Why is sexual reproduction and meiosis advantageous

One of the most important advantages of sexual reproduction is that it results in genetic variation among offsprings. This is a result of meiosis, which is the halving of the number of chromosomes and fertilization, whereby the male and female sex cells fuse and the restoration of the original number of chromosomes.Advantages of Meiosis 

Tremendous storehouse of genetic variation provides for adaptations to changing environment 
Asexual organisms depend primarily on mutations to generate variation 
 Meiosis produces genetic variation. Hope that helped