Staff Profiles

Dr SD Twiss

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Contact Dr SD Twiss (email at s.d.twiss@durham.ac.uk)

Biography

My research encompasses four main areas: (1) Behavioural and evolutionary ecology, specifically empirical studies of individual mating decisions and reproductive behaviour. (2) Spatial behavioural ecology: the development and application of spatially explicit analytical and modelling procedures to studies of the evolution of animal behaviour. (3) Evolutionary ecology of colony formation and social dynamics within animal groups. (4) Use of spatial approaches to integrate knowledge of individual animal behaviour into Environmental Change Ecology.
My innovative approach to studies of animal behaviour has been to apply modern Geo-spatial analytical and spatially explicit modelling procedures, as developed in the field of Landscape Ecology, to long-term, empirical, field based studies of individual animal behaviour. This spatial emphasis allows me to examine individual behavioural decisions within their physical, social and genetic contexts, quantified at appropriately fine spatial and temporal scales. The aim of my research is to understand how heterogeneity in these contexts, quantified at the variety of hierarchical scales at which they impinge upon individuals, constrains or alters the behavioural decisions of individuals. This perspective provides a deeper understanding of those choices, and perhaps more importantly, how context sets the behavioural options amongst which individuals choose (e.g. habitat and mate choice decisions in relation to local availability and quality of these resources/mates). This approach is designed to explain more of the observed variation between individuals than can be achieved by viewing individuals in isolation, and thereby provide improved empirical data for testing and developing hypotheses. Further, individual behaviour, examined in such spatially explicit frameworks also provides new insights for testing and improving models of meta-population and population scale processes and for predicting responses to future environmental change. This is an important, but often neglected component of environmental change ecology, as the range of an individual’s preferences and responses is typically narrower than those measured for the population as a whole. As population change is largely a result of individual behaviour it is vital to understand how individuals react to their environment in order to predict population responses to natural or anthropogenic environmental change and the consequent impact on ecosystem and population structure and function. Further, most animal species have social constraints that affect their spatial habitat requirements (e.g. spatial requirement for successfully reproducing units), thus, effective prediction of individual, population and ecosystem responses to environmental change also necessitates an understanding of how local environment both determines and interacts with the social dynamics of species. Understanding how organisms interact with their changing environment at all of these hierarchical scales is fundamental to effective efforts to assess and mitigate undesirable effects of environmental change.
I have applied this approach to various studies and a range of taxa (Mammals, Birds, Insects), but the focus of my research is a long-term (currently 19 years) study of breeding grey seals at various Scottish island colonies, in particular that of North Rona. My grey seal research is conducted in collaboration with Dr Paddy Pomeroy at the Sea Mammal Research Unit (University of St. Andrews) and is supported by UK Natural Environment Research Council (NERC) Fellowships, Grants and Core funding. The study benefits from over 5000 known and genetically typed individuals and the integration of individual reproductive histories within the accurately quantified physical, social and genetic contexts provided by my sub-metre accurate Geographical Information System (GIS) databases. My application of this spatially explicit approach to behavioural studies has proved highly productive, providing novel and key insights into the environmental causes of individual variation in behaviour and success that drive population and ecosystem scale processes. I am keen to extend my research approach to other pinniped species and ecosystems, both nationally and internationally, to provide an integrative examination of the effects of environmental change on individuals, populations and ecosystems at a range of spatial and temporal scales.

Indicators of Esteem

• 2001: Invited presentation: Ed Gregr & Sean Twiss at the "Use of Geomatic Technologies for Marine Mammal Scientists: workshop for the 14th Biennial Conference on the Biology of Marine Mammals (2001).

Research Interests

• Breeding Behaviour In Relation To Fine Scale Physical, Social And Genetic Landscapes
• Geographical Information Systems (Gis)
• Landscape Behavioural Ecology
• Vertebrate Mating Pattern Research - Specifically Grey Seal

Publications

Edited works: conference proceedings

• Pomeroy PP., Twiss SD. & Matthiopoulos J (2005) (2005). Associations of breeding grey seals persist at sea. 16th Biennial Conference on the Biology of Marine Mammals, San Diego.
• Twiss SD., Thomas CJ. & Pomeroy PP. (2005). Local weather affects the degree of polygyny in breeding grey seals (Halichoerus grypus). 16th Biennial Conference on the Biology of Marine Mammals, San Diego.

