When humans started industrialization we cleared land that once was habitats for other animals and global warming started when we started using all of those fossil fuels cause all that gas don't go nowhere and if a volcano erupt the lava can cover the whole island which will start the ecological succession or a thunder storm when lightning hit the ground it can cause a forest fire.
Answer:
Because natural selection selects for it. Thus it persists.
Explanation:
You have to understand heterozygote advantage. Basically, it's where heterozygotes have an advantage over homozygotes. In the case of sickle cell disease, heterozygotes have an advantage, and natural selection favors whatever is advantageous. Thus, because heterozygotes each have one recessive sickle-cell allele, as natural selection favors the heterozygotes, the recessive sickle-cell allele persists and remains in the gene pool.
The answer is A. Excretion I hope this helps
<em>it would be b and c</em>
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<em>it's the whole ''ecosystem''</em>
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