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Sex and outcrossing in a sessile freshwater invertebrate

Freeland, J. R., Lodge, R. J. and Okamura, B. (2003) Sex and outcrossing in a sessile freshwater invertebrate. Freshwater Biology, 48 (2). pp. 301-305. ISSN 0046-5070

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To link to this item DOI: 10.1046/j.1365-2427.2003.00996.x

Abstract/Summary

1. The freshwater bryozoan Cristatella mucedo, in common with other sessile, benthic freshwater taxa, has an unusual life history: sex occurs during a relatively brief period near the start of the growing season, and overwintering occurs in the form of asexually produced dormant propagules (statoblasts). Consistent observed heterozygosity (Ho) deficits in C. mucedo populations have previously suggested that inbreeding is common, although a possible contribution of a Wahlund effect to low Ho could not be discounted. 2. We have used microsatellite data in the first study based on codominant markers to genetically characterise maternal colonies and larval offspring of C. mucedo . The 'population' represented by the larvae was in Hardy-Weinberg equilibrium, which has previously been found in only one of 39 populations of C. mucedo . At least 64% of larvae were the products of outcrossing. We suggest that the unusual early timing of sex may be a strategy to maximise rates of outcrossing within populations of sessile freshwater invertebrates.

Item Type:Article
Refereed:Yes
Divisions:Faculty of Life Sciences > School of Biological Sciences
ID Code:10741
Uncontrolled Keywords:freshwater bryozoan, life history, observed heterozygosity, outcrossing, Wahlund effect, BRYOZOAN CRISTATELLA-MUCEDO, WATER BRYOZOAN, GENETIC DIVERSITY, POPULATIONS, MICROSATELLITE, FLOW

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