Formica Picea
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Conservation genetics and ecology of the endangered Black Bog Ant, Formica picea by Simon D. Rees A thesis submitted to the School of Biosciences of Cardiff University for the degree of Doctor of Philosophy May 2006 UMI Number: U584972 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 U584972 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 and Statements DECLARATION This work has not previously been accepted in substance for any degree and is not being concurrently submitted in candidature for any degree. Signed (candidate) Date /.$ ... >?.... ..................... STATEMENT 1 This thesis is the result of my own investigations, except where otherwise stated. Other sources are acknowledged by footnotes giving explicit references. A bibliography is appended. Signed (candidate) Date ......... STATEMENT 2 I herby 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 (candidate) Date ............ Summary In this study I aimed to investigate the genetic and ecological factors that may influence the distribution and conservation of the Black Bog Ant, Formica p/cea, within the UK, where it is classed as an endangered species. All main UK F. picea sites known at the start of this study (Cors Goch Llanllwch, Carmarthenshire; Rhossili Down, West Glamorgan; Hartland Moor, Dorset; the New Forest, Hampshire) were investigated. The first study of its kind of a UK ant species, this investigation involved measuring micro-geographic ecological parameters and using both microsatellite and mitochondrial DNA markers for genetic analyses. High percentage cover of Bell Heather (Erica tetraiix) and Deer Grass (Trichophorum cespitosum) in the immediate vicinity of the nest and a low density of Heather (Calluna vulgaris) in the local area occupied by F. picea appear to contribute to favourable habitat. Water table level may be the most influential determinant of F. picea nest distribution, however, as an unoccupied area appearing favourable in terms of E. tetraiix and T. cespitosum cover revealed significantly lower relative humidity and vegetation height in 2003. Colonies of all studied populations were highly polygynous, containing multiple reproducing queens per colony, and two populations revealed significant levels of inbreeding. Isolation by distance was detected in two populations, suggesting nest reproduction by budding and poor dispersal. All populations were genetically differentiated from one another, with the exception of the physically closest pair. Within Cors Goch Llanllwch a degree of social polymorphism was identified, with two sectors showing differing levels of polygyny and polydomy (multiple nests per colony). Aggression between non-nestmates was absent in this population, suggesting a largely unicolonial organisation. Despite relatively large population sizes conferred by polygyny, UK populations of F. picea are at risk due to ecological specificity, inbreeding and limited dispersal. Within this study I make suggestions for conservation management including detailed ecological analyses and colony relocation. Dedication This thesis is dedicated to Claire Rees, for support, patience and listening to the words “It’s nearly done now” for eight long months Acknowledgments I would like to sincerely thank the following people for their help and support throughout my PhD; my supervisors, Andrew Bourke (Institute of Zoology, London) and Mike Bruford (Cardiff University), for their continued guidance and patience; my advisor, Glenda Orledge (University of Bath), for advice, enthusiasm and help with fieldwork; Bill Jordan (Institute of Zoology), for genetics advice; Lin Gander (formerly Wildlife Trust for South and West Wales) for introducing me to the Welsh study sites, helping to collect samples and assisting in setting up the transects; Andy Abbott (Abbott Ecology) and Ray North for introducing me to the Hartland Moor and New Forest study sites, respectively; Mike Howe (Countryside Council for Wales), Sian Musgrave (National Trust), David Sheppard (English Nature), Diana Westerhoff (English Nature), Tim Brodie-James (English Nature) and Simon Weymouth (Forestry Commission) for permission to collect samples for genetic analysis; David Stradling (Whitley Wildlife Conservation Trust) and Graham Elmes (Centre for Ecology and Hydrology) for helpful advise; and everyone at the Institute of Zoology, London, for making my time there so enjoyable. Contents Chapter 1 - Introduction ________________________________________________ The importance of ants ___________________________________________________ 1_ Genetic and social structure in ants __________________________________________ 2 Factors affecting the persistence of ant populations _____________________________ 4 Formica picea ecology ___________________________________________________ 5 Project aims ___________________________________________________________ 7 Chapter 2 - Ecological requirements of the endangered Black Bog Ant, __________ Formica_picea______________________________________________ Abstract_______________________________________________________________ 9 Introduction ___________________________________________________________ TO Methods_____________________________________________________________ 13 ________ Establishment of nest-sampling transects_________________________________ 1K3 ________ Ecological parameters________________________________________________ T4 ________ Statistical methods__________________________________________________ 18_ Results______________________________________________________________ 20 ________ Random factor and interaction effects____________________________________ 20 ________ Nest sites vs. inhabited area controls____________________________________ 20 ________ Uninhabited area controls vs. inhabited area________________________ controls 2A_ ________ Phenology_________________________________________________________ 22 ________ Solarium volume____________________________________________________ 22 Discussion____________________________________________________________ 23 ________ Nest sites vs. inhabited area controls____________________________________ 23 ________ Uninhabited area controls vs. inhabited area________________________ controls 26 ________ Phenology_________________________________________________________ 28 Chapter 3 - Relatedness, queen number and mating systems of UK ___________ populations of Formica picea_____________________________________ Abstract______________________________________________________________ 45 Introduction ___________________________________________________________ 46 Methods_____________________________________________________________ 49^ ________ Genetic sampling___________________________________________________ 49^ ________ Genetic methods____________________________________________________ 51^ ________ Statistical methods__________________________________________________ 52 Results______________________________________________________________ 57^ ________ Re-sampling methods________________________________________________ 57_ ________ Analysis of error rates, linkage disequilibrium and Hardy-Weinberg equilibrium58 ________ Genetic diversity within populations_____________________________________ 59 ________ Inbreeding, worker relatedness and effective queen__________________ number 60^ Discussion____________________________________________________________ 63^ ________ Genetic relatedness of nestmate workers and inbreeding_____________________ 64 ________ Social polymorphism 67 Chapter 4 - Intra- and inter-population genetic spatial structuring and unicoloniality in Formica picea___________________________________ Abstract______________________________________________________________ 79^ Introduction ___________________________________________________________ 80^ Methods_____________________________________________________________ 83^ ________ Genetic sampling___________________________________________________ 83^ ________ Genetic methods____________________________________________________ 84 ________ Aggression tests____________________________________________________ 85 Statistical methods 87 Population genetic differentiation 87 Within-population isolation by distance 89 Population genetic bottlenecks 90 Worker aggression 91 Polydomy 91 Polydomous colony boundaries 93 Validation of method of detecting polydomous colony boundaries 94 Results 96 Population genetic differentiation 96 Within-population isolation by distance 98 Population genetic bottlenecks 98 Mitochondrial DNA 99 Worker aggression 99 Polydomous colony boundary model validation 100 Polydomy 100 Discussion 101 Population genetic differentiation 102 Within-population isolation by distance 104 Population genetic bottlenecks 104 Mitochondrial DNA 105 Worker aggression 106 Polydomous colony boundary model 107 Colony boundaries and polydomy