Genetic variation and the ability to colonise new niches in the flour beetle Tribolium castaneum (Herbst) (Coleoptera, Tenebrionidae)

Abstract

A genetically-heterogeneous synthetic strain of the flour beetle, Tribolium castaneum (Tenebrionidae) survived better than the laboratory strains used in its synthesis on 10 of 12 different diets. This advantage was not expressed in the optimal, standard wheat flour diet. Moreover, the synthetic strain survived on 12 diets, while most of the laboratory strains survived on 8 or less.The food medium is an entire ecological habitat for flour beetles. The results thus illustrate the better colonising ability and superior potential for evolutionary success of genetically-heterogeneous populations.

Attraction of flour beetles, Tribolium castaneum (Herbst) (Col., Tenebrionidae) to wheat flour: heritable character or “conditioning”?

“…The lack of change in behavior in our study of flour beetles during 13-16 experimental generations, when changes in survival were observed (BERGER-SON 1985;BERGERSON and WOOL 1987), shows that, at least for this organism and for the experimental system used, mutations leading to changes in host selection are not frequent, and/or that selection for them is ineffective.…”

“…This explanation does not seem to apply to our Tribolium because the beetles showed no tendency to prefer the medium on which they were selected. The procedure of selection did not eliminate all contact with the standard medium (BERGERSON and WOOL 1987): Oviposition every generation was in the standard medium. However, only the eggs were used to start the new generation, and the emer ing adults had never experienced any medium but the selective one.…”

“…The experimental diets were taken from a list of 15, prepared for another study (BERGERSON and WOOL 1987). In the 4-diet test cages we used the standard medium (wheat flour supplemented by 5 % Brewer's yeast), wheat germ (semolina), powdered rice, and cornflour.…”

“…The synthetic strain was tested 5 times in the cages. In each test the standard medium was provided with three other diets, which were not the same in different tests (including 7 which were not listed above; see BERGERSON and WOOL 1987). Invariably the majority of the beetles were found in vials with the standard medium, and yeast was the least attractive (data not shown).…”

Relative Contribution of Inbreeding Depression and Eroded Adaptive Diversity to Extinction Risk in Small Populations of Shore Campion

“…This diversity is of course important for evolution in the long term, but given that evolution often occurs on contemporary timescales (reviewed in Reznick & Ghalambor 2001 and Stockwell et al 2003), it may also be critical in the short term (Conner 2001). For example, if genotypes in a population were differentially adapted to different microhabitats, the population could maintain higher numbers in heterogeneous environments (as observed by Ellstrand & Antonovics 1985), persist in the face of biotic or abiotic environmental changes (Den Boer et al 1993; Schemske et al 1994), or have an increased colonizing ability (Martins & Jain 1979; Bergerson & Wool 1986). Similarly, diversity in alleles associated with disease resistance may enable populations to resist pathogens (O'Brien & Evermann 1988; Fiedler & Kareiva 1998; Hughes & Boomsma 2004).…”