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Foraging, Personality and Parasites Investigations Into the Behavioural Ecology of Fishes

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Foraging, Personality and Parasites Investigations Into the Behavioural Ecology of Fishes Foraging, personality and parasites investigations into the behavioural ecology of fishes Elizabeth Loys Richards Organisms and Environment Research Group School of Biological Sciences University of Cardiff A dissertation submitted to the University of Cardiff in accordance with the requirements of the degree o f Doctor of Philosophy in the Faculty of Biological Sciences September 2010 UMI Number: U516528 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. Dissertation Publishing UMI U516528 Published by ProQuest LLC 2013. Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code. ProQuest LLC 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 DECLARATION This work has not previously been accepted in substance for any degree and is not concurrently submitted in candidature for any degree. Signed .^. ..........(candidate) Date P! .. J.?. j fr. Q.!J. STATEMENT 1 This thesis is being submitted in partial fulfillment of the requirements for the degree of f . lo J)..' (insert MCh, MD, MPhil, PhD etc, as appropriate) Signed .Vr: ... (candidate) D a te....... STATEMENT 2 This thesis is the result of my own independent work/investigation, except where otherwise stated. Other sources are acknowledged by explicit references. S ig n ed ................. (candidate) Date.... /.?. j.?. J...£.9.!!..... STATEMENT 3 I hereby give consent for my thesis, if accepted, to be available for photocopying and for inter-library loan, and for the title and summary to be made available to outside organisations. Signed <^ ^ A . (candidate) Date....... ! . 9. / J Z . Q .! A STATEMENT 4: PREVIOUSLY APPROVED BAR ON ACCESS I hereby give consent for my thesis, if accepted, to be available for photocopying and for inter-library loans after expiry of a bar on access previously approved by the Graduate Development Committee. Signed (candidate) Date..... The contents of Chapters 2 -5 and Appendices I and II in this thesis conform to the ethical policy of WALTHAM Centre for Pet Nutrition, and are covered by a confidentiality agreement. Chapters 6, 7 and 8 were independent studies funded by the Natural Environment Research Council and are covered by Cardiff University ethical policies and UK Home Office Licence procedures. Abstract Individual behaviour varies considerably between and within species to balance the demands of resource acquisition in an ever-changing environment. This thesis investigated three aspects of behavioural variations: the occurrence of a conservative foraging strategy whereby predators avoid novel prey; the interaction between boldness (an aspect of personality) and behaviour; and the effect of boldness, host sex and social contact on parasite transmission. It was postulated that a temperate fish species, the three-spined stickleback (Gasterosteus aculeatus) was more dietarily conservative than poeciliid fish species, and that solitary fish exhibited a more conservative foraging strategy than fish in shoals. The thesis tested the hypotheses that shy fish shoaled more than bold counterparts, virgin females were bolder than mated ones, and shy fish had a greater chance of acquiring a parasite infection from an infected shoal member due to their closer proximity within shoals than bold fish. In addition, it was hypothesised that host contact was the main factor influencing parasite transmission within fish shoals. Behavioural experiments, traditional parasitology and molecular techniques were used to test the hypotheses. Five fish species, and a directly-transmitted ectoparasite, were used as model organisms. Fish were tested individually and assessed within shoals for their avoidance of novel prey, shoaling behaviour and parasite loads. There was evidence for a conservative foraging strategy in the four tropical fish species (Poecilia reticulata, P. sphenops, Xiphophorus maculates, X hellerii) and in a temperate species (Gasterosteus aculeatus), with the latter having greater dietary conservatism. Social context did not affect dietary conservatism, and there were with no significant differences in conservatism between isolated fish and shoals. Also, guppies showed reduced acceptance of novel, conspicuously-coloured prey. Using molecular scatology, both prey and host species-specific DNA were detected in fish faecal samples so this methodology can be used in the future to examine diet in the wild. Guppies from two wild populations differed significantly in their relative boldness, but individuals within a single population were similar in their relative boldness and this was consistent over time. Boldness of fish was affected by mating, with virgin females being bolder than their mated counterparts. Also, boldness impacted on shoaling behaviour, shy fish forming larger and tighter shoals than bold conspecifics. This had consequences for parasite transmission, with shy fish having higher parasite loads and a greater change in parasite load across an infection period than their bold counterparts. Host contact was the main factor influencing transmission of a directly-transmitted ectoparasite within a group-living host species. Significantly more parasites were transmitted between hosts when hosts were in more frequent and prolonged contact. Acknowledgements I would firstly like to thank my supervisors at Cardiff University, Dr. Jo Cable and Dr. Rob Thomas, for their enduring support, encouragement and valuable comments. We have had many interesting discussions, and 1 am indebted to them both for sharing with me their vast subject knowledge and sheer enthusiasm for what they do. I must also thank the Natural Environmental Research Council (NERC) for funding this work, and my CASE partner, the Waltham Centre for Pet Nutrition, for providing additional financial support. I am grateful to both my supervisors at Waltham, Dr. Lucy Alexander and Dr. Donna Snellgrove, for their support and encouragement. I am also very grateful to Dr. Cock van Oosterhout from Hull University, for his constructive criticism, attention to detail and statistical knowledge. Thanks must also go to Dr. Pati Faria and Dr. Andy King (both formally of Cardiff University) for assistance with my first steps into the world of molecular ecology. In addition, my thanks go to Dr. Nicola Marples (University College Dublin), for her pertinent comments and general enthusiasm regarding Chapters 1 and 2, as well as Dr. Peter Ferns (Cardiff University) for recording the spectrophotometer measurements in Chapter 2. Also, 1 have had the pleasure of working with a number of Cardiff University project students - Amanda Petts, Sophie Potter, Charlotte McKinnel, Anis Abd-Latif, Raphael Girardin. 1 also enjoyed a fruitful collaboration with Dr. Bart Adriaenssens from Gothenburg University, Sweden, which was very rewarding as I learned a lot and made a friend along the way! I am indebted to Miss Linda Erlandsson for technical support with general fish and parasite culture maintenance. On a more personal note, I would like to say a huge thank you to my very good friends, old and new, for their constant support and encouragement, and for providing a stable foundation when I was in much need of it - Laura, Sian, Bettina, Linda, Viola, Alex, Marian, Sarah. Last, but not least, I couldn’t have done it without the love and support of my family, especially my mum and aunt, who have always helped me to go for my goals, been proud of my successes and encouraged me to see the lessons in the hard times. v Table of contents Title page..................................................................................................................................................i Declaration............................................................................................................................................. ii Confidentiality statement.................................................................................................................. iii Abstract............................................................................................................................................... iv Acknowledgements............................................................................................................................ v Table of contents......................................................................................................................... vi-ix List of Tables.................................................................................................................................x-xi List of Figures ........................................................................................................................... xii-xiii Chapter 1: Introduction 1.1: Shoaling behaviour 1 -3 1.2: Foraging behaviour........................................................................................................................ 3-5 1.3: Dietary Conservatism....................................................................................................................... 5-6 1.4: Learning...........................................................................................................................................6-7
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