Answer:
The earth surface is getting hotter because of global warming
Explanation:
In ecology<span>, a </span>niche<span> (</span>CanE<span>, </span><span><span>UK:</span> <span>/<span>ˈniːʃ</span>/</span></span><span> or </span><span><span>US:</span> <span>/<span>ˈnɪtʃ</span>/</span></span>)[1] is the fit of a species living under specific environmental conditions.
<span>https://en.wikipedia.org/wiki/Ecological_niche</span>
Because bacteria mutates that's why we have a new flu vaccine every year , because strains of DNA in the bacteria change all the time.
