A team of scientists from Okinawa, Japan are using little robot rodents to study evolution. Using robots allowed the team to shorten the time period necessary to see evolution in action.
Studying the mechanisms of evolution in live organisms can be difficult due to the fact that evolution takes a lot of time. In fact, it takes millions of years for some species to evolve into a totally different species. In order to shorten the time frame necessary to observe the inner workings of evolution, researchers from the Okinawa Institute of Science and Technology (OIST) have decided to run evolutionary simulations using little rodent-like robots. The team published its findings in the online journal PLOS ONE.
To study evolution, the scientists decided to tackle the evolution of different mating habits. Different animals and organisms each have varying reproductive strategies in order to attract individuals from the opposite sex.
To simulate these complex mechanisms in action, the team used a group of "Cyber Rodent robots" with an infrared port to simulate mating, two wheels for locomotion, electrodes for recharging their batteries and a camera to provide the robots a means of locating batteries for charging.
"We used a survival and reproduction task where the robots maintained their energy levels by capturing energy sources and physically exchanged genotypes for the reproduction of offspring," states the study. "The reproductive success was dependent on the individuals' energy levels, which created a natural trade-off between the time invested in maintaining a high energy level and the time invested in attracting mating partners."
In theory, there should only be one distinct reproductive strategy in a single population. This strategy, which can be considered as a phenotype, exists due to the mechanisms of natural selection choosing the best possible strategy to ensure the survival of a species. In nature however, things are a bit different. Some species exhibit polymorphic mating strategies showing that it is possible for a single population to use multiple reproductive strategies.
"Studying the evolution of such behaviors in living populations of complex animals is exceedingly difficult. By using robots and computer simulation, Dr. Elfwing is able to watch evolution happen over 1,000 generations in a short period of time, something that is impossible to do in live animals," says OIST. "This is why some scientists have turned to robots to study evolution and see if they can understand how different behavioral strategies develop within a population."
The diminutive robotic rodents could only accomplish two tasks, searching for another robot to "mate" or looking for batteries to recharge their energies. This two actions simulate feeding and reproduction in the wild.
"The experiments were run in computer simulation to observe the evolutionary process over 1,000 generations in each experiment," OIST says. "In the situation when both a battery and the tail of another robot are visible, two main phenotypes in mating strategies emerged: first, a Forager that only went for the battery and would never wait for the partner to turn around for mating. It would only mate when it saw the face of a potential mate. Second, a Tracker that would wait for the mating partner to turn around for mating."
In a batch of 70 experiments, the researchers found that some of the experiments indicated that both Tracker and Forager phenotypes were present at the same time. Tweaking the phenotype ratios of the two traits also showed that a stable ratio between Trackers and Foragers occurred at 75 percent and 25 percent respectively.
The OIST scientists observed that the results of their experiments mirrored that of polymorphic mating behavior seen in the wild. Moreover, the team also noted that the experiments where both mating behaviors were present also showed the highest rates of reproduction and the "fittest" robots. This shows that multiple mating strategies existing in specific ratios offers the best chance for the survival of a species.
