In science class you learn that there are different types of reproduction. Some organisms can reproduce sexually making genetically diverse offspring while others reproduce asexually creating genetic clones of the parent. You began to wonder if there were any organisms that could reproduce using both sexual and asexual reproduction. Through some research you find that there are some sharks that can. These sharks use a process called facultative parthenogenesis to reproduce asexually when needed. Since there are many advantages to reproducing sexually, these sharks typically only reproduce asexually when finding a mate is difficult. For example, female Zebra sharks will reproduce asexually if they are unable to find a mate in their ocean habitat or have been documented to reproduce asexually if they are in captivity without male sharks. Parthenogenesis was thought to be rare in vertebrates, but has been discovered in more species recently. Today the largest species documented reproducing through the use of parthenogenesis is the Komodo Dragon at 10 feet long and weighing over 300 pounds!
One of the differences between asexual and sexual reproduction you learn in class is their reproduction rate. You learn that organisms that reproduce asexually typically have faster reproduction rates that produce more offspring, while organisms that use sexual reproduction have slower reproduction rates producing fewer offspring. Additionally, you learn that organisms that reproduce sexually are much more successful at adapting to environmental changes due to their genetic diversity. You begin to wonder just how much environmental factors would impact the reproduction rate of an organism that reproduces asexually. You decide to set up a controlled experiment to find out. You find some Planaria in the stream near your home. Planaria are one of many flat worms that can be found in aquatic environments. Planaria are used frequently in studies due to their unusual ability to regenerate or regrow lost body parts. Planaria flatworms reproduce by taking advantage of their regeneration capabilities, which you know is a type of asexual reproduction called fission. When conditions are favorable, the organism will attach it's tail end to the ground and pull forward with it's head end until it tears itself in half. Each end will then regenerate the missing half. The two "new" Planaria are clones of each other, both possessing identical genes. Further research shows that environmental factors can impact stream quality. These factors include the amount of dirt in the water, amount of dissolved oxygen and nitrogen as well as the presence of chemicals like fertilizers.
Based on the scenario and background information, which of the following would be the best option for the testable problem statement for your experiment?
What is the effect of types of reproduction on the environment?
What is the effect of rate of reproduction on types of reproduction?
What is the effect of reproduction rate on environmental factors?
What is the effect of environmental conditions on an organisms reproduction rate