Because while the population isn't the same, there is too much overlap to consider them completely separate populations. (illinoisdivorcelawyerblog.com)
She says the barrier the desert would have created would have separated populations for at least 500 to 700,000 years. (newsweek.com)
This exchange of larvae by currents between geographically separated populations create a network of connections, which is known as a connectivity network. (sciencedaily.com)