Duur Aanen

Duur1.jpg

Duur K. Aanen

Postal adress:

Laboratory of Genetics
Wageningen University
Droevendaalsesteeg 1
6708 PB
Wageningen
The Netherlands

Telephone: (+) 31 317 482706
Fax:(+) 31 317 483146

Email: duur.aanen@wur.nl

The evolution of cooperation

Cooperation occurs at all levels of biological organization: from organelles within a single cell to mutualism between different species. My research focuses on the evolution of stable cooperation despite potential conflicts of interest between partners. We employ theoretical, phylogenetic (pp on Bayesian analysis) and experimental approaches, using fungi as model organisms. Our focus is on cooperation at three different hierarchical levels of biological organization:

  1. Between species in a mutualism (fungus-growing termites and fungi);
  2. Between individuals within a species (somatic fusion between fungal individuals);
  3. Between organelles (nuclei and mitochondria) within the mycelium of fungi.

Within this research theme, there are several possibilities for MSc projects (Thesis topics).

1. The evolution of the symbiosis between termites and fungi

Termites of the old world subfamily Macrotermitinae live in a mutualistic symbiosis with fungi of the genus Termitomyces (basidiomycetes). These fungus-growing termites cultivate their fungus for food inside their nests, probably in single-strain monocultures, on a substrate of finely comminuted plant material. Phylogenetic studies have shown that there has only been a single transition to agriculture in termites, involving the domestication of a single fungal lineage.

Fungus-growing termites of the species Macrotermes bellicosus tending and harvesting their fungal crops (photo courtesy of Prof. Renoux).
Fungus-growing termites of the species Macrotermes bellicosus tending and harvesting their fungal crops (photo courtesy of Prof. Renoux).

Current research focuses on:

i). conflicts of interest between the mutualistic partners. Despite obligate reciprocal dependence of the two partners in this mutualism, their interests are not identical. For example, since reproduction occurs independently in most species, there is a conflict of interest over the resources that ultimately go to fungal reproduction and to insect reproduction.How are conflicts of interest resolved? MC fellow Tânia Nobre studies how transmission modes of the fungi have affected the colonization of Madagascar by fungus-growing termites and their fungal symbionts (collaboration with Dr. Paul Eggleton).

ii). ‘Disease management’ of termite farmers. The fungus garden is continuously exposed to biotic threats, in the form of general soil organisms, and –possibly– specialized parasites and weeds. However, termites are apparently able to keep their agriculture free of disease. PhD student  Anna Visser focuses on the diseases and weeds of the fungus gardens and the way termites are able to suppress those.

2. The social evolution of somatic fusion in fungi

 In fungi, somatic fusion can occur between different individuals (mycelia). Somatic fusion is a social process: it can have consequences for both fusing partners. In fungi, fusion is usually restricted to close kin. However, some theoretical models suggest that genetic kin recognition is not evolutionarily stable. We study how this discrepancy can be explained, and under what circumstances kin-based conditional fusion can evolve. Within this theme, I have funding for a PhD position (4 years).

3. Intragenomic conflicts within mushroom-forming basidiomycetes

Basidiomycete fungi are unique because somatic fusion forms a regular part of their life cycle, which leads to genetic mosaics of various types (nuclear, cytoplasmic) at various levels (Fig. 2). This creates potential conflicts between different levels of selection. PhD student Bart Nieuwenhuis studies this subject in the project 'Nuclear tests in mushrooms', using the species Schizophyllum commune as a model species. 

The standard life cycle of a heterothallic basidiomycete fungus. Sexual spores germinate (upper left) and give rise to a haploid monokaryon. Two compatible monokaryons can fuse upon which they reciprocally exchange nuclei, without cytoplasmic mixing (down right). This leads to the formation of the dikaryon (right), all cells of which have two different nuclei, and which is a cytoplasmic mosaic. The dikaryon can produce mushrooms, the sexual fruiting bodies, where a short diploid stage is immediately followed by meiosis and sexual spore formation. The insert shows how the two nuclei in a dikaryotic cell are distributed over cells during cell division via the formation of clamp connections.
The standard life cycle of a heterothallic basidiomycete fungus. Sexual spores germinate (upper left) and give rise to a haploid monokaryon. Two compatible monokaryons can fuse upon which they reciprocally exchange nuclei, without cytoplasmic mixing (down right). This leads to the formation of the dikaryon (right), all cells of which have two different nuclei, and which is a cytoplasmic mosaic. The dikaryon can produce mushrooms, the sexual fruiting bodies, where a short diploid stage is immediately followed by meiosis and sexual spore formation. The insert shows how the two nuclei in a dikaryotic cell are distributed over cells during cell division via the formation of clamp connections.

