Carriers of the sickle-cell allele (i. e. those with a heterozygous genotype) are fittest in environments with high frequencies of:

Individuals who are heterozygous for the sickle-cell allele suffer less from the attack of malaria because a small percentage of the red blood cells are sickle-shaped. They are more resistant to malaria than individuals who have two copies of the normal haemoglobin allele. Heterozygous individuals have a better chance of surviving and reproducing in regions where malaria is prevalent since they do not fully contract the disease.

No because the eaeht is on a 23.5 degree axis tilt and so when it is winter the northern hemisphere is pointing away from the sun and the soutubern hemisphere is pointing toward the sun

Birth orgraduate orschool