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Assoc. Prof. Patricia Backwell
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Main Research Interest
Behavioural ecology of fiddler crabs
(Female mate sampling behaviour, deceptive communication, fighting and territoriality).
Background
I received my formal education in South Africa. During my graduate years I worked on the breeding behaviour of several species of frogs. After my PhD I switched to studying fiddler crabs and completed three post-docs. I then did a year of lecturing in South Africa before moving to Panama to work for the Smithsonian for the next six years, still studying fiddlers. I took up my present post as lecturer at ANU at the start of 2002. All of this experience has forged me into the truly brilliant scientist that I am.
My current research is entirely field-based and I have spent many hours sitting on sunny beaches staring at amazing little crabs. Most of my fieldwork has been carried out in Mozambique, Japan, South Africa and Central America. I am now working on tropical Australian fiddlers. My study site is in Darwin, NT.
Research
I work on the behavioural ecology of fiddler crabs. There are over 100 species of fiddlers world wide, and about 20 of them occur in Australia. They are often the most commonly seen inter-tidal animal on tropical mudflats, and are ecologically important as a major food source for shore birds. Although a lot is known about them as prey items, surprisingly little is known about their behaviour. They are ideal study animals because they occur in huge numbers and are exceptionally easy to catch, mark, observe and manipulate. They are sexually dimorphic, males having a single enlarged claw which is used both as a weapon and waved to attract mate-searching females.
My work has covered a broad range of topics but I have concentrated on three main areas:
THE MATE CHOICE PROCESS
I am particularly interested in the process of mate selection. In most animal species, females have inherent mating preferences that can be demonstrated in simple laboratory studies involving two-choice tests. Under natural conditions, however, the actual process of mate choice is far more complex. There are many constraints that may prohibit females from expressing their preferences. They may face temporal or energetic constraints on free choice. Predation risk or variation in the quality of resources they encounter may affect their final choice. Similarly, variation in the social environment, such as male-male competition, levels of male phenotypic variation or operational sex ratios could influence their selection of mates. Much of my research focuses on the biotic and abiotic factors that determine the level at which females are able to express their underlying mating preferences.
DISHONEST SIGNALLING
In animal communication it is generally true that the signals animals use convey accurate and honest information. Individuals of some species, however, produce deceptive signals that provide inaccurate information. This "cheating" may allow the signaller to attract mates or repel competitors when it would be incapable of doing so were it to signal honestly. Some fiddler crabs appear to signal deceptively. Fiddlers can autotomise their large claw and, through a series of moults, regenerate a new one. In most fiddler species, the regenerated claw is identical to the original. In some species, however, the regenerated claw is clearly different. It lacks teeth, has a smaller muscle mass and more delicate fingers. Males apparently quickly regenerate their claw to the same overall length as the original, but produce a cheaper version. This is less effective as a weapon but is lighter and therefore more easily waved. The regenerated claw appears to act as an effective visual bluff of fighting ability and may actually be preferred by mate searching females. I am presently investigating this apparent case of cheating.
FIGHTING NEIGHBOURS AND STRANGERS
Male fiddlers use their enlarged claws in fights. First they threaten each other with aggressive waves, then they push each other with the front surface of the claw, and finally they interlock claws and grapple until one male, the loser, is flicked away. Territory owners fight approaching strangers that try to usurp their territories. They also fight neighbours to negotiate and demarcate territory boundaries. Strangers pose a greater threat than neighbours because losing a fight with a stranger means losing the entire territory whereas losing a fight with a neighbour only results in a slight reduction in territory size. In other animals, fights with both strangers and neighbours are thought to be tests of strength with the stronger male most likely to win. Oddly, in fiddler crabs, this does not appear to be the case. Fights between neighbours do not appear to be settled by brute force. Instead, it appears that residents use aggression as a sort of punishment against encroaching neighbours. The fight itself inflicts time and energy costs on the neighbour so, by consistently engaging the neighbour in a fight each time it encroaches, residents may decrease the likelihood of the neighbour returning to the disputed area. If this is true, then fights between neighbours and those between strangers are fundamentally different interactions. While strangers might fight to win, neighbours may not be trying to 'beat' the encroacher but rather to 'nag' it into respecting the border between them.
