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The case of the one-eyed brine shrimp : are ancient atavisms possible?

Fryer, Geoffrey (1999) The case of the one-eyed brine shrimp : are ancient atavisms possible? Journal of Natural History, 33 (6). pp. 791-798. ISSN 0022-2933

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Abstract

In the cyclopean mutant of the anostracan branchiopod Artemia franciscana, paired stalked eyes are replaced by a single, median, sessile, eye resembling that found in certain monocular branchiopod orders. This eye, its nerve supply, and skeletal support, comprise a perfect unit which appears to be a spontaneous atavism. However, according to recent calculations this cannot be so. These suggest that while re-activation of long-silent genes, on which atavisms depend, can occur after a lapse of up to 6 million years (My), this is impossible after 10 My unless the gene is maintained by active selection, which cannot apply here. However, the Anostraca is an old group, and the atavism (if such it be) is clearly very ancient. Efficient DNA repair, not considered in the calculations, offers a possible explanation of how silent genes may survive for longer than the suggested period of viability. Particularly intriguing is that a binocular condition is primitive and the cyclopean derived, which has remarkable evolutionary implications. It suggests two reversals during the history of the Anostraca from paired sessile eyes to a long-extinct monocular condition such as prevails in certain other branchiopods, later to paired stalked eyes. Other ancient atavisms also challenge the claim that silent genes have short life spans. This problem, which has fundamental biological implications, is still sub-judice.

Item Type: Article
Journal or Publication Title: Journal of Natural History
Uncontrolled Keywords: Cyclopean ; Artemia ; Ancient Atavisms ; Silent Genes
Subjects: Q Science > QH Natural history > QH301 Biology
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 10933
Deposited By: Mr Richard Ingham
Deposited On: 28 Jul 2008 11:36
Refereed?: Yes
Published?: Published
Last Modified: 18 Sep 2013 16:01
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/10933

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