IDENTIFYING A KEY STEP IN THE EVOLUTION OF MEIOSIS FROM MITOSIS. In the evolution of the eukaryotes, it can be assumed that the earliest eukaryotic species were single-cell haploid forms, possessing just a single set of chromosomes, and that they propagated by mitosis.

What was the first eukaryotic cell?

Because eukaryotes are the only organisms on Earth that can make these molecules, scientists concluded that eukaryotes—probably simple, amoeba- like creatures—must have evolved by 2.7 billion years ago. The oldest eukaryotic body fossil is the multicellular alga, Grypania spiralis.

Are eukaryotes haploid or diploid?

Most (but not all) eukaryotic cells contain two sets of their genetic information. Such cells are called diploids. During the process of sexual reproduction, specialized diploid cells undergo a form of nuclear division known as meiosis by which the total informational content is halved.