Population Biology and the Tribolium Model

SUMMARYPrevious results demonstrated that modification of the genetic background producea changes in the fitness of genotypes at the diazinon resistance locus in Lucilia cuprina (McKenzie eta!., 1982). Fitness sets were estimated from population cage studies following disruption of the field genome by generations of backcrossing of a resistant field strain to males of a susceptible laboratory strain.The present experiments report the results of a similar procedure where females of the laboratory strain have been used as the recurrent backcross parent. In this case recombination between the field and laboratory genomes is precluded during backcrossing. Population cage results were analogous to those of the previous experiments suggesting fitness modifiers were unlinked to the diazinon resistance locus on chromosome IV. The use of chromosome substitution lines provided confirmation. Major fitness modifiers were mapped to chromosome III.The relevance of changes in the fitness sets of insecticide resistance genotypes, because of genetic background modification, to models of the evolution of insecticide resistance is discussed.

Section: Discussionmentioning

confidence: 99%

Chromosomal localisation of fitness modifiers of diazinon resistance genotypes of Lucilia cuprina

McKenzie

Purvis

1984

“…Some of these interactions in Tribolium have been well studied, such as the cannibalistic interactions which are known to vary with the age, sex, genotype, and density of both cannibal and victim (Sonleitner, 1961;King and Dawson, 1972;Sokoloff, 1974;. Other interactions, such as male-male reproductive interference (Birch et al, 1951;Osborne, 1968), release of toxic quinones (Park, 1934;1935;1938a;Park and Woollcott, 1937), and larval-larval jostling (Park, 1938b;Mertz and Robertson, 197Q: Kence, 1973;McCauley, 1978), are less well understood but are known to vary between genetic strains.…”

Section: Introductionmentioning

confidence: 99%

“…As a result of those mechanisms of population growth and regulation mentioned above (see King and Dawson, 1972;Mertz, 1972 andSokoloff, 1974 for reviews) population growth rate is a complex function of the density-dependent interactions of individuals in addition to individual traits such as fecundity and development time. Several studies (McCauley, 1978;Wade, 1979;McCauley and Wade, 1980) have shown that large observed differences in population growth rate between strains cannot be predicted from studies of the demographic characteristics of single individuals removed from their ecological context.…”

Section: Introductionmentioning

confidence: 99%

The populational effects of inbreeding in Tribolium

McCauley

Wade

1981

SUMMARYReplicated populations of the flour beetle, Tribolium castaneum, were reared under nine population structures consisting of combinations of three effective population sizes and three interdemic migration rates. For each treatment, the expected loss of genetic variance within demes owing to the cumulative effects of finite population size was calculated and related to observed changes in density-dependent population growth rates. A strong positive correlation was demonstrated between the predicted decline in within-deme genetic variarce and the degree to which a deme's rate of increase declined over time. Notably, changes in the rate of population increase could be detected when the predicted loss in genetic variance was as low as 10 per cent.

“…Kimura, 1971;King and Dawson, 1972), linkage disequilibrium in newly started polymorphic populations might in part be responsible for the outcome of many experiments that at first sight indicate dominance, overdominance or frequency dependent selection at marker loci. It is therefore worth while to describe an experiment which clearly demonstrates the role that linkage disequilibrium may play with respect to the behaviour of marker alleles in a pooled population.…”

Section: Introductionmentioning

confidence: 99%

Linkage disequilibrium causing selection at a neutral locus in pooled Tribolium populations

Stam

1975

SUMMARYThe role of linkage disequilibrium with respect to the changes in allele frequencies at a marker locus in newly started polymorphic populations is demonstrated using the marker locus black in Triboliwn. The experiments, jointly taken, indicate that the black locus is selectively neutral, or nearly so, under the current experimental conditions.A number of possible mechanisms for selection at the neutral marker locus,i.e. a single linked or non-linked locus and a number of linked and/or nonlinked loci through which selection acts, are discussed. On the basis of the experiments some of these models can be excluded, leaving three models for further evaluation: (A) a single linked fitness locus, (B) a number of linked fitness loci and (C) a number of both linked and non-linked fitness loci. The first of these models allows estimation of parameters (recombination fraction and selection coefficients). Models B and C are described in terms of heterozygosity of chromosome pairs. It is argued that in view of the history of a laboratory mutant stock, model C fits best to the experimental results.