lecture 12

• Populations are large and have a lot of variation so some are more resistance than others • New mutations will be favored • Gene flow: Resistance alleles exist somewhere else and if it comes into the population, it will spread by selection

• first the population will decrease and about to go extinct • the strong selection is going to favor the individuals with the trait that helps them survive • the survivors reproduce and pass their traits allowing the population to grow again

• multi herbicide treatment - Harder for a plant to adapt to 2 treatments • rotating between different herbicide - Once they have resistance to one kind of pesticide, we will switch it up

• We can use one type of insecticide till it stops working then switch it • We change the insecticide when it stops working

• We switch up the chemicals • In periodic application we do it periodically (set time) and in responsive alternation, its not periodically

• In one patch, we apply 1 pesticide and another patch, we apply another pesticide • Reduces global adaptation

• Uses 2 chemicals at once • Slows down evolution • Eventually, they will evolve resistance

• Once resistance evolves, the patient stops taking drugs • The virus with the resistance will decrease and the ones without resistance will increase • When we re apply the drug, it can work effectively

• When we use a strong dose, the selection is stronger • when we use a strong dose, it kills a lot of the population and only a few survive, they have resistance • the resistant ones survive so future population will have strong resistance • When we use a less aggressive treatment, there was less evolution of resistance • some non resistance ones will survive too • resistance will evolve more slowly