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Dr. Matt TinsleyLecturer in Evolutionary BiologyPhD -
University of Cambridge (2003) School
of Biological & Environmental Sciences tel: +44 1786 467773 |
PhD studentship opportunities for 2010
Deadline for applications February 26th
Ageing and the invertebrate immune system 
Costly tradeoffs of immune defence
Our research predominantly focuses on the evolutionary ecology of invertebrate host-parasite systems.
Key topics: immune system evolution, Drosophila, genetic variation in pathogen defence, host-parasite coevolution, senescence, insect sex ratios, parthenogenesis, Wolbachia, male-killing bacteria, ladybirds.
The immune system and ageing
Our work on immune systems and ageing investigates two interrelated and complimentary questions. First, how does pathogen defence change as animals age? Second, how does activity of the immune system influence the rate of senescence in other traits and affect lifespan?
As animals age many physiological systems deteriorate. This process of senescence has a strong impact on the immune system; in humans the incidence of infectious disease increases markedly in the aged fraction of the population. We are studying immune system senescence in Drosophila. We have characterised how disease resistance changes with age and are identifying genetic tradeoffs which may influence immune senescence rate. Danielle Mackenzie’s PhD project is investigating the Drosophila cellular immune response. She focuses on plasmatoctyes, which play a significant role in pathogen defence in adult flies. Danielle’s work has revealed that as flies age the number of circulating plasmatocytes decreases and their ability to phagocytose pathogen particles declines.
We have also investigated how the ability to mount an immune response influences the pattern of ageing in fly populations. We assess ageing by calculating the rate at which the population mortality rate increases as its individuals become older: as individuals get older they become increasingly likely to die. Our results demonstrate that blocking the major immune signalling pathways in the fly (Toll and IMD pathways) slows the rate of senescence. We are currently investigating the factors underlying this effect.
Genetic variation in immune traits
Within any animal population some individuals suffer morbidity and mortality from infectious disease, whilst others effectively resist attack from pathogens and parasites. We seek to understand why this is so, both at the level of the organism’s immune physiology and the genes underlying these traits. Our work centres on Drosophila and the fungal pathogen Beauveria bassiana. Recent findings demonstrate that considerable genetic variation exists within Drosophila populations for traits determining immune defence and that selection has driven significant divergence in pathogen susceptibility between different worldwide populations. We have gone on to identify several regions within the Drosophila genome that influence pathogen susceptibility and are in the process of identifying the genes responsible. This work not only answers fundamental questions regarding the evolution and ecology of insect infectious disease, but also, by working in a model system such as Drosophila, our data have close relevance for applied issues relating to insect vectored disease, biological control and human health.
Ecology of bumblebee disease
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There is considerable current concern about the conservation status of pollinator populations in the UK and worldwide. One factor which has contributed to global declines in pollinator abundance is disease. We are particularly interested in the viral infections of bumblebees and honeybees; we seek to identify factors determining their prevalence and transmission in natural populations. Penelope Whitehorn's PhD is investigating the impact of inbreeding on disease susceptibility and other fitness traits in bumblebees. She has recently demonstrated that inbreeding has a very considerable impact on bumblebee nest survival in the field and that bumblebee queens attempt to avoid mating with closely related males. Penelope’s current work involves fieldwork on the Hebridean islands, investigating how the genetic diversity of wild bumblebee populations influences pathogen prevalence and immune function.
The threatened great yellow bumblebee. Note the small phoretic mite attached to the rear leg. Photo by Nick Owens. |
Reproductive behaviour, parthenogenesis and sex ratio distortion in arctic insects
The Greenlandic Seed Bug |
 Bug collecting on moss campion |
Mountains of east |
The reason why the vast majority of animals reproduce sexually is one of the most debated topics in evolutionary biology. When a parent produces offspring sexually it faces the major cost that it is only related to its progeny by 50%. In contrast an asexual parent avoids these costs, being 100% related to its offspring. Explanations for the prevalence of sex as a reproductive strategy focus mainly on the rapidity of evolutionary adaptation in sexual populations and their ability to avoid some damaging effects of harmful mutations. The Greenlandic Seed Bug (Nysius groenlandicus) displays variable reproductive behaviour around Greenland, with some populations reproducing sexually and others asexually. This species therefore provides a useful test case for comparisons of sexual and asexual strategies. To further complicate the matter, some individuals within populations of this species are infected by a bacterial parasite Wolbachia, which can alter a variety of aspects of host reproduction. Current work is investigating this insect’s reproductive behaviour and studying the effects of its inherited bacterial parasites.