Selected publications

  • Aanen, D.K., H.H. De Fine Licht, A.J.M. Debets, N.G. Kerstes, R.F. Hoekstra & J.J. Boomsma (2009) High symbiont relatedness stabilizes mutualistic cooperation in fungus-growing termites. Science, 326(5956):1103-1106
  • Nobre, T.M., P. Eggleton & D.K. Aanen (2010) Vertical transmission as the key to the colonization of Madagascar by fungus-growing termites? Proc. R. Soc. London B. 277:359-365.
  • Boomsma, J.J. & D.K. Aanen (2009) Rethinking crop-disease management in fungus-growing ants.Proceedings of the National Academy of Sciences of the USA, 106, 17611-17612.
  • Bijma, P. & D.K. Aanen (2009) Assortment, Hamilton's rule and group selection.Proc. R. Soc. London B. in press
  • Harder, C.B. & D.K. Aanen (2009) Unilateral nuclear migration in Basidiomycetes: pheromone interaction, genomic conflict and mating-system reversion. Fungal Biology Reviews in press.
  • Aanen, D.K., B. Slippers & M.J. Wingfield (2009) Biological pest control in beetle agriculture. Trends in Microbiology 17: 179-182.
  • Visser, A.A., V.I.D. Ros, Z.W. de Beer, A.J.M. Debets, E. Hartog, T.W. Kuyper, T. Læssøe, B. Slippers and D.K. Aanen (2009) Levels of specificity of Xylaria species associated with fungus-growing termites: a phylogenetic approach. Molecular Ecology 18: 553-567.
  • Aanen, D.K., A.J.M. Debets, J.A.G.M. de Visser & R.F. Hoekstra (2008) The social evolution of somatic fusion. Bioessays, accepted for publication.
  • Aanen, D.K. (2008) Using the 'Buller phenomenon' in experimental evolution studies of basidiomycetes. Fungal Genetics Reports 55, 13-14. pdf
  • Aanen, D.K. & R.F. Hoekstra (2007) The evolution of obligate mutualism: if you can’t beat ‘em, join ‘em. Trends Ecol. Evol. 22, 506-509. pdf
  • Aanen, D.K., V.I.D. Ros, H.H. de Fine Licht, J. Mitchell, Z.W. de Beer, B. Slippers, C. Rouland-Lefèvre & J.J. Boomsma (2007) Patterns of interaction specificity of fungus-growing termites and Termitomyces symbionts in South Africa. BMC Evolutionary Biology. 7, 115-125. pdf
  • Aanen, D.K. and R.F. Hoekstra (2007) Why sex is good: on fungi and beyond. In: Sex in fungi: molecular determination and evolutionary implications (ed. Heitman, J., J. Kronstad, J.W. Taylor and L. Casselton)
  • Aanen, D.K. and J.J. Boomsma (2006) Social insect fungus farming. Current Biology 16, R1014-R1016. pdf
  • De Fine Licht, H.H., J.J. Boomsma and D.K. Aanen (2006) Presumptive horizontal symbiont transmission in the fungus-growing termite Macrotermes natalensis. Molecular Ecology, 3131-3138. pdf
  • Aanen, D.K. (2006) As you reap, so shall you sow: coupling of harvesting and inoculating stabilises the mutualism between termites and fungi. Biology Letters 2, 209 - 212. pdf
  • Aanen, D.K. and P. Eggleton (2005) Fungus-growing termites evolved in African rain forest. Current Biology 15, 851-855. pdf
  • Mueller, U.G., Schultz, T.R., Aanen, D.K., Six, D. and Gerardo N. (2005). The evolution of agriculture in insects. Ann. Rev. Ecol. Evol. Syst., 36, 563-595. pdf
  • Aanen, D.K., Th.W. Kuyper, A.J.M. Debets and R.F. Hoekstra (2004). The evolution of non-reciprocal nuclear exchange in mushrooms as a consequence of genomic conflict. Proc. R. Soc. Lond. B. 271: 1235–1241. pdf
  • Korb J. and D.K. Aanen (2003). The evolution of uniparental transmission of fungal symbionts in fungus-growing termites (Macrotermitinae). Behav. Ecol. Sociobiol. 53, 65-71. pdf
  • Aanen, D.K., P. Eggleton, C. Rouland-Lefèvre, T. Guldberg-Frøslev, S. Rosendahl and J.J. Boomsma (2002). The evolution of fungus-growing termites and their mutualistic fungal symbionts. Proceedings of the National Academy of Sciences of the USA, 99, 14887-14992. pdf
  • Aanen, D.K., Th.W. Kuyper, T.H.M. Mes and R.F. Hoekstra (2000). The evolution of reproductive isolation in the ectomycorrhizal Hebeloma crustuliniforme aggregate (Basidiomycetes) in northwestern Europe: a phylogenetic approach. Evolution 54, 1192-1206. pdf

