These results suggest that high environmental temperature could select for more virulent bacteria in environmental reservoirs, while selection by phages could constrain this effect.
Type IVB pili may contribute to attachment and motility, and pyocin expression could select for small colony morphotypes as does for example the selection pressure imposed by exposure to antibiotics or bacteriophage [43].
An environment that has worms in some parts but mousetraps in others could select for a mixture of go-getters and nervous nellies.
Because parents could select for sex before birth, they were less likely to select for sex after birth – that is, less likely to kill their unwanted girl children, either by neglecting them or simply murdering them.
Antimicrobial usage in animal farming could select for antimicrobial-resistant bacteria that may spread to humans either through direct contact, consumption of meat or indirectly through environmental pathways (Marshall and Levy 2011).
The latter could select for bacteria that reduce ({text{NO}}_{3}^) to ({text{NO}}_{2}^) over denitrifiers, so ({text{NO}}_{2}^) accumulation would be due to microbial selection, not the intrinsic kinetics of a denitrifying system.
Over the long term, both kinds of modified mosquito could lose their edge, because evolutionary pressure could select for resistance to either Oxitec's lethal gene or Wolbachia's virus-fighting powers.
However, theoretical studies have raised the concern that "imperfect vaccines," vaccines that do not induce sterilizing immunity but rather modulate disease or transmission, could select for increasing virulence in the wild-type virus targeted by vaccination (Gandon et al. 2003; Mackinnon et al. 2008; Gandon and Day 2007; Andre and Gandon 2006; Ganusov and Antia 2006; Massad et al. 2006).
If the tactic doesn't completely eradicate dengue -- Wolbachia-infecrted mosquitoes can still be slightly susceptible -- it could select for resistant mosquitoes and more aggressive viruses, warned Hanley.
Thus, antagonistic interactions between bacteria and either their phage or their protozoan predators could select for less pathogenic bacteria through trade-offs between defensive and virulence traits.
A bird could select for those with genetic resistance to a pathogen by avoidance of potential mates that are infected [66].