Journal papers: academic

• Twiss, SD, Culloch, RM & Pomeroy, PP (2012). An in-field experimental test of pinniped behavioral types. Marine Mammal Science 28(3): E280-E294.
• Twiss, S.D., Cairns, C., Culloch, R.M., Richards, S.A. & Pomeroy, P.P. (2012). Variation in Female Grey Seal (Halichoerus grypus) Reproductive Performance Correlates to Proactive-Reactive Behavioural Types. PLoS ONE 7(11): e49598.
• Twiss, SD & Franklin, J (2010). Individually consistent behavioural patterns in wild, breeding male grey seals (Halichoerus grypus). Aquatic Mammals 36(3): 234-238.
• Poland, V.F., Pomeroy, P.P., Twiss, S.D. & Graves, J.A. (2008). Fine-scale study finds limited evidence of kin clustering in a gray seal colony. Marine Mammal Science 24(2): 371-387.
• Twiss, S. D., Thomas, C. J., Poland, V. F. Graves, J. A. & Pomeroy, P. P. (2007). The impact of climatic variation on the opportunity for sexual selection. Biology Letters 3(1): 12-15.
• Jupp, T. E. & Twiss, S. D. (2006). A physically motivated index of sub-grid scale pattern. Journal of Geophysical Research – Atmospheres. . Journal of Geophysical Research – Atmospheres 111: D19112.
• Twiss SD., Pomeroy PP., Graves JA. & Poland VF. (2006). Finding fathers: Spatio-temporal analysis of paternity assignment in grey seals (Halichoerus grypus). Molecular Ecology 15(7): 1939-1953.
• Pomeroy PP., Redman PR., Ruddell SJS., Duck CD. & Twiss SD. (2005). Breeding site choice fails to explain interannual associations of female grey seals. Behavioural Ecology & Sociobiology 57(6): 546-556.
• Bean K., Amos W., Pomeroy PP., Twiss SD., Coulson TN. & Boyd IL. (2004). Patterns of parental relatedness and pup survival in the grey seal (Halichoerus grypus). Molecular Ecology 13(8): 2365-2370.
• Twiss SD., Duck C. & Pomeroy PP. (2003). Grey seal (Halichoerus grypus) pup mortality not explained by local breeding density on North Rona, Scotland. J Zool Lond 259(1): 83-91.
• Twiss SD., Wright NC., Dunstone N., Redman P., Moss S. & Pomeroy PP. (2002). Behavioral evidence of thermal stress from over-heating in UK breeding gray seals. Marine Mammal Science 18(2): 455-468.
• Redman, P., Pomeroy, PP. & Twiss SD. (2001). Grey seal maternal attendance patterns are affected by water availability on North Rona, Scotland. Can. J. Zool 79(6): 1073-1079.
• Pomeroy PP., Worthington Wilmer J., Amos W. & Twiss SD (2001). Reproductive performance links to fine scale spatial patterns of female grey seal relatedness. Proceedings of the Royal Society of London - Series B: Biological Sciences 268(1468): 711-717.
• Twiss SD., Thomas CJ. & Pomeroy PP. (2001). Topographic spatial characterisation of grey seal Halichoerus grypus breeding habitat at a sub-seal size spatial grain. Ecography 24(3): 257-266.
• Pomeroy PP., Twiss SD. & Duck CD. (2000). Expansion of a grey seal (Halichoerus grypus) breeding colony: change in pupping site use at the Isle of May, Scotland. J Zool Lond 250(1): 1-12.
• Twiss SD., Caudron A., Pomeroy PP., Thomas CJ. & Mills JP. (2000). Fine scale topographical influences on the breeding behaviour of female grey seals. Animal Behaviour 59(2): 327-338.
• Worthington-Wilmer J., Overall AJ., Pomeroy PP., Twiss SD. & Amos W. (2000). Patterns of paternal relatedness in British Grey Seal Colonies. Molecular Ecology 9: 283-292.
• Pomeroy PP., Twiss SD. & Redman P. (2000). Philopatry, site fidelity and local kin associations within grey seal breeding colonies. Ethology 106(10): 899-919.
• Twiss SD., Pomeroy PP., Thomas CJ. & Mills JP. (2000). Remote estimation of adult grey seal length, width and body mass from aerial photography - comparison between breeding colonies. Photogrammetric Engineering & Remote Sensing 66(7): 859-866.
• Twiss SD. & Thomas CJ. (1999). Fine scale topographical influences on Environmental Potential for Polygamy (EPP) and male reproductive success in grey seals. European Research on Cetaceans 13: 191-195.
• Worthington-Wilmer J., Allen PJ., Pomeroy PP., Twiss SD. & Amos W. (1999). Where have all the fathers gone? An extensive microsatellite analysis of paternity in the grey seal (Halichoerus grypus). Molecular Ecology 8(9): 1417-1429.
• Standen V., Rees D. & Twiss S. (1998). A palmate newt population in acid bog pools in the Sutherland flows of North Scotland. The Glasgow Naturalist 23(3): 35-39.
• Twiss SD., Anderson SS. & Monaghan P. (1998). Limited intra-specific variation in male grey seal (Halichoerus grypus) dominance relationships in relation to variation in male mating success and female availability. J Zool Lond 246(3): 259-267.
• Mills JP., Newton I. & Twiss SD. (1997). Photogrammetry from archived digital imagery for seal monitoring. Photogram Rec 15(89): 715-724.
• O’Connell MJ., Thomas CJ., Twiss SD., Downie IS., Coulson JC., Evans PR. & Whitfield DP. (1996). Functional ecology of peatland animals in the Flow Country of northern Scotland. I. Habitat requirements of breeding waders (Charadrii). SNH Research, Survey and Monitoring Series 168pp.
• Amos B., Twiss S., Pomeroy P. & Anderson S. (1995). Evidence for mate fidelity in the Gray seal. Science 268(5219): 1897-1899.
• Allen PJ., Amos WA., Pomeroy PP. & Twiss SD. (1995). Microsatellite variation in grey seals (Halichoerus grypus) shows evidence of genetic differentiation between two British breeding colonies. Molecular Ecology 4: 653-662.
• Pomeroy PP., Anderson SS., Twiss SD. & McConnell. (1994). Dispersion and site fidelity of breeding female grey seals (Halichoerus grypus) on North Rona, Scotland. J Zool Lond 233(3): 429-447.
• Twiss SD., Pomeroy PP. & Anderson SS. (1994). Dispersion and site fidelity of breeding male grey seals (Halichoerus grypus) on North Rona, Scotland. J Zool Lond 233(4): 683-693.
• Amos B., Twiss S., Pomeroy P. & Anderson S. (1993). Male mating success and paternity in the grey seal, Halichoerus grypus: a study using DNA fingerprinting. Proc. R. Soc. Lond., B 252: 199-207.

Theses: PhD

• Twiss SD. (1992). Behavioural and energetic determinants of individual mating success in male grey seals (Halichoerus grypus, Fabricius 1791). Zoology Department. University of Glasgow, UK, University of Glasgow, UK. PhD.

Related Links

• Details of Sean's Research & Publications