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- Title
Increase in developmental instability upon inbreeding in Daphnia.
- Authors
DENG, HONG-WEN
- Abstract
Lerner's genetic homeostasis theory (1954) hypothesizes that developmental instability (DI) will be higher for individuals with lower genomic heterozygosity. Because the usual indices of DI may confound genetic effects with random developmental process, most previous tests of the hypothesis may have explanational difficulties. I shall present an alternative approach to test the genetic homeostasis hypothesis. In this approach, outcrossed and inbred genotypes, each having multiple clonal replicates, are assayed side-by-side in one controlled homogeneous and benign environment. Phenotypic variation among replicates for each genotype is used as a relative index for DI, not confounded by any possible genetic effect. The outcrossed genotypes differ from the inbred ones in the average genomic heterozygosity, thus avoiding the ambiguity of using heterozygosity at the allozyme level as an index for that at the genomic level. The approach may also provide data on the potential effects of genotypic value (G) on DI. The results of experiments on two cyclically parthenogenetic Daphnia species (D. pulex and D. pulicaria) reveal that (i) for all characters analysed, DI increases upon inbreeding and (ii) there is no significant relationship between G and DI. The increase in DI upon inbreeding is thus attributable only to a reduction in heterozygosity (per se or an enhanced expression of deleterious recessive alleles). Therefore, the present study is consistent with Lerner's genetic homeostasis hypothesis.
- Subjects
DAPHNIA; GENETICS; INBREEDING
- Publication
Heredity, 1997, Vol 78, Issue 2, p182
- ISSN
0018-067X
- Publication type
Article
- DOI
10.1038/hdy.1997.26