Tomoko Ohta was a very smart lady who studied animals and how they evolved. She wanted to understand how different animals came to be and why they were different from one another.
She discovered something called genetic drift, which means that sometimes genes (which are like instructions that tell animals what to look like and how to behave) can change randomly in a group of animals. This can happen over time if that group gets separated from other groups or if there are only a few animals in that group.
Ohta found out that genetic drift could actually have a big impact on how certain animals survive and evolve over time. For example, if a group of animals with a certain gene all die off because of a natural disaster, then that gene will be lost forever unless it exists in some other groups too. On the other hand, if a certain gene becomes really common in a group of animals, then it might lead that group to evolve in a certain way that is different from other groups of the same animal.
Overall, Tomoko Ohta helped to explain how random changes in genes can affect the evolution of different animal species. Her research has helped scientists better understand the ways in which animals adapt and change over time.