Explain the term selective pressure as it relates to changes in populations

Selection pressures are external agents which affect an organism's ability to survive in a given environment. Selection pressures can be negative (decreases the occurrence of a trait) or positive (increases the proportion of a trait)

Selection pressure are external agents which affect an organism ability to survive in a given environment, selection pressures can be negative ( decreases to occurrence of a trait) or positive ( increases the proportion of a trait)

a "theory" a suggestion that is not 100 % accurate, or a figure. some people say its a theory because they of all the passed theory's about one subject. it depends sometimes theory might be accurate and sometimes they are.

climate change and pollution