A few years after your initial study of Salamander X, you observe them breeding with another population of salamanders. The breeding results in offspring. You want to determine if Salamander X and the other Salamander are the same species. According to the Biological Species Concept, what must be true in order for the salamanders to be considered the same species? the offspring must be fertile
the offspring must be infertile
reproductive isolation must have occurred
we cannot determine if they are the same species