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Brian Wisenden

Abstract

Chemical cues released from injured fish skin during a predator attack provide reliable information about the presence of predation risk. Here, I report estimates of the area avoided by littoral fishes after experimental release of chemical alarm cues in two small lakes in northern Minnesota. Minnow traps were labeled chemically with either water (control) or skin extract (chemical alarm cue) made from 2 cm2 of cyprinid skin (redbelly dace in experiment 1, fathead minnows in experiment 2). Traps labeled with water were placed 1, 2, or 8 m from traps labeled with alarm cue. After 2 h, water-traps that were either 1 or 2 m distant from an alarm-trap caught significantly fewer fish than water-traps 8 m distant from alarm-traps. Conspecific and heterospecific skin extract produced similar area avoidance by fathead minnows. Redbelly dace showed a larger active space in response to conspecific than heterospecific alarm cues. Brook stickleback showed reduced catches within 2 m of skin extract of fathead minnows. Overall, the radius of active space was between 2 and 8 m under lake conditions with average subsurface currents of 0.82 cm/s. These data are the first field estimates of active space of ostariophysan chemical alarm cues.

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Shireen Alemadi and Brian Wisenden

Abstract

Injury-released chemical alarm cues are released when predators attack aquatic prey. These cues are generally released only in this context and as such, conspecific alarm cues form an important component of risk assessment. Minnows (Ostariophysi, Cyprinidae) possess a well-developed chemical alarm system. However, minnows do not respond to conspecific injury-released alarm cues until 30 to 50 d post-hatch. Non-ostariophysan fishes respond to chemical alarm cues with antipredator behavior but the ontogeny of this behavior is not known for any species. Here, we test convict cichlids (Acanthopterygii: Cichlidae), a species known to respond to alarm cues as adults. Convict cichlid parents care for their eggs and defend their developing young from predators for 4 to 6 weeks. In our experiment, we tested the ontogeny of antipredator response to chemical alarm cues in young convict cichlids well within and just beyond the size range typically defended by parents. We found that small convict cichlid young of a size typically defended by parents engaged in area avoidance and grouping behaviors in response to alarm cues and did so as effectively as young that would typically be independent of parental care.

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Linda Fuselier, Mathew Rugg, Nichole Korpi and Brian Wisenden

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Randy Sutrisno, Brian D. Wisenden, Cory D. Sailer and Sonny J. Radenic

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Stacey S.Y. Lee-Jenkins, Myron L. Smith, Brian D. Wisenden, Alex Wong and Jean-Guy J. Godin

Mobile young under parental care have a high potential for intermixing with other broods, which potentially increases the costs to the foster parents. Here, we examined for the first time the genetic composition of wild-caught broods of the convict cichlid (Amatitlania siquia), a socially monogamous biparental fish, for evidence of brood mixing and adoption. Our microsatellite genotyping data revealed that 79% of broods contained adopted young. Moreover, 25% of broods contained adopted sibsets likely arising from extra-pair matings, a phenomenon hitherto not documented for this species. Overall, adopted foreign fry and host fry in mixed broods were generally different in body length, as would be expected if they have different parents. However, fry from possible extra-pair matings were similar in body length to host fry, suggesting that they are of similar age. Our results are important because they reveal a very high prevalence and degree of brood mixing, and indicate that social monogamy does not necessarily lead to genetic monogamy in the convict cichlid in nature. These findings raise questions about potential brood-mixing mechanisms and the reproductive ecology (especially opportunities for polygamy in nature) of this important model species in the study of animal behaviour.

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Philippe Vernier, Evan J. Kyzar, Caio Maximino, Keith Tierney, Michael Gebhardt, Merlin Lange, Suresh Jesuthasan, Adam Michael Stewart, Stephan C.F. Neuhauss, Kyle Robinson, William Norton, Anderson Manoel Herculano, Jonathan Cachat, Vincent Tropepe, Samuel Landsman, Brian Wisenden, Laure Bally-Cuif and Allan V. Kalueff