Abstract:
It is important for regulators and managers to effectively distinguish native from
alien taxa. However, a taxon can have both native and alien populations within the
same country as biogeographic and administrative boundaries do not always align.
Here we propose a protocol for classifying populations as native, alien, cryptogenic,
or native-alien, and describe the evidence required. This protocol comprises of
three questions: (1) is the population outside the historic native range of the taxon,
(2) is/was natural dispersal from the native range unlikely, and (3) is the taxon native
to a part of the administrative region where the population is found. If information
on introduction pathways, genetics, and biogeographical barriers is available, we
propose an alternative process to answer question 2. The protocol was applied to
176 suspected native-alien populations in South Africa. A total of 132 populations
from 77 native taxa were classified as native-alien, 13 as cryptogenic, 13 as alien
(native-alien status uncertain), and 18 as native. We believe the protocol provides a
transparent and standardised method for categorising native-alien populations and
thereby facilitates the appropriate regulation and management of this type of
biological invasion.
