017-02-08 Infanticide and offspring cannibalism are taxonomically widespread phenomena. In some group-living species, a new dominant individual taking over a group can benefit from infanticide if doing so induces potential mates to become reproductively available sooner. Despite widespread observations of infanticide (i.e. egg cannibalism) among fishes, no study has investigated whether egg cannibalism occurs in fishes as a result of group takeovers, or how this type of cannibalism might be adaptive. Using the cooperatively breeding cichlid, Neolamprologus pulcher, we tested whether new unrelated males entering the dominant position in a social group were more likely to cannibalize eggs, and whether such cannibalism would shorten the interval until the female's next spawning. Females spawned again sooner if their broods were removed than if they were cared for. Egg cannibalism occurred frequently after a group takeover event, and was rarer if the original male remained with the group. While dominant breeder females were initially highly aggressive towards newcomer males that took over the group, the degree of resistance depended on relative body size differences between the new pair and, ultimately, female aggression did not prevent egg cannibalism. Egg cannibalism, however, did not shorten the duration until subsequent spawning, or increase fecundity during subsequent breeding in our laboratory setting. Our results show that infanticide as mediated through group takeovers is a taxonomically widespread behaviour. https://creativecommons.org/publicdomain/zero/1.0/

Bose, Aneesh P H; Cogliati, Karen M; Luymes, Nick; Bass, Andrew H; Marchaterre, Margaret A; Sisneros, Joseph A; Bolker, Benjamin; Balshine, Sigal; Bolker, Benjamin M — 2018-01-02 A male’s reproductive success often depends on both his phenotypic quality and the quality of the resources he controls. An important and longstanding challenge for evolutionary biologists has been to disentangle these two often-correlated factors. Here, we present a large multi-year, multi-population field study along with complementary laboratory experiments aimed at disentangling the effects of male quality and nest quality in driving male reproductive success in the plainfin midshipman fish, Porichthys notatus. We investigate how these factors are linked to reproductive success using a number of different reproductive success components, including female attraction, cuckolder male attraction, egg acquisition, and rearing success. We show in the field that both male size and nest size are important correlates of reproductive success in this paternal care-giving species, but also that nest size can impose a limit on reproductive success regardless of the quality of the male nest owner. Females in the laboratory prefer large males when nest size is held constant, but females show no detectable preference for larger nests when nest size is varied and male size is held constant. We also explore a suite of additional male and nest traits – including male body condition, sonic organ investment, nest species richness, and nest density. Our results highlight how male and resource quality are multivariate concepts that incorporate information from the male phenotype, the ecological environment, and even the social environment and shape mating systems by influencing an animal’s choice of mating partners and nesting sites.

Pepler, Meghan; Hindra, Hindra; Miller, Jessica; Elliot, Marie; Balshine, Sigal — 2021-03-09 <p>Males of some species possess extra reproductive organs called accessory glands which are outgrowths of the testes or sperm duct. These organs have a well-established role in reproduction; however, they also appear to have other important functions that are less understood. Here we investigate the function of the highly complex accessory glands of a marine toadfish, <em>Porichthys notatus, </em>a fish with two reproductive male types: large care-providing ‘guarder’ males and small non-caring ‘sneaker’ males. While both male types have accessory glands, guarder male accessory glands are much larger relative to their body size. We show that accessory gland fluids strongly inhibit the growth of bacterial genera associated with unhealthy eggs and have no effect on the growth of strains isolated from healthy eggs. This antibacterial effect was particularly pronounced for extracts from guarder males. Furthermore, we demonstrate that both healthy and unhealthy plainfin midshipman eggs have diverse but distinct microbial communities that differ in their composition and abundance. The highly specific inhibitory capacity of accessory gland fluid on bacteria from unhealthy eggs was robust across a wide range of ecologically relevant temperatures and salinities. Collectively, these ecological and molecular observations suggest a care function for the accessory gland, mediated by antimicrobial agents.</p>

Brown, Nicholas; Houpt, Noah; Yee, Nicole; Curtis, Jennifer; Bolker, Benjamin; Juanes, Francis; Balshine, Sigal — 2020-10-29 These data were used to investigate variation in the costs and benefits of nesting at various positions along an intertidal gradient. These data were collected from one laboratory and two field experiments carried out in 2018 and 2019. The focal species, the plainfin midshipman <i>Porichthys notatus</i>, is a marine toadfish that nests in the intertidal and shallow subtidal zones of beaches along the Pacific Coast of North America.