As shown by the phylogenetic [study of the evolutionary process of new species or organisms] evidence, the earlier organisms that have survived on the planet lacked a developed sexual reproduction mechanism, which would have supported sexual reproduction. This disables them to reproduce sexually and generate gametes required for sexual reproduction.
The asexual mode of reproduction became their only means of reproduction to maintain their species on the planet. The asexual mode of reproduction used by eukaryotes can be similar to that of prokaryotes [bacteria].
Some organisms might have undergone the asexual mode of reproduction. Certain phylogenetic evidence revealed sexual reproduction as a method of reproduction in few eukaryotes in the past. This is based on the evidence involving sexual reproduction processes such as meiosis, a prerequisite for the production of gametes.
Sexual reproduction involves more processes and requires essential genes, thereby making the process more complicated than asexual reproduction. The complex processes, during evolution, tend to become simple and modify to adjust to changing environments. It can be inferred that a less complicated process is derived from a more complicated process. The asexual mode is simpler than the sexual mode of reproduction.
By studying the phylogenetic evidence, it can be inferred that earlier eukaryotes reproduced sexually. Sexual reproduction is a more complicated process than the asexual mode of reproduction. From this information, it is obvious that a less complicated mode of reproduction is derived from a more complicated process.