Variation in a trait is a required condition for natural selection to act on a population for that trait. Assuming a population of organisms only started with only one form of a trait, what are two ways variation in the trait could be introduced into the population?

I) Sexual reproduction

II) Mutation

Explanation:

Variations refer to the difference observed within organisms of the same species. Variation are introduced into a population by:

- new genetic combinations that occur during sexual reproduction (i.e during meiosis)

- mutations, spontaneous changes that occur in genes and chromosomes.

i think it would be b. tissue because an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.

phylogenetic tree is the tree of life or evolution tree. it shows the different branches of evolution. the sequence goes like tissues - coelom - backbone - endoskeleton - segmentation