Current Students
- Tanya Detto (PhD candidate, Co-supervised with Jochen Zeil of RSBS) 2003-onward
- Leeann Reaney (PhD candidate) 2004-onward
- Sarah Fayed (Honours student) 2006-2007
- Elisha Curran (Honours student) 2007
- Richard Milner (Honours student) 2007
Past Students
- Nathan Jardine (Honours student) 2003-2004
- Alex McWilliam (Honours student) 2004-2005
- Desley Darby (Honours student) 2004-2005
- Katrina Reading (Honours student) 2005-2006
Current Funding
- ARC Discovery Grant (2004-2007) ($200,000). Fighting strangers and neighbours
Publications 2004-09
For a full list of publications and PDFs, see My Web site
Kinnear, M., Smith, L.M.A., Maurer, G., Backwell, P.R.Y., Linde, C.C. 2009. Polymorphic microsatellite loci for paternity analysis in the fiddler crab Uca mjoebergi. Journal of Crustacean Biology 29(2): 273-274.
Booksmythe, I., Detto, T., Backwell, P.R.Y. 2008. Female fiddler crabs settle for less: the travel costs of mate choice. Animal Behaviour 76: 1775-1781.
Fayed, S.A., Jennions, M.D., Backwell, P.R.Y. 2008. What factors contribute to an ownership advantage? Biology Letters 4: 143-145.
Milner, R.N.C., Jennions, M.D., Backwell, P.R.Y. 2008. Does the environmental context of a signalling male influence his attractiveness? Animal Behaviour 76: 1565-1570.
Reaney, L.T., Milner, R.N.C., Detto, T., Backwell, P.R.Y. 2008. The effects of claw regeneration on territory ownership and mating success in the fiddler crab Uca mjoebergi . Animal Behaviour 75: 1473-1478.
Reaney, L.T., Sims, R.A., Sims, S.W.M., Jennions, M.D., Backwell, P.R.Y. 2008. Experiments with robots explain synchronized courtship in fiddler crabs. Current Biology 18(2): R62-R63.
Slatyer, R.A., Fok, E.S.Y., Hocking, R., Backwell, P.R.Y. 2008. Why do fiddler crabs build chimneys? Biology Letters 4: 616-618.
Backwell, P.R.Y., Matsumasa, M., Double, M., Roberts, A., Murai, M., Keogh, J.S., Jennions, M.D. 2007. What are the consequences of being left-clawed in a predominantly right-clawed fiddler crab? Proceedings of the Royal Society 274: 2723-2729.
Reading, K.L., Backwell, P.R.Y. 2007. Can beggars be choosers? Male mate choice in a fiddler crab. Animal Behaviour 74: 867-872.
Reaney, L.T., Backwell, P.R.Y. 2007. Temporal constraints and female preference for burrow width in the fiddler crab, Uca mjoebergi . Behavioral Ecology and Sociobiology 61: 1515-1521.
Reaney, L.T., Backwell, P.R.Y. 2007. Risk-taking behavior predicts aggression and mating success in a fiddler crab. Behavioral Ecology 18: 521-525.
Backwell, P., Jennions, M., Wada, K., Murai, M., Christy, J., (2006) “Synchronous waving in two species of fiddler crabs”, Acta Ethologica, Vol 9, pp 22-25.
Christy, J.H., Backwell, P.R.Y. (2006) No preference for exaggerated courtship signals in a sensory trap. Animal Behaviour 71: 1239-1246.
Detto, T., Backwell, P., Hemmi, J., Zeil, J., (2006) “Visually mediated species and neighbour recognition in fiddler crabs (Uca mjoebergi and Uca capricornis)”, Proceedings of the Royal Society of London Series B: Biological Sciences, Vol 273, pp 1661-1666.
Murai, M., Backwell, P., (2006) “A conspicuous courtship signal in the fiddler crab Uca perplexa: female choice based on display structure”, Behavioral Ecology and Sociobiology, Vol 60, pp 736-741.
Zeil, J., Hemmi, J., Backwell, P., (2006) “Fiddler crabs”, Current Biology, Vol 16, Issue 2, pp R40-R41.
Morrell, L., Backwell, P., Metcalfe, N., (2005) "Fighting in fiddler crabs Uca mjoebergi : what determines duration?", Animal Behaviour, Vol 70, pp 653-662.
