Genetic polymorphism as evidence of outbreeding in graptoloids

Article (within a thematic volume) 13 Tue, 01/01/1974 - 12:00 Graptolite studies in honour of O. M. B. Bulman R. B. Rickards, D. E. Jackson and C. P. Hughes 15 18

URBANEK, A., JAANUSSON, V. 1974. Genetic polymorphism as evidence of outbreeding in graptoloids. In RICKARDS, R. B., JACKSON, D. E., HUGHES, N. F. (eds.). Graptolite studies in honour of O. M. B. Bulman. Special Papers in Palaeontology, 13, pp. 15–18.

Adam Urbanek and Valdar Jaanusson

Since graptoloids occupied a relatively stable and little differentiated pelagic biotope, numerous instances of genetic polymorphism within their species may be considered as indirect evidence of outbreeding as the mode of their reproduction. Under such conditions genetic polymorphism could be maintained mainly as a result of the heterotic effect, and outcrossing is the only way to provide the requisite heterozygosity.

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