Both Karl and Jose are likely to get sick this time since Jose's vaccine was dead, but neither will get it again once they acquire active immunity.
Karl will get sick and Jose will not this time, but neither will get this influenza again since they both will have acquired active immunity to it.
Karl will get sick and Jose will not this time, but Jose will be more likely to get it later since his immunity will be less recent than Karl's.
Both Karl and Jose will get sick this time since Jose's immunity has had time to wear off, but Karl is more likely to get it again since he has only been exposed once.
<u>Changes in inheritable physical or behavioural traits</u> due to changes caused by variations as the organism move from one generation to another.
In addition changes in selective pressures of their new environments in order to gain adaptions for survival in the new environment is another factor for this changes.