Murai, M., Backwell, P., (2005) "More signalling for earlier mating: conspicuous male claw waving in the fiddler crab, Uca perplexa ", Animal Behaviour, Vol 70, pp 1093-1097.
Backwell, P., (2004) "Cheats Prosper", in An ABC of Lying: Taking Stock in Interesting Times, Livio Dobrez, Patricia Dobrez, Jan Lloyd Jones (eds) 1st Edition edition, Australian Scholarly Publishing Pty Ltd, Melbourne, Australia, pp 227-232.
Backwell, P., Jennions, M., (2004) "Coalition among male fiddler crabs", Nature, Vol 430, pp 417.
Selected Publications
Backwell, P.R.Y., Jennions, M.D. (2004) Coalitions among male fiddler crabs. Nature 430: 417.
Backwell, P.R.Y., Jernnions, M.D., Passmore, N.I., Christy, J.H. (1998) Synchronous waving in a fiddler crab. Nature 391: 31-32.
Backwell, P.R.Y., Christy, J.H., Telford, S.R., Jennions, M.D., Passmore, N.I. (2000) Dishonest signalling in a fiddler crab. Proceedings of the Royal Society B 267: 1-6.
Koga, T., Backwell, P.R.Y., Jennions, M.D., Christy, J.H. (1998) Elevated predation risk changes mating behaviour and courtship in a fiddler crab. Proceedings of the Royal Society B 265: 1385-1390.
Detto, T., Backwell, P.R.Y., Hemmi, J., Zeil, J. (2006) Visually mediated species and neighbour recognition in fiddler crabs (Uca mjoebergi and Uca capricornis) . Proceedings of the Royal Society B (in press)
Backwell, P.R.Y., Passmore, N.I. (1996) Time constraints and multiple choice criteria in the sampling behaviour and mate choice of the fiddler crab, Uca annulipes. Behavioural Ecology and Sociobiology 38: 407-416.
Christy, J.H., Backwell, P.R.Y., Schober, U. (2003) Inter-specific attractiveness of structures built by courting male fiddler crabs: experimental evidence of a sensory trap. Behavioural Ecology & Sociobiology 53: 84-91.
Jennions, M.D., Backwell, P.R.Y. (1998) Variation in courtship rate in the fiddler crab Uca annulipes : is it related to male attractiveness? Behavioural Ecology 9: 605-611.
Backwell, P.R.Y., O'Hara, P.D., Christy, J.H. (1998) Prey availability and selective foraging in shorebirds. Animal Behaviour 55: 1659-1667.
Backwell, P.R.Y. and Jennions, M.D. (1993) Mate choice in Hyla ebbraccata : sexual selection, mate recognition and signal selection. Animal Behaviour 45: 1248-1250.
Teaching
Most of my teaching is in the following two courses:
Animal Evolution and Ecology: BIOL1005
This is a first year course in which I teach the segment on invertebrates. Invertebrates are an extremely diverse group of animals that include jellyfish, worms, snails, crabs, octopusin fact, if it hasn't got fur, scales or feathers, it's probably an invertebrate. Like all animals, invertebrates face the ubiquitous problems of having to feed, breath, avoid their predators and successfully reproduce. Being such a diverse group, invertebrates have solved these problems in a huge variety of ways. This course looks at some of those solutions. For example, some male octopus have arms that break off and wiggle through the female reproductive system to hand-deliver the sperm to the unfertilised eggs; and in some worms all the adults gather together and explode, killing the entire population but releasing the gametes to start the next generation.
Marine Biology: BIOL2112
This is a second year course which I co-ordinate and partly teach. I teach the section on marine invertebrates. I discuss the weird species that live on the deep, dark sea floor like the eyeless shrimp and the hairy worms. I also discuss open water species like the elusive 15m long giant squid that nobody has ever seen alive. I then discuss coral reef invertebrates and the incredible levels of symbiosis found in this environment. Finally I discuss inter-tidal animals that live on rocky shores, sandy beaches, mangroves and mudflats, including my particular favourite - the fiddler crab.
Possible Honours Projects
I am interested in supervising honours projects in behavioural ecology, particularly on crustaceans. I have several possible projects that involve field-based research in Queensland. You can find details for individual projects on my web site or contact me to discuss your own ideas for projects.
