Meaning of selection pressure

I am confused as to what a selection pressure actually is? Is it just some factor in the environment e.g. temp that drives evolution?

Reply 1

JessNaomi19600

14

According to my exam board (eduqas), a selection pressure (or a selection agent) is an environmental factor that can alter the frequency of alleles in a population. For example, temperature (the selection pressure) effects the survival of mosquitos. Mosquitos that can survive in a habitat with a high temperature will have an advantage over mosquitos which cannot survive at that temperature. Therefore, those mosquitos will survive and breed, resulting in more of their offspring having the advantageous alleles, resulting in more advantageous alleles in the gene pool of the population. There are many different selection pressures which effect the frequency of alleles in a population, such as overcrowding, disease, predation and many human impacts.

Hope this helps :smile:

Original post by Bertybassett

I am confused as to what a selection pressure actually is? Is it just some factor in the environment e.g. temp that drives evolution?

Reply 2

Bertybassett

OP

11

Original post by JessNaomi19600

According to my exam board (eduqas), a selection pressure (or a selection agent) is an environmental factor that can alter the frequency of alleles in a population. For example, temperature (the selection pressure) effects the survival of mosquitos. Mosquitos that can survive in a habitat with a high temperature will have an advantage over mosquitos which cannot survive at that temperature. Therefore, those mosquitos will survive and breed, resulting in more of their offspring having the advantageous alleles, resulting in more advantageous alleles in the gene pool of the population. There are many different selection pressures which effect the frequency of alleles in a population, such as overcrowding, disease, predation and many human impacts.

Hope this helps :smile:

Sorry didn't realise that I hadn't thanked you. This was really helpful

Reply 3

anosmianAcrimony

20

One of the most important selection pressures to understand nowadays is the selection pressure that antibiotic use puts on bacteria. Bacteria that can survive a given antibiotic are selected for, so bacteria get more and more resistant over time.

Bacteria don't generally become completely immune to a given antibiotic, so using enough antibiotic to kill off SOME of an infection but not ALL of it is particularly bad. That's why pharmacists tend to prefer that you finish your prescription even if you feel fine.