system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If the first living beings reproduced asexually, how did diverse species came to be? Also how did sexual reproduction started?

I understand that the first living beings were unicellular organisms, prokaryotes, which reproduce asexually. If DNA was only "cloned" from one organism to form an offsrping, how did different species appeared? I'm guessing it has to do with some kind of genetic mutation, but even then I can't wrap my mind around how sexual reproduction started.
gpt
Well it helps to look at species that have various forms of reproduction between asexual and our form of sexual reproduction. 

For instance prokaryotes can't go through meiosis but can incorporate new DNA from other prokaryotes. 

Then there are some yeast cells that can reproduce asexually or sexually when under great stress. 

Then there are various hemaphrodites in the animal kingdom. 

Then there are species that can change sexes like clownfish. 

Then there are true sexually dimorphic species like us. 

Do you have a more specific question. 

Edit: Also it helps to think that sexual reproduction (meiosis) is really just a modified version of asexual reproduction (mitosis) done twice. Then you just have specialization of specific parts and genders overtime.