Theodosius dobzhansky discovered that successful species tend to have a wide variety of genes that do not appear to be useful to the species in its present environment. what did this discovery explain about genetics and the changes that occur in a species over time?

Which statements explains what the fossil records indicates? check all that apply. a) earth is 4.5 billion years old b) many organisms have become extinct c) mammals have always existed on earth d) mass extinctions have occurred several times on earth e) the amount of water on earth has decreased over time?