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Risk-sensitive antipredator behavior in the Trinidadian guppy, Poecilia reticulata (2008)
Journal Article
Botham, M. S., Hayward, R. K., Morrell, L. J., Croft, D. P., Ward, J. R., Ramnarine, I., & Krause, J. (2008). Risk-sensitive antipredator behavior in the Trinidadian guppy, Poecilia reticulata. Ecology, 89(11), 3174-3185. doi:10.1890/07-0490.1

The comparative approach has become a powerful tool for understanding how predation has shaped prey behavior. In this study we recorded the occurrence of common aquatic predator species and their densities in seven natural populations of Trinidadian... Read More

Shoal composition determines foraging success in the guppy (2008)
Journal Article
Dyer, J. R. G., Croft, D. P., Morrell, L. J., & Krause, J. (2009). Shoal composition determines foraging success in the guppy. Behavioral ecology, 20(1), 165-171. doi:10.1093/beheco/arn129

The composition of an animal group can impact greatly on the survival and success of its individual members. Much recent work has concentrated on behavioral variation within animal populations along the bold/shy continuum. Here, we screened individua... Read More

Association patterns and foraging behaviour in natural and artificial guppy shoals (2008)
Journal Article
Morrell, L. J., Croft, D. P., Dyer, J. R. G., Chapman, B. B., Kelley, J. L., Laland, K. N., & Krause, J. (2008). Association patterns and foraging behaviour in natural and artificial guppy shoals. Animal behaviour, 76(3), (855-864). doi:10.1016/j.anbehav.2008.02.015. ISSN 0003-3472

Animal groups are often nonrandom assemblages of individuals that tend to be assorted by factors such as sex, body size, relatedness and familiarity. Laboratory studies using fish have shown that familiarity among shoal members confers a number of be... Read More

Optimal individual positions within animal groups (2008)
Journal Article
Morrell, L., & Romey, W. L. (2008). Optimal individual positions within animal groups. Behavioral ecology, 19(4), 909-919. doi:10.1093/beheco/arn050

Animal groups are highly variable in their spatial structure, and individual fitness is strongly associated with the spatial position of an animal within a group. Predation risk and food gains are often higher at the group peripheries; thus, animals... Read More

Mechanisms for aggregation in animals: Rule success depends on ecological variables (2007)
Journal Article
Morrell, L. J., & James, R. (2008). Mechanisms for aggregation in animals: Rule success depends on ecological variables. Behavioral ecology, 19(1), 193-201. doi:10.1093/beheco/arm122

Under the threat of predation, animals often group tightly together, with all group members benefiting from a reduction in predation risk through various mechanisms, including the dilution, encounter-dilution, and predator confusion effects. Addition... Read More

Early interactions with adults mediate the development of predator defenses in guppies (2007)
Journal Article
Chapman, B. B., Morrell, L. J., Benton, T. G., & Krause, J. (2008). Early interactions with adults mediate the development of predator defenses in guppies. Behavioral ecology, 19(1), 87-93. doi:10.1093/beheco/arm111

Antipredator defenses in many species have been shown to exhibit phenotypic plasticity in response to variable predation risk. Some evidence suggests that in certain species adults act as proxy predators, triggering the development of adaptive defens... Read More

Consensus decision making in human crowds (2007)
Journal Article
Dyer, J. R. G., Ioannou, C. C., Morrell, L. J., Croft, D. P., Couzin, I. D., Waters, D. A., & Krause, J. (2008). Consensus decision making in human crowds. Animal behaviour, 75(2), (461-470). doi:10.1016/j.anbehav.2007.05.010. ISSN 0003-3472

In groups of animals only a small proportion of individuals may possess particular information, such as a migration route or the direction to a resource. Individuals may differ in preferred direction resulting in conflicts of interest and, therefore,... Read More

A cost of leadership in human groups (2007)
Journal Article
Piyapong, C., Morrell, L. J., Croft, D. P., Dyer, J. R. G., Ioannou, C. C., & Krause, J. (2007). A cost of leadership in human groups. Ethology, 113(9), (821-824). doi:10.1111/j.1439-0310.2007.01382.x. ISSN 0179-1613

Group living is the result of a dynamic trade-off between associated costs and benefits. However, these costs and benefits are not necessarily distributed equally across different spatial positions of groups which may result in different fitness retu... Read More

Diet, familiarity and shoaling decisions in guppies (2007)
Journal Article
Morrell, L. J., Hunt, K. L., Croft, D. P., & Krause, J. (2007). Diet, familiarity and shoaling decisions in guppies. Animal behaviour, 74(2), (311-319). doi:10.1016/j.anbehav.2006.10.021. ISSN 0003-3472

Animals are known to derive benefits from associating with familiar individuals, and familiarity is important in the structuring of animal groups. In fish, individuals are known to shoal preferentially with others they have previously spent time with... Read More

Why do female migratory birds arrive later than males? (2006)
Journal Article
Kokko, H., Gunnarsson, T. G., Morrell, L. J., & Gill, J. A. (2006). Why do female migratory birds arrive later than males?. The journal of animal ecology, 75(6), 1293-1303. doi:10.1111/j.1365-2656.2006.01151.x

