Content area
Full Text
letters to nature
20. Young, G. C. in Palaeozoic Vertebrate Biostratigraphy and Biogeography (ed. Long, J. A.) 208251 (Belhaven, London, 1993).
21. Vorobyeva, E. I. & Schultze, H.-P. in Origins of the Higher Groups of Tetrapods: Controversy and Consensus (eds Schultze, H.-P. & Trueb, L.) 68109 (Cornell Univ., Ithaca, NY, 1991).
22. Schultze, H.-P. & Arsenault, M. The panderichthyid sh Elpistostege: a close relative of tetrapods? Paleontology 28, 293309 (1985).
23. Schultze, H.-P. Dipnoans as sarcopterygians. J. Morphol. 1 (suppl.), 3974 (1986).24. Clack, J. A. Acanthostega gunnari, a Devonian tetrapod from Greenland; the snout, palate and ventral parts of the braincase, with a discussion of their signicance. Meddr. Grnland Geoscience 31, 124 (1994).
Supplementary information is available on Natures World-Wide Web site (http://www.nature.com) or as paper copy from the London editorial ofce of Nature.
Acknowledgements. We thank the Australian Museum for their award of a Visiting Fellowship to P.E.A.A. Ritchie for inviting us to work on the Canowindra material and J. Long and J. Jeffery for discussions and access to rhizodont material. Z.J. thanks J. Fairfax for nancial support. This Letter is dedicated to the memory of S. M. Andrews.
8
Selsh genes: a green beard in the red re ant
Laurent Keller* & Kenneth G. Ross * Institute of Zoology and Animal Ecology, University of Lausanne, Btiment de Biologie, 1015 Lausanne, Switzerland Department of Entomology, University of Georgia, Athens, Georgia 30602-2603, USA
Table 1 Proportion of young queens of each Gp-9 genotype attacked by workers
Proportion of queens attacked
Age Gp-9 genotype.............................................................................................................................................................................
BB Bb bb
710 days 0.61 0.00 0.00 (n 19 colonies) (n 90) (n 275) (n 5)
1114 days 0.91 0.00 0.00 (n 18 colonies) (n 11) (n 327) (n 11).............................................................................................................................................................................The frequencies of attacks on 710-day-old queens varied signicantly according to genotype (G 190:78; d:f: 2; P [H11021] 0:0001). The proportion of BB queens attacked was signicantly greater than the proportion of either Bb queens (G 189:16; d:f: 1; P [H11021] 0:0001) or bb queens (G 9:04; d:f: 1; P 0:003) attacked (the few bb queens found presumably had not yet succumbed to the age-dependent lethal effects of this genotype ). The same pattern was revealed within individual colonies: in each of the 16 colonies in which BB queens were present, the...