Ghazoul, J. (2006) Floral diversity and the facilitation of
pollination.Journal of Ecology, 94 , 295–304.
Gomez, J.M., Bosch, J., Perfectti, F.,et al. (2007) Pollinator
diversity affects plant reproduction and recruitment:
the tradeoffs of generalization.Oecologia, 153 , 597–605.
Grime, J.P., Mackey, J.M.L., Hillier, S.H. and Read, D.J.
(1987) Floristic diversity in a model system using exper-
imental microcosms.Nature, 328 , 420–2.
Gutschick, V.P. (1981) Evolved strategies in nitrogen acquisi-
tion by plants.The American Naturalist, 118 , 607–37.
Hagen, M.J. and Hamerick, J.L. (1996) Population level
processes inRhizobium leguminosarumbvtrifolii: the
role of founder effects.Molecular Ecology, 5 , 707–14.
Hardin, G. (1968) Tragedy of commons.Science, 162 ,
1243–8.
Hartnett, D.C. and Wilson, W.T. (1999) Mycorrhizae influ-
ence plant community structure and diversity in tall
grass prairie.Ecology, 80 , 1187–95.
Hay, M.E., Parker, J.D., Burkepile, D.E.,et al. (2004) Mu-
tualisms and aquatic community structure: the enemy
of my enemy is my friend.Annual Review of Ecology and
Systematics, 35 , 175–97.
Helgason, T., Daniell, T.J., Husband, R.,et al. (1998)
Ploughing up the wood-wide web.Nature, 394 , 431.
Helgason, T., Merryweather, J.W., Young, J.P.W. and Fit-
ter, A.H. (2007) Specificity and resilience in the arbus-
cular mycorrhizal fungi of a natural woodland
community.Journal of Ecology, 95 , 623–30.
Hempel,S.,Renker,C.andBuscot,F.(2007)Differencesinthe
species composition of arbuscular mycorrhizal fungi in
spore, in a grassland ecosystem root and soil communities.
Environmental Microbiology, 9 , 1930–8.
Herre, E.A., Knowlton, N., Mueller, U.G. and Rehner, S.A.
(1999) The evolution of mutualisms exploring the paths
between conflict and cooperation.Trends in Ecology &
Evolution, 14 , 49–53.
Hetrick, B.A.D., Wilson, G.W.T. and Hartnett, D.C. (1989)
Relationships between mycorrhizal dependency and
competitive ability of two tall grass prairie forbs.Cana-
dian Journal of Botany, 70 , 1521–8.
Heywood, V.H., ed. (1993)FloweringPlants of the World.
Oxford University Press, New York, NY.
Hoeksema, J.D. and Bruna, E.M. (2000) Pursuing the big
questions about interspecific mutualism: a review of
theoretical approaches.Oecologia, 125 , 321–30.
Hoeksema, J.D. and Schwartz, M.W. (2003) Expanding
comparative-advantage biological market models: con-
tingency of mutualism on partners’ resource require-
ments and acquisition trade-offs. Proceedings of the
Royal Society of London B, 270 , 913–19.
Hoeksema, J.D. and Schwartz, M.W. (2006) Modeling in-
terspecific mutualisms as biological markets. InEconom-
ics in Nature(eds R. Noe ̈, J.A.R.A.M. van Hooff and P.
Hammerstein). Cambridge University Press, Cam-
bridge.
Holland, J.N., DeAngelis, D.L. and Schultz, S.T. (2004)
Evolutionary stability of mutualism: interspecific popu-
lation regulation as an evolutionarily stable strategy.
Proceedings of Royal Society of London B, 271 , 1807–14.
Horton, T.R. and van der Heijden, M.G.A. (2008) The role
of symbioses in seedling establishment and survival. In
Seedling Ecology and Evolution(eds M. Leck, V.T. Parker
and B. Simpson). Cambridge University Press, Cam-
bridge.
James, T.Y., Kauff, F., Schoch, C.L.,et al. (2006) Recon-
structing the early evolution of fungi using a six-gene
phylogeny.Nature, 443 , 818–22.
Johnson, N.C., Graham, J.H. and Smith, F.A. (1997) Func-
tioning of mycorrhizal associations along the mutualism–
parasitism continuum.New Phytologist, 135 ,575–85.
Johnson, S.D., Peter, C.I., Nilsson, L.A. and Agren, J. (2003)
Pollination success in a deceptive orchid is enhanced by
co-occurring rewarding magnet plants. Ecology, 84 ,
2919–27.
Kato, M., Takimura, A. and Kawakita, A. (2003) An obli-
gate pollination mutualism and reciprocal diversifica-
tion in the tree genus Glochidion (Euphorbiaceae).
Proceedings of the National Academy of Sciences of the
United States of America, 100 , 5264–7.
Kawakita, A. and Kato, M. (2004) Evolution of obligate
pollination mutualism in New CaledonianPhyllanthus
(Euphorbiaceae).American Journal of Botany, 91 , 410–15.
Kearns, C.A., Inouye, D.W. and Waser, N.M. (1998)
Endangered mutualisms: the conservation of plant pol-
linator interactions.Annual Review of Ecology and System-
atics, 29 , 83–112.
Kiers, E.T. and Denison, R.F. (2008) Sanctions, cooperation,
and the stability of plant-rhizosphere mutualisms.Annual
Review of Ecology, Evolution and Systematics, 39 , 215–36.
Kiers, E.T. and van der Heijden, M.G.A. (2006) Mutualistic
stability in the arbuscular mycorrhizal symbiosis: ex-
ploring hypotheses of evolutionary cooperation.Ecolo-
gy, 87 ,1627–36.
Kiers, E.T., West, S.A. and Denison, R.F. (2002) Mediating
mutualisms: farm management practices and evolution-
ary changes in symbiont co-operation.Journal of Applied
Ecology, 39 , 745–54.
Kiers, E.T., Rousseau, R.A., West, S.A. and Denison, R.F.
(2003) Host sanctions and the legume–rhizobium mutu-
alism.Nature, 425 , 78–81.
Kiers,E.T.,Rousseau,R.A.andDenison,R.F.(2006)
Measured sanctions: legume hosts detect quantitative var-
iation in rhizobium cooperation and punish accordingly.
Evolutionary Ecology Research, 8 , 1077–86.
REFERENCES 239