1. In migratory birds males tend to arrive first on breeding grounds, except in sex-role reversed species. The two most common explanations are the rank advantage hypothesis, in which male-male competition for breeding sites drives stronger selection... Read More

From hawks and doves to self-consistent games of territorial behavior (2006)
Journal Article
Kokko, H., López-Sepulcre, A., & Morrell, L. J. (2006). From hawks and doves to self-consistent games of territorial behavior. The American naturalist, 167(6), (901-912). doi:10.1086/504604. ISSN 0003-0147

Explaining the "prior-residence effect" (automatic owner status of individuals who arrived first in an area) was one of the very first applications of game theory in animal behavior. These models, however, predict paradoxical solutions where intruder... Read More

Predation risk as a driving force for sexual segregation: A cross-population comparison (2006)
Journal Article
Croft, D., Morrell, L. J., Wade, A. S., Piyapong, C., Ioannou, C. C., Dyer, J. R. G., …Krause, J. (2006). Predation risk as a driving force for sexual segregation: A cross-population comparison. The American naturalist, 167(6), 867-878. doi:10.1086/504853

Sexual segregation is widespread throughout the animal kingdom. Although a number of hypotheses have been proposed to account for observed patterns, the generality of the mechanisms remains debated. One possible reason for this is the focus on segreg... Read More

Fighting in fiddler crabs Uca mjoebergi: what determines duration? (2005)
Journal Article
Morrell, L. J., Backwell, P. R., & Metcalfe, N. B. (2005). Fighting in fiddler crabs Uca mjoebergi: what determines duration?. Animal behaviour, 70(3), (653-662). doi:10.1016/j.anbehav.2004.11.014. ISSN 0003-3472

Contest duration in animals is often interpreted as being a consequence of mutual assessment of the difference in the competitors' resource-holding potential (RHP), allowing the inferior individual to avoid costly interactions it is likely to lose. D... Read More

Why are small males aggressive? (2005)
Journal Article
Morrell, L. J., Lindström, J., & Ruxton, G. D. (2005). Why are small males aggressive?. Proceedings. the Royal Society. Biological sciences /, 272(1569), 1235-1241. doi:10.1098/rspb.2005.3085

Aggression is ubiquitous in the animal kingdom, whenever the interests of individuals conflict. In contests between animals, the larger opponent is often victorious. However, counter intuitively, an individual that has little chance of winning (gener... Read More

Mate guarding, male attractiveness, and paternity under social monogamy (2005)
Journal Article
Kokko, H., & Morrell, L. (2005). Mate guarding, male attractiveness, and paternity under social monogamy. Behavioral ecology, 16(4), 724-731. doi:10.1093/beheco/ari050

Socially monogamous species vary widely in the frequency of extrapair offspring, but this is usually discussed assuming that females are free to express mate choice. Using game-theory modeling, we investigate the evolution of male mate guarding, and... Read More

Bridging the gap between mechanistic and adaptive explanations of territory formation (2004)
Journal Article
Morrell, L. J., & Kokko, H. (2005). Bridging the gap between mechanistic and adaptive explanations of territory formation. Behavioral Ecology and Sociobiology, 57(4), (381-390). doi:10.1007/s00265-004-0859-5. ISSN 0340-5443

How animals divide space can have fundamental implications for the population dynamics of territorial species. It has recently been proposed that space can be divided if animals tend to avoid fight locations, rather than the winner of fights gaining... Read More

Can too strong female choice deteriorate male ornamentation? (2004)
Journal Article
Morrell, L., & Kokko, H. (2004). Can too strong female choice deteriorate male ornamentation?. Proceedings. the Royal Society. Biological sciences /, 271(1548), 1597-1604. doi:10.1098/rspb.2004.2763

Competition for limited resources can have fundamental implications for population dynamics. However, the effects of resource depletion have rarely been discussed in the context of sexual selection, even though mate choice typically favours males who... Read More

Are behavioural trade-offs all they seem? Counter-intuitive resolution of the conflict between two behaviours (2004)
Journal Article
Morrell, L. J. (2004). Are behavioural trade-offs all they seem? Counter-intuitive resolution of the conflict between two behaviours. Behavioral Ecology and Sociobiology, 56(6), (539-545). doi:10.1007/s00265-004-0821-6. ISSN 0340-5443

The understanding of trade-offs between behaviours is fundamental to the study of animal behaviour. Individuals may often be faced with the choice of which of two mutually incompatible behaviours to perform. Here, I present a model investigating the... Read More

Adaptive strategies of territory formation (2003)
Journal Article
Morrell, L. J., & Kokko, H. (2003). Adaptive strategies of territory formation. Behavioral Ecology and Sociobiology, 54(4), 385-395. doi:10.1007/s00265-003-0663-7

How do territorial animals gain ownership of an area? Early modelling has considered the evolution of fighting when the winner can claim the right to the resource. Recently, alternative hypotheses have been offered where repeated interactions lead to... Read More