The Journal of Heredity 1996:87(1):41-47
© 1996 The American Genetic Association 87:41-47
research-article |
Gene Flow in Colonizing Hippodamia variegata Ladybird Beetle Populations
From the Department of Entomology, Iowa State University Ames, lA 50011
Address reprint requests to Dr. E. S. Krafsur at the address above.
Corresponding Editor: Robert C. Vrijenhoek
Abstract
Genetic diversity and gene flow at allozyme loci was investigated in natural and laboratory-reared populations of the predatory ladybird species Hippodamia variegata, a recently naturalized beetle from the Palaearctic. Gene diversity was 24.9 ± 4.9% at 28 resolved loci and 31.6 ± 5.5% at 22 polymorphic loci. Average gene diversity at nine polymorphic loci was only slightly greater among field-collected beetles than among laboratory-cultured beetles. There were five alleles in cultured beetles not found in natural U.S. population samples. Wright's F statistics showed modest genetic differentiation among two field collections from the northeastern United States and one from Europe (FST = 0.107 ± 0.077). Analysis of variance in gene frequencies in these feral ladybirds showed that about 97% of the variance existed within populations of this colonizing species. A substantial level of genetic differentiation was detected among 10 laboratory populations descended from col lections made in Europe, Asia, North Africa, and Chile (FST = 0.191 ± 0.021). Drift is the most likely explanation for this differentiation.