At best we could affirm only that a behavior has been historically considered good or evil. What that behavior's moral status will be in the future remains undecided. If we still wish to affirm the premise that murder is eternally wrong, we need a more stable source than nature. The suggestion that murder is wrong because nature said so also generates a practical objection. In nature, life has always been a matter of survival of the fittest, kill or be killed.
Weeds survive by strangling other plants and taking over their food supply.
Bacteria, fungi, viruses, and their comrades follow similar strategies. Were we to learn any lesson from living things, it would be that murder is acceptable, if not recommended, behavior. And inanimate objects and forces are no kinder. Landslides, tidal waves, earthquakes, and lightning bolts murder indiscriminately. If murder is always wrong, it cannot be because nature made it so.