While negative size-selective mortality then selects against small individuals, positive size-selective mortality selects against large individuals, potentially shifting the populations mean weight towards the middle.
Natural selection arising from these interactions selects against intermediate phenotypes, included hybrids, and thus has contributed to the origin and persistence of stickleback species.
G402 was transformed with a LEU2 plasmid expressing either SSA1, 2, 3 or 4. Transformation plates were replica plated onto selective medium containing 5-fluoroorotic acid (5-FOA), a chemical that selects against URA3 cells and hence against the presence of the pRDW10 plasmid.
In addition, the DNA to be transformed was size-selected prior to transformation using a preparative agarose gel, a technique which also selects against circular plasmid forms.
You can take a path of choices to form something like an entire treatment that selects against resistance".
Therefore, broiler litter selects against this bacterium, and broiler litter is an unlikely environmental source of this bacterium.
For example, the diphtheria toxoid vaccine selects against toxin production, which is what causes disease, rather than against growth or survival of the Corynebacterium.
Any environmental change that selects against the clone would have to operate on this time scale or shorter, or the clone would win.
It is hypothesised that there is a cost to dispersing to a new site, the chance of not finding a mate of the same species, that selects against it for rarer species, whereas there is probably an advantage to dispersal for species that have colony sites that change dramatically during periods of glacial advance or retreat.
We used the 5-fluoroorotic acid (FOA) that selects against strains that contain the URA3 gene.
This is not because of drift, but because the frequency-dependent mechanism of conformist cultural transmission actively selects against all non-modal variants.