Related work
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In other recent work I have studied the ecological and evolutionary dynamics of sex ratio distorting bacterial infections in ladybirds. These parasites are not conventionally infectious but are transmitted maternally to offspring (within the egg). As it is only females that provide a means of transmission, such parasites have evolved a variety of mechanisms to bias the offspring sex ratio that hosts produce in favour of females. One class of bacteria, termed male-killers, kill the male offspring of infected females before they hatch from the egg. My investigations have focussed on explaining between-population prevalence variation in male-killing infections, their long-term evolutionary dynamics and studying the evolutionary potential for these parasites to shift between host species. In addition our research has investigated the sexually transmitted mite Coccipolipus hippodamiae that infects two spot ladybirds and can cause partial or full sterility in many continental European populations.
Collaborators
Frank Jiggins’ Group (Cambridge)
Luc Bussiere’s Group (Stirling)
Mike Williams' Group (Aberdeen)
Recent Publications
Whitehorn, P. R., Tinsley, M. C. and Goulson, D. (2009) Kin recognition and inbreeding reluctance in bumblebees. Apidologie. 40, 627-633.
Goulson D., McGuire K., Munro E. E., Adamson S., Colliar L., Park K. J., Tinsley M.C. & Gilburn A. (2009) Functional significance of the dark central floret of Daucus carota (Apiaceae) L.; is it an insect mimic? Plant Species Biology. 24, 77-82.
Whitehorn, P. R., Tinsley, M. C., Brown, M. J. F., Darvill, B., and Goulson, D. (2009) Impacts of inbreeding on bumblebee colony fitness under field conditions. BMC Evolutionary Biology. 9, 152.
Tinsley, M. C. and Majerus, M.E.N. (2007) Small steps or giant leaps for male-killers? Phylogenetic constraints to male-killer host shifts. BMC Evolutionary Biology. 7, 238.
Weinert, L. A., Tinsley, M. C., Temperley, M. and Jiggins, F. M. (2007) Are we underestimating the diversity and incidence of insect bacterial symbionts? A case study in ladybird beetles. Biology Letters. 3, 678–681.
Goulson, D., Cruise, J. L., Sparrow, K. R., Harris, A. J., Park, K. J., Tinsley, M. C. and Gilburn, A. S. (2007) Choosing rewarding flowers; perceptual limitations and innate preferences influence decision making in bumblebees and honeybees. Behavioral Ecology and Sociobiology. 61, 523–1529.
Tinsley, M.C., Blanford, S. and Jiggins, F.M. (2006) Genetic variation in Drosophila melanogaster pathogen susceptibility. Parasitology. 132, 767-773.
Tinsley, M.C. and Majerus, M.E.N. (2006) A new male-killing parasitism: Spiroplasma bacteria infect the ladybird Anisosticta novemdecimpunctata (Coleoptera: Coccinellidae). Parasitology. 132, 757-765.
Webberley, K.M., Tinsley, M.C., Sloggett, J.J., Majerus, M.E.N., and Hurst, G.D.D. (2006) Spatial variation in the incidence of sexually transmitted parasites of the ladybird beetle Adalia bipunctata. European Journal of Entomology. 103, 793-797.
Jiggins F.M. and Tinsley, M.C. (2005) An ancient mitochondrial polymorphism in Adalia bipunctata linked to a sex ratio distorting bacterium. Genetics. 171, 1115-1124.
Tinsley, M.C., and Reilly S.D. (2002) Reproductive ecology of the saltmarsh-dwelling marine ectoparasite Paragnathia formica (Crustacea: Isopoda). Journal of the Marine Biological Association of the United Kingdom, 82, 79-84.
Linskens, H. F. and Tinsley, M.C. (2002) Pollen deposition in moss polsters from Northeast Greenland. Circumpolar Journal, 17, 17-24.