Full list of publications


Popular-science publications

  • Aanen, D.K. and Z. W. de Beer (2007) Farming fungi. Termites show the way. Quest (South Africa) 3(3): 22-25 pdf
  • Aanen, D.K. (2005) Termitter som landmœnd. Aktuel Naturvidenskab 5: 16-18 pdf
  • Aanen D.K. (2003). Small farmers. Invited ‘letter to the editor’ Nat. Hist. 112 (6): 13
  • Aanen, D. K. (2001). Soorten en soortvorming in het Hebeloma crustuliniforme-complex. Coolia 44(4), 197-207

Biography:

Education 

  • 1989 - 1994 MSc Biology, Utrecht University
  • 1994 - 1999 PhD Genetics, Wageningen University  

Professional 

  • 1999-2000 Lecturer at Department of Genetics of Wageningen University, The Netherlands
  • 2000-2004 Postdoc (Dept. Population Ecology, Zoological Institute, University of Copenhagen)
  • 2004-2005 Assistant research professor (Dept. Population Biology, Institute of Biology, University of Copenhagen
  • 2005-2006 Associate professor (Dept. Population Biology, Institute of Biology, University of Copenhagen
  • 2006-2007 ‘speerpunt’ postdoc (Laboratory of Genetics, Wageningen University)
  • 2008-present: assistant professor (Laboratory of Genetics, Wageningen University)

Grants

  • EU Marie Curie postdoctoral fellowship (2 years, 2000)
  • STENO fellowship (3 years; Danish National Research Council, FNU, 2004)
  • ‘Speerpunt’ postdoc grant (Graduate School PE&RC, 3+2 years, including money for PhD student; 2005)
  • ALW open competition PhD proposal ‘Nuclear tests in mushrooms’ (2006)
  • VIDI (2007)

Media

  • Bionieuws (Dutch magazine for biologists, 16 February 2008) Volmaakt afhankelijk.
  • The New York Times (USA, 15 October, 2002): ‘Before Adam and Eve, the Farmers Were Termites’ (full-page article on occasion of PNAS article) (link)
  • NRC-Handelsblad (Dutch newspaper, 19 October, 2002): ‘Termietenlandbouw evolueerde slechts een keer en onomkeerbaar’.
  • Trouw (Dutch newspaper, 6 November 2002): ‘Enkele reis afvalkamer’
  • Berlingske Tidende (Danish newspaper, 6 November 2002): ’Verdens første svampefarmere’
  • Illusteret Videnskab (Danish popular science magazine, July 2003): ’Termitter var Afrikas første farmere’
  • NRC-Handelsblad (Dutch newspaper, 14 May 2005). Termieten veroverden de droge savanne met woudschimmel.
  • De Volkskrant (Dutch newspaper, April 14 2007): ‘Bij de mier exploiteert het gewas ook de boer’
  • Radio:
  • Interview in Principia (Danish radio, 15 March 2003): ’At leve i symbiose med planter’ (link)

Collaborations

  • Jim Anderson (University of Toronto, Canada)
  • Johan Baars (PRI, Wageningen University and Research Center)
  • Wilhelm de Beer (FABI, University of Pretoria, South Africa)
  • Koos Boomsma (Center of Social Evolution, University of Copenhagen, Denmark)
  • Paul Eggleton (Natural History Museum, London)
  • Henrik Hjarvard de Fine Licht (Center of Social Evolution, University of Copenhagen, Denmark)
  • Judith Korb (University of Regensburg, Germany)
  • Thomas Kuyper (University of Wageningen, Netherlands)
  • Luis Lugones (Utrecht University, Netherlands)
  • Thomas Lœssøe (University of Copenhagen, Denmark)
  • Jannette Mitchell (Pretoria, South Africa)
  • Corinne Rouland-Lefèvre (IRD, France)
  • Bernard Slippers (FABI, University of Pretoria, South Africa)
  • Anton Sonnenberg (PRI, Wageningen University and Research Center)
  • Vivienne Uys (PPRI, Pretoria, South Africa)
  • Mike Wingfield (FABI, University of Pretoria, South Africa)
  • Han Wösten (Utrecht University, Netherlands)