Partial reproductive incompatibility between populations of spider mites (acarina: tetranychidae)
1976
OVERMEER, W.P.J. | ZON, A.Q.
Partial reproductive incompatibility between spider mite populations of different origin is a common phenomenon. A comparative study was made of the characteristics of partial reproductive incompatibility both between various natural populations of Tetranychus urticae and between a laboratory strain and a number of chromosome mutation homozygous strains derived from it. Interpopulation crossing experiments were set up and percentages of nonviability assessed in the F₁, the haploid F₂, the B₁ obtained from hybrids that had been mated with males of the original male parent stock and the B₁ produced by hybrids that had been mated by males of the original female parent stock. In those cases where partial reproductive incompartibility between populations is due to different chromosome mutations similar degrees of nonviability were observed for the haploid F₂ and the B₁ generations belonging to it. With natural reproductive incompatibility the degree of lethality was highest in the haploid F₂; the percentage nonviability was usually less for fertilized eggs, and especially when the eggs were fertilized by a gamete of a male of the same origin as the female parent of the hybrid. Differences in hybrid sterility between reciprocal crosses were often found. It is assumed that, although chromosome mutations may play a role in speciation of tetranychids, partial reproductive incompatibility between natural populations is mainly due to lethal recombinations of genes and interactions between cytoplasmic factors and genes of “alien” male gametes.